Travel and health [full issue]

WORLD HEALTH THE MAGAZINE OF THE WORLD HEALTH ORGANIZATION • APRIL 1982 TRAVEL AN D HEALTH \-1 !Him, IN III tr, ld!!!!!!!!!!!!!!!" 11 *! ‘' * .41411:*'1311, 4111,11614L I ...""ir • tt tigilorty ' *, . , .. t qi HI 'I' IN '1`111,11 11111111'H Ill 1141'11 L • :A • 1,4,s! Cover: Photo-montage designed by P. Davies; photos L. Sirman ©. y -- xs IX ISSN 0043-8502 World Health is the official illustrated magazine of the World Health Organization. Editor: John Bland Deputy Editor: Christiane Viedma Art Editor: Peter Davies News Page Editor: Peter Ozorio World Health appears ten times a year in English, French, Portuguese, Russian and Spanish, and four times a year in Arabic and Persian. Articles and photographs not copyrighted may be reproduced provided credit is given to the World Health Organization. Signed articles do not necessarily reflect WHO's views. World Health, WHO, Av. Appia, 1211 Geneva 27, Switzerland. Contents Travel and health by James Haworth 3 Malaria — "King of Diseases" J. H.-G. Hempel 6 Keeping insects at bay by Alec Smith 11 Travellers' diarrhoea by R.H. Herniman 15 Viral hepatitis by Arie J. Zuckerman 19 Is it safe to eat? by John Bland 22 Viruses transmitted by insects by P. Bres 25 The siren-song of seduction by A. Siboulet 28 News Page 30 e can think of international travel as a four-sided arrange- ment between the traveller, the travel organization, the transport company and the host government. Some host governments go to enor- mous pains to protect their guests. Saudi Arabia, for example, spends hundreds of millions of dollars on medical and health services during the hajj—the annual pilgrimage of devout Moslems to Mecca. Recently, at a cost of several million dollars it purchased 60 special beds to allow cool air to be blown all over the bodies of heat-stroke patients. Many other countries are rigorous in their inspection of hotel hygiene, particularly food hygiene ' in the kitchens. Others, regrettably, fail in their responsibilities—a failure which casts a grave reflection on the govern- ments responsible. It is understandable that some governments may be reluc- tant to disclose their health problems since they feel that these may discour- age tourists; but, in the long run, tourists who become ill because of undisclosed diseases in a country are the worst possible advertisement for that country. Tourists are seldom deterred from visiting an area where By sea and by air, millions of travellers every year are on the move around the globe. They include migrant workers in search of jobs, pilgrims of many sects, businessmen, family visitors and tour- ists. And millions more travel by train, coach and car. ( Photo L. Sirman ()) there is a health risk, provided that risk is made known and the precautions to avoid it are understood. But the traveller too—whether he or she travels on business, on holiday or for family reasons—has responsibili- ties. Travellers should ensure that all precautions are taken against any preventable disease by immunization, drugs and careful behaviour. If they fall ill on their return, they should advise their medical prac- titioner where they have been. Unfor- tunately doctors in many countries are frequently ignorant of health hazards elsewhere. From time to time there are reports in the newspapers about return- ing tourists dying of malaria because the disease has not been diagnosed when they reached home. This is not altogether surprising, since of the three million physicians in the world prob- ably fewer than a quarter have ever seen a case of malaria. Appalling examples occur of travellers who have been bitten by rabid dogs but who are advised neither by local doctors in the country they are visiting nor by their doctor back home to have antirabies vaccine; the result is an agonizing death. People often visit some region of their own country and contract an illness caused by something they have eaten and drunk, because they have given no thought to such possible dangers; yet they will visit some country which is notorious for its low health status without suffering, be- cause they have been warned of the dangers and have taken the necessary precautions. Travel and health Each year, millions of people climb aboard air- liners, ships, buses or cars and travel beyond the frontiers of their home country. What are the health consequences of this mass travel? by James Haworth The travel organization should be able to tell the traveller in detail about the health conditions in the countries to be visited. A useful book is published by wHo to help health administrations to advise those concerned, and is of particular value for travel organiza- tions. This is Vaccination Certificate Requirements for International Travel and Health Advice to Travellers, 1982 (obtainable from Distribution and Sales, World Health Organization, 1211 Geneva 27, Switzerland. Price: 12 Swiss francs). It lists some health risks to which travellers may be subject in different parts of the world, and suggests the precautions that they can take against certain diseases and injuries. Transport companies have two dis- tinct responsibilities. Firstly, to advise travellers if a particular health risk exists in the country of disembarkment, especially malaria—some airlines even supply the traveller with a small pack of an anti-malaria drug. Secondly, they must ensure that their own food hygiene is impeccable. Codes of recom- mended practices and recommenda- tions on the application of specific procedures for monitoring sanitary food and water standards have been established by such bodies as the International Air Transport Associa- tion (IATA) and the International Civil Aviation Organization (IcAo). These are available to their members' airlines and to related multinational hotel groups. Similar standards should be maintained on passenger liners and in all establishments used by land trans- port operators. ( \NTH° has also publish- ed the following: Guide to Hygiene and Sanitation in Aviation, by J. Bailey; Guide to Ship Sanitation, by V. B. Lamoureux, and Guide to Sanitation in Tourist Establishments, by J. A. Salvato, Jr.) WHO has a collaborative role in this four-sided arrangement through its liaison with IATA, ICAO and the Inter- governmental Maritime Consultative Organization (imco), as well as with the World Tourism Organization. In addi- tion, it is a sounding box on international health, receiving in- formation from member countries and disseminating it in a journal called the Weekly Epidemiological Record. It also advises governments on precautions to be adopted when disease outbreaks occur, and draws their attention to health regulations when they are too stringent or are in excess of the requirements of the International Health Regulations. Food and water sanitation has been touched on above, and the subject will recur in several of the articles that follow. Failure on the part of govern- ments, local authorities and caterers to maintain adequate sanitation can mar a holiday or a business trip completely. One effect of inadequate food and water hygiene, as well as of carelessness by the traveller, is diarrhoeal disease. Travellers' diarrhoea is extremely com- mon and takes many forms, but all are caused by an infection. As another of our articles shows, drugs play little part in curing this condition, but in high- risk areas certain prophylactic anti- biotics may be of value for short visits, particularly for people who are not in full health. The most dangerous and debilitating effect of diarrhoea is de- hydration. This can be overcome by drinking dissolved oral rehydration salts, which are readily available in most countries. Insect pests and insect -borne diseases are fully dealt with in three separate articles—on the insects and methods of protection, on the virus diseases transmitted by insects, and on ma- laria. Apart from carrying disease, 4 Travel and health Left: Loaded with calabashes and per- sonal belongings, this truck in a West African country carries vill- agers moving to the big city in search of work and better living conditions. Inadvertently, it could also carry "hitch-hikers" — in the form of various potential agents of disease. Right: Pictured at a caravan camp in Western Europe, these tourists take it for granted that the water supply is fit for washing, brushing teeth and even drinking. But they might be wrong! (Photos WHO/P. Pittet and WHOIPublifoto) insects have a great nuisance value, particularly for people who react in a hypersensitive manner to such bites and may become quite ill as a result. Biting insects occur all over the world; in some areas of the far northern tundra, blackflies may cause severe loss of blood in unprepared travellers. But vector-borne diseases are mostly prevalent in the tropical zone. The risks are quite different in urban and rural areas. In the towns, malaria, dengue, sandfly fever and possibly yellow fever may occur, but in the countryside all these are more likely and there is the additional risk of sleeping sickness (in parts of Africa), Chagas' disease (in Middle and South America), filariasis (including river blindness), plague and various virus diseases. Of the virus diseases, only yellow fever and equine and tick-borne encephalitis can be prevented by immunization. Further articles in this issue deal with dengue and dengue-related diseases, and also with the one virus disease that is found all over the world—viral hepatitis (though this is not normally insect- borne). Another contributor deals with malaria, that bane of residents and travellers alike wherever there are the appropriate species of mosquitos in the tropics and subtropics. It is easily prevented by prophylactic drugs, if these are taken regularly and continued for at least a month after leaving a malarious area. The main danger for tourists is that the disease may not be recognised by physicians back in their home countries who have not previous- ly encountered it. Sexually transmitted diseases: There is no doubt that travellers of all categories run a higher risk of con- tracting venereal disease through ca- sual sexual contracts. In many cities, professional prostitutes, whether male or female, have regular medical check- ups for their own good; the greater risk comes from "non-commercial" en- counters. Pious exhortations to refrain from sex altogether during long periods away from home are not likely to change human nature. So the best ways of cutting down the risk of infection are for the man to use a sheath, and for both partners to be very careful about their hygiene. Mass movements of people, such as occur in pilgrimages, lend themselves to the transmission of infectious di- seases if proper precautions are not taken by the authorities. New diseases can spread rapidly among the non- immune pilgrims; especially where there is crowded sleeping accommoda- tion, diarrhoeal diseases may be rampant unless hygiene is carefully supervised, and food poisoning is common. The medical staff available are often overwhelmed by the volume of work. Pilgrimages require exceptionally detailed planning and staff manage- ment on the part of the health authorities. As mentioned earlier, the government of Saudi Arabia—after many centuries of experience—has solved most of the problems. If the medical teams which usually accom- pany the groups of hajj pilgrims from their country of origin plan ahead in close cooperation with the Saudi Ara- bian Health Administration, remark- ably few adverse health conditions arise as a result of the pilgrimage. As the Weekly Epidemiological Record stated on 30 October last year, "The principal pilgrimage period has drawn to a close and no significant communic- able disease situation has arisen. It is striking that straightforward simple effective surveillance has been the basis of bringing this about." ■ 5 Malaria "King of Diseases" Plasmodium falciparum, the most malignant type of malaria, is a major cause of mortality in infants in countries where it occurs naturally, and weakens the whole population. People who travel to such countries should take every precaution by J. H.-G. Hempel etween 1973 and 1977, there were 40 deaths due to malaria in the Federal Republic of Germany, and 30 of them involved tourists. In 1978, in the United Kingdom, there were nine deaths due to malaria contracted in Africa. In the same year, five Austrian tourists, returning from a safari tour in East Africa, died after being treated for influenza, since nobody gave any thought to the possibility of malaria. These examples underline the risk to unprepared travellers who con- tract falciparum malaria, the most malignant type of the disease. In areas where falciparum mala- ria occurs naturally in the absence of treatment this disease is a major cause of mortality in infants and at the same time weakens the whole population. During falciparum malaria epi- demics, large numbers of people may die from the disease. For example, an outbreak in Mauritius in 1867 caused 6,000 deaths in a single month in Port Louis, which had a total population of 47,000. In the Punjab in October and Novem- ber 1898, more than 307,000 deaths were recorded, as compared with a normal average of 50,000 per month. In 1968, more than three million cases of malaria, with 150,000 deaths, occurred during an epidemic in Ethiopia. Over the centuries, malaria has profoundly influenced human so- cieties throughout the world. In India many centuries before the present era, it was called "King of Diseases", and was also known in ancient China. Whether, as some historians assert, it was decisive in the downfall of Greece and Rome and caused the mysterious depo- pulations that left massive ruins at The fever of malaria as imagined by the English cartoonist Thomas Row- landson about 180 years ago. Facing page: Anti-mosquito spray- ing operations in the shadow of an ancient fortress in the Middle East. (Photos WHO and WHO/ P. Almasy) Polonnaruwa, Sri Lanka, and at Angkor-Wat, Democratic Kam- puchea, cannot be determined; but it is certain that malaria has been one of the great scourges of humanity. Malaria has been so called only since the 18th century. When people died of the intermittent fever in Italy, they were said to be victims of "bad air" or "mal'aria". From about 1900, the word malaria ass- umed its present usage in English. Throughout the ages, suspicion fell on the part played by insects, and the mosquito was incriminated in folklore in Africa, Asia and Europe. But the truth had to wait for the second half of the 19th century, when scientists from many countries contributed to our know- ledge of the complex life cycle in mosquito and man of the various malaria parasites. The main credit must go to Alphonse Laveran, Camillo Golgi and Ronald Ross. The human malaria parasite (or Plasmodium) develops alternately in two hosts, the female anopheline mosquito and man. When a mos- quito bites a person infected with malaria, it sucks up blood which contains the parasites. These par- asites develop in the mosquito and after a short time they infect its salivary glands. When it next feeds, the mosquito injects these parasites into the human body together with the saliva. Once the human being is infected, it takes the parasites from one to four weeks (and occasionally much longer) to appear in the blood and to produce the symptoms of the disease, the acute attacks of which are marked by chills, fever and profuse sweating. Once the mosquito was identified as the carrier of malaria, interest 6 oo.-* too 1.. 4o to- 4r -154k, ageuair-r- NdoolLtdihts7- ,017.,4416%is • tl 164z; r t, ohs- 2 • 4 • .10 1*- 1g1 1fe;" Sr • A oak odo 410 • . ' WV' • fry; NM. ' • P.' (.■ *A.A. • itokifito lob* 4 • revived in the use of mosquito nets (an ancient invention) and in the destruction of mosquito breeding places. By the start of the present century, there was already serious talk of "stamping out" malaria. To the classical method of drainage was added the treatment of stagnant water surfaces with petroleum products in order to destroy mos- quito larvae. Biological control was also attempted by introducing larva-eating fish into ponds and marshes. Methods were devised to kill the adult mosquito and this is now the most widely practised method of controlling malaria. The DDT era DDT was synthesized by an Aus- trian, Othmar Zeidler, as long ago as 1874, but remained obscure until 1939, when Paul Muller, in Switzer- land, discovered that it was an amazingly effective insecticide, an observation for which he received a Nobel Prize. The special impor- tance of DDT is that it has a residual killing effect on many insects which lasts for months when it is sprayed on surfaces where they later walk or rest. Among the first to fully appre- ciate the possibilities of DDT for attacking malaria in rural areas was Dr Arnoldo Gabaldon in Venezuela. In 1945, a national project was launched there to eradi- cate malaria from the entire country using DDT residual spraying. During the 1950s, a number of countries organized programmes to wipe out malaria and some other vector- borne diseases. Above: Jungle growth envelops a giant statue at Angkor Wat, in Democratic Kampuchea. Was it malaria that depopulated that region many centuries ago? Below: A drop of bloodfrom the little girl's finger will be tested for signs of the malaria parasite—part of a routine check among school children in Comoros. ( Photos L. Sirman r and WHO 11 Hudleston) Drugs used for individual protection against malaria Drug or combination Dosage for 60-kg adult Frequency of administration Remarks Chloroquine 300 mg (base) Weekly Tablet bitter: overdose can be dangerous. Some side-effects reported. Amodiaquine 300-400 mg (base) Weekly As for chloroquine Sulfadoxine 500 mg Weekly For use in areas of resistance of & pyrimethamine 25 mg falciparum malaria to 4-aminoquinolines. Not recommended for prolonged use or for pregnant women. (A pregnant woman who is obliged to visit malarious areas where P. falciparum is resistant to 4-aminoquinolines should seek specialist medical advice about the most appropriate form of prophylaxis for her.) from Vaccination Certificate Requirements for International Travel and Health Advice to Travellers (WHO), 1982. rtr alaria can be suppressed by the use of drugs. Before setting out, the traveller should consult his or her doctor, who will advise on the appropriate prophylactic drug and its dosage according to the area to be visited and any drug intolerance the traveller may have. The drug of choice is not always available in the malarious countries visited, and the traveller should be prescribed a sufficient quantity to cover the period of the visit to malarious areas, and a further 4-6 weeks after leaving those areas. Drug prophylaxis should begin at the latest on the day of arrival in the malarious area. The drug must be taken with unfailing regularity to be fully effective; even one single omis- sion of the weekly dose interrupts the protective effect. The drug protection should be continued for at least 4 or, better, for 6 weeks after leaving the malarious area to ensure that infection with falciparum malaria is eliminated, but the other forms of malaria may break through even after that period. This single precaution, if properly taken, would undoubtedly prevent the vast majority of cases of the dangerous falciparum malaria. The possibility of the occurrence of late illness emphasizes the point previously made, namely, that physi- cians should always be alert to the possibility that their patients may have travelled recently and that the traveller should always advise the doctor of such travel. The table above lists some drugs normally used for the chemoprophy- laxis of malaria, the doses calculated for an adult weighing 60 kg. For children the doses should be scaled down in accordance with a physi- cian's advice, and for adults heavier than 60-70 kg the doses may need to be increased. Resistance of Plasmodium falci- parum to 4-aminoquinolines (chloro- quine and amodiaquine) occurs in parts of Middle and South America and South-east Asia. It has also been reported from eastern Africa. In these areas the combination of sulfadoxine with pyrimethamine is indicated as the protective drug; chloroquine or amodiaquine remains the drug of choice for malaria prophylaxis in areas without chloroquine resistance. In India the number of malaria cases had been estimated in 1935 at 100 million annually, with one million deaths. Once the use of DDT started, notifications of malaria dropped sharply, until by 1965 there were only 100,000 cases, with no deaths reported. Similar success was achieved in Sri Lanka, where a nationwide campaign started in 1946-47, and the number of malaria cases fell from 2.8 million in 1946 to 11,000 in 1955 (and to 17 by 1965). These encouraging results led, in 1955, to the adoption by WHO's Eighth World Health Assembly of the concept of time-limited malaria eradication programmes on a world wide basis, with the exception of sub-Saharan Africa. From the be- ginning these programmes were highly successful. But it was soon realised that, although technical problems existed, the main obst- acles to outright success were of an operational and administrative nature. Formerly, about seven out of every ten people in the world were exposed to malaria risk. Today, nearly three out of those seven people living originally under that risk are largely freed from it. In geographical terms, malaria has been eliminated from the whole of Europe, almost all of the USSR, from several countries of the Near- East, the USA and most of the Caribbean, large areas of the north- ern and southern parts of South America, Australia, and large parts of China. Cases of the disease have been imported into malaria-free areas for centuries, but until the advent of air 9 travel most of them, at least from tropical Africa and eastern Asia, developed fever at sea and were treated by the ship's surgeon who was well acquainted with the com- mon diseases that might occur. Today however, the airline routes enable people to move vast dis- tances within the limit of any incubation period, no matter how short. It is useful to remember that the number of air passengers reached 700 million in 1978. In the USA, the number of civilian mala- ria cases imported increased from 143 in 1967 to 585 in 1978. There were nearly 4,400 imported malaria cases in 1978 in Europe against 840 in 1967. Four parasites Among the four malaria parasites that can be transmitted to man, Plasmodium falciparum is the most dangerous, firstly because it is a rapid killer, and secondly because in certain regions it is increasingly showing resistance to chloroquine, the drug currently used for prevention and treatment. In non-malarious countries, hospital pharmacies may not even stock anti-malarial drugs. The diagnosis of malaria is easy—provided the doctor thinks of it as a possibility. A doctor who deals with large numbers of people who suffer only from diseases of temperate climates finds it very hard to remain alert to the possibility of an exotic infection. The clinical signs of a first infection of malaria are often not those that are gener- ally described as typical. In a malaria-free country, many physi- cians will diagnose feverish gastro- enteritis, influenza, pneumonia, hepatitis or nephritis, before they think of malaria. Malaria can mimic all these diseases; the patient—if still conscious often forgets to mention a stay or only a stopover in a malarious area (some airports are mosquito-infested). So it is essential for doctors to inquire into recent international travel when a case history is taken. The tragedy of deaths from falciparum malaria is that this infection is one of the easiest to cure in its early stages. Travellers themselves have a per- sonal responsibility to recognise the health risks of travel, and they should bear in mind that a journey between two countries may involve unexpected deviations to a third country. Self-protection As a traveller, how can you protect yourself against malaria? Information on whether there is malaria risk in a certain area at a certain time, as well as advice on protective measures, should be sought from the national health administration of the traveller's home country, which can call on the medical profession, tourist agen- Mosquito eggs and larvae form a deceptively pretty pattern. (Photo WHO) cies, shipping companies, airline operators and other bodies for aid. All of these should be able to provide this information. It is based mainly on data provided to voio by the malarious countries and pub- lished in two booklets, Information on malaria risk for international travellers (obtainable free from the Malaria Action Programme, vsmo, Geneva) and Vaccination Certifi- cate Requirements for International Travel and Health Advice to Travell- ers, 1982, (available from Distribu- tion and Sales Service, WHO, Geneva, or from local agents, at the equivalent of 12 Swiss francs). International travel guides used by airline operators and travel agents, and leaflets issued by health auth- orities and medical associations also include this information. Apart from protection by chemo- prophylaxis for malaria, the main precaution the traveller can take is to avoid situations where he or she may be bitten by insects, especially during the hours of darkness. The following measures are also recom- mended: Choose rooms with screens on windows and other openings so as to prevent mosquitos from entering; Use "anti-fly" spray containing pyrethrum insecticides to kill any mosquitos that may have entered in spite of screening; but the effect is rather short-lived, and the spraying must be re- peated frequently if mosquitos continue to enter; If the entrances to bedrooms are not screened, the use of cloth mosquito nets around the beds at night is advisable, especially for babies and young children; it is essential to tuck in the net carefully under the mattress, and the net should have no holes; After sunset, all persons staying in the open should wear suf- ficient clothing to protect the body from mosquito bites (long sleeves, long trousers and so on); smear uncovered parts of the body with an insect repell- ent, such as dimethylphthalate; but the lasting effect of these products is only two to three hours and they must be re- applied. Bear in mind that in many countries where there is malaria, the main towns are often free of the &ease, though this is not necessari- ly true of the outskirts. While there is usually much less risk of malaria at altitudes greater than 1,500 metres above sea level, the disease can occur in certain climatic con- ditions at much higher elevations. The degree of risk of infection varies with the season. If you are in any doubt about malaria, it is wise to take precau- tions anyway and equip yourself with the recommended drugs. And on your return home, if you feel ill, don't forget to tell your doctor about any recent international travelling you have done. ■ 10 Keeping insects at bay In warm and tropical countries, travellers rarely have time to identify just what has bitten them and where. The best defence is to prevent any insect from getting a bite by Alec Smith aintaining good health while travelling is not just some- thing that matters to af- fluent visitors from wealthy developed countries. It is of vital concern to many developing coun- tries which are in the process of building up a tourist industry as part of their economic infrastruc- ture. This is a labour-demanding industry, providing employment for many people in all walks of life, and is also an important source of foreign exchange for some develop- ing countries. While tourism embraces some highly specialised interests, the bulk of it is concerned with holiday- makers' search for sun and water- side scenes. Even the "culture- vultures" heading for sites of early civilisations find that many of them are located in sunny climes near major rivers. So the tourist is predisposed to holiday-making close to the breeding places of mosquitos and other biting insects, such as midges, that tend to breed profusely in a warm aquatic envi- ronment. In many tropical countries, and in warmer parts of the temperate zone, the local Anopheles mosquitos may be carriers of malaria. This is the most important insect-borne disease that all travellers in warm countries—whether on business or pleasure—should worry about and take appropriate precautions against. Yellow fever is another important mosquito-borne disease in tropical Africa and parts of South America; visitors to countries where the disease may occur are advised to have a prior inoculation against yellow fever if there is the slightest possibility of travelling outside the main towns. Over large areas of the Volta River basin in West Africa, bites from the blackfly Simulium damnosum can transmit the disease of onchocerciasis—"river blindness". (Photo WHO/D. Deriaz) In most non-tropical places, the local mosquitos are not vectors of disease, but in late spring and summer months travellers, not only in Mediterranean but also in Arctic latitudes, may be plagued by swarms of these insects. In certain temperate areas, such as the North American continent and south- ern Australia, mosquitos (Culex) are vectors of viral encephalitis diseases. In hotels in warm countries which do not have air-conditioning, win- dows are often left wide open in the evenings to let cool air circulate; visitors have to rely on mosquito- mesh over the window-frames and mosquito-nets over the beds. These measures, while valuable, are often not fully effective and, since the insects generally prefer to bite below knee-level, it is advisable to wear mosquito-boots or at least slacks or a long dress in the evening. Some mosquitos, including certain malaria-carrying species, are largely outdoor biters, so these precautions are particularly essential in the open air. Then there are the mosquito species that prefer to bite in the daytime. The classical vector of urban yellow fever and dengue or breakbone fever, Aedes aegypti, is an example. It occurs, worldwide, in tropical regions but, in most areas, is only a nuisance, biting people who stand or walk in well-shaded places. Applying a mosquito repell- ent such as deet or dimethyl- phthalate (DMP) to the exposed parts of the skin usually gives adequate protection; but be careful in using them while wearing certain synthet- ic fibres which may be dissolved by the repellent. In some areas such as the great papyrus swamps of Africa, vicious biting mosquitos of the genus Mansonia may be present in great numbers, day and night; they can even bite you through the 11 canvas of a deck chair. The only advice for the traveller is to avoid such places! Two other groups of biting in- sects, closely associated with water- side situations, are biting midges (Ceratopogonidae) and blackflies (Simuliidae). Both these groups are tiny insects, and are widely distri- buted throughout the world in cold as well as hot countries. In certain tropical areas they transmit a par- asite that lives in the blood or the skin of man; some species of biting midges cause a filariasis called dipetalonemiasis, and certain black- flies the disease of onchocerciasis. The latter disease can lead to serious disability among indigenous people in the form of "river-blindness", but this is a cumulative disease, only manifested after years of exposure to infective bites, and consequently does not represent a hazard to the short-term visitor. Biting midges are at their worst at dawn and dusk, but are also active throughout the day. They can plague the country-walker in swampy areas and tourists on other- wise idyllic beaches. Blackflies breed in rapidly flowing clean water and can be a great nuisance to fishermen and canoeists as far north as Canada and Scandinavia as well as in some tropical countries. Travellers can best protect them- selves against both groups of pests by applying insect repellent to the exposed parts as frequently as necessary and, if camping out, by sleeping under a net with a very fine mesh. Tourists going on "safari" to see wild game usually do so during the dry season when the grass is dry and flattened, the deciduous trees bare of leaves and the game concentrated around water-holes. This is the best time to see the animals, certainly, but it does expose the visitor to various biting flies and ticks. Sand- flies (Phlebotomus) are minute insects that live near sandy river- beds or even around dwelling houses. They bite in the shade in daytime and at dusk, and can transmit sandfly fever which is not a serious disease but can cause nasty headaches for a few days. They are also vectors of leishmaniasis, which is more serious, but short-term visitors are unlikely to catch this. Personal protection is as for biting midges. The tsetse fly (Glossina), found only in Africa, is a vicious biter in daytime and has the unwelcome habit of following rapidly moving objects such as vehicles and—in some instances—people. A safari vehicle may be pursued by a cloud of tsetse which will fly in and bite the occupants unless all windows are closed. If the occupants are not to be uncomfortably hot, a canister of aerosol insecticide should be kept at hand in the vehicle and the interior sprayed briefly from time to time to kill the tsetse that have entered; the windows can then be opened at intervals. As tsetse can bite through thin clothing, it is advisable for the traveller to wear a safari suit of heavy material. Insect repellents also give some protection. The tsetse is a notorious vector of animal trypanosomiasis and of human sleeping sickness. One species is particularly associated with water, and a shady tree beside a pond or stream can be a particularly dan- gerous area. Human sleeping sick- ness is a serious disease and it is better, wherever possible, to avoid entering infected areas. The tabanid flies, which include horseflies (Tabanus), clegs ( Haema- topota) and deerflies (Chrysops) are found worldwide. They are quite large day-biting flies which, while they do not usually occur in great numbers, characteristically approach silently and deliver a sharp piercing bite, especially those of the genus Pangonia which has a long needle-like proboscis. Clothing of heavy material affords some protection. Travellers in temperate countries during the summer months may be pestered, particularly during cloudy or sultry weather, by stable or storm flies (Stomoxys). In appearance, these resemble houseflies but differ in having biting mouth parts cap- able of piercing light clothing. They breed extensively in the dung of domestic animals. They can also be a nuisance in the tropics, where there are large herds of cattle. Stable flies mostly bite people around the ankles, but socks or stockings give 12 Aedes aegypti, the mosquito which carries urban yellow fever. A collection of ticks, the vectors of various virus diseases. Female blackfly, the pest which transmits "river blindness". Tsetse fly, a vicious biter and the vector of sleeping sickness. (Photos WHO) 4 inadequate protection. The best personal protection is to apply a repellent to the legs, or to wear socks or stockings made of natural fibres. Houseflies (Musca domestica) can be a great pest to the perspiring traveller. A repellent ointment or cream applied to the face (avoiding the mucous membranes of eyes, nose and lips) gives protection. If the housefly nuisance is indoors, where there is a danger of contami- nating food, the remedy is to spray the room with an insecticide and to make sure that all food is kept covered. Repellents such as deet or in- dalone should be applied to socks and legs of travellers in tropical grasslands, particularly where cattle graze, as the grass stems may be covered with the tiny nymphs of cattle ticks (Rhipicephalus) and mites. The "seed ticks", as they are called, are almost invisible to the naked eye; they seek out the moist warm parts of the body behind the limb joints and bury their mouth parts into the skin, causing a persistent and painful smarting or burning sensation, particularly at night. Ticks can transmit several diseases to man, particularly viruses which cause various forms of "tick fever" some of which are relatively benign but others more serious. They may also cause a transient paralysis. In Canada and North America, ticks (Dermacentor, Amblyomma) transmit the serious rickettsial dis- ease of Rocky Mountain Spotted Fever which leads to some five per cent mortality each year among those who contract it. It also occurs as "Spotted Fever" in Central and South America. The disease is most prevalent in the western United States and Canada in April and June, and in the eastern United States in summer. Hunters and hikers frequenting infected areas should wear long trousers tucked into their boots and other suitable clothing to avoid tick bites. Ap- plication of tick repellents to the clothing and exposed parts of the body, and a change of garments before retiring to bed, will also help to avoid infection. While the average traveller may be assured of a good night's rest in well-run hotels, less salubrious and less hygienic accommodation may on occasions be unavoidable. Bed- bugs or fleas rarely cause diseases, but may give rise to a sleepless night. Bed-bugs are thin, flat, nocturnal insects capable of running rapidly over exposed skin without being felt; their bites made at random, usually on or near the feet, develop into large red weals. Fleas, as is well known, are very small insects which jump when disturbed. Their bites characteristically occur three in a row, where clothing fits tightly to the body, and generally result in small raised spots. A bed infested with bed-bugs requires professional disinfection and should be aban- doned as soon as possible. But a flea-infested bed can be rendered serviceable by hunting out, hand- catching and destroying as many fleas as possible, and then applying insecticide powder betweeen the sheets; unlike bed-bugs, fleas are very susceptible to most insec- ticides. Besides these personal precau- tions that the traveller can take, governments and municipalities can apply a number of public health measures to protect visitors from insect pests and vectors of disease. These include: siting tourist recreation areas away from large natural breeding places of mos- quitos; installing and maintaining a good water supply and solid and liquid waste disposal systems, so as to minimise the formation of breed- ing sites for pests; checking on, and insisting on, high standards of hygiene in hotels; applying mos- quito abatement measures; ensur- ing that game parks are free from serious vector-borne diseases, or at least present a minimal risk to visitors; notifying travellers of seas- onal health risks and providing appropriate advice. And, of course, in view of the tremendous growth in international travel that has taken place in the last two decades, governments and air- lines share a responsibility for ensuring that harmful insects are not transported by aircraft into countries where they did not previously live. ■ 13 ril Travellers' diarrhoea The best way of preventing diarrhoea is to avoid exposure to the infective agent. If you do contract diarrhoea, the mainstay of treatment is the use of oral rehydration fluids by R.H. Herniman it here is nothing new about diarrhoea. It is a condition that has afflicted travellers from time immemorial. But what is new today is the tremendous increase in the numbers of people travelling and the distances they travel. There are few places in the world that cannot be reached in 24 hours. If we count tourists alone, there are more than 500 million people travelling each year, and anyone who travels is liable to get diarrhoea. The experience is all too well known: the journey, the excitement of arrival in new and foreign places, the exotic foods and drink, and then the uneasiness, the abdominal cramp and the sudden emergency rush towards the toilet (if one is lucky enough to be near one). Then the business of being ill in a strange place, the misery of being confined to a hotel room while work is unattended or a holiday ruined. Travellers' diarrhoea can cover a wide range of conditions from food poisoning to cholera. In general we can describe it as an illness of sudden onset with watery diarrhoea more than three to four times a day, often with abdominal cramps, nausea, vomiting and even fever. The illness can sometimes last up to a week and will then subside, even if no treatment is given. This is perhaps the most common form, but there are variations, from the very mild attack with one or two loose stools to an extensive diarr- hoea with vomiting and collapse. Travellers' diarrhoea isn't caused by a change in climate, or by exposure to draughts, or by air conditioning. It results from an infection, usually picked up from contaminated food or water—and of course local residents are equally exposed to it. The commonest cause of the infection is one of several types of the bacteria Escherichia coli, Traditional midwives in the Philip- pines learn how to prepare oral rehydration fluids for the treatment of diarrhoea. Facing page: Hot-dog stall lures the passer-by in Guatemala. The com- monest cause of travellers' diarrhoea is contaminated food or water. ( Photos WHO I J. Abcede and WHO/ P. Larsen) but other bacteria may also be to blame, such as Shigella (it can cause dysentery) or Salmonella, or those causing food poisoning (e.g. Staphylococcus aureus). Viruses may also be the culprit, as well as bigger intestinal parasites such as Entamoeba hystolytica (causing amoebic dysentery) and a parasite with two tails called Giardia lamblia. So the causes of travellers' diarr- hoea are many. From the patient's point of view, the cause is not so important as the treatment, which we will mention later; but from the health authorities' point of view it is important to know the causes of the diarrhoea since they can also be responsible for endemic illness in the population and even for large epidemics. Strange food Many travellers blame strange food and a change of diet for their diarrhoea, and there is good reason for this. After all, as we have mentioned, food and water may carry the infecting agent, especially where hygiene is poor. But in addition travellers in strange places may relax their own code of cleanli- ness and take risks they would not take at home. In a holiday environ- ment, people tend to drink too much alcohol and eat large heavy meals that they are not used to. All this may dilute the acid in the stomach which acts as a natural defence against infection and, with the defences down, the infection can gain entry to the intestine and start its painful work. Certain travellers are at special risk. Anyone taking antacids or drugs for ulcers is susceptible, since these drugs also neutralise the protective acidity of the stomach. Diarrhoea is potentially more serious in young children and older people, who can quickly become severely ill due to loss of body fluid 15 and salts. The same would apply to persons with a metabolic disorder such as diabetes, or to heart cases receiving treatment, especially those taking diuretic drugs or digitalis. The risk of getting travellers' diarrhoea depends on where one travels. Areas where standards of food hygiene are not high, and where there is already a high incidence of diarrhoeal disease in the population, are more likely to be associated with travellers' diarr- hoea; but a traveller from one high incidence area to another is not so likely to be affected as he may have built up immunity to the offending agents. The traveller most at risk is one who travels from a low incidence area to a high risk area. Having been attacked by diarr- hoea, what should the traveller do about it? There are many suggested treatments for this age-old malady. The first and most important thing to remember is that the danger in diarrhoea is dehydration, that is to say loss of body fluid and salts caused by the diarrhoea. From the patient's point of view, the vital thing is to replace the fluid and salts lost. This is particularly important in children and older people. The fluid and salts can perfectly well be replaced by mouth, even if the patient is vomiting; however, where vomiting is severe or loss of fluid excessive, it may be necessary to use intravenous fluids under proper medical supervision. wHo recommends a special mixture known as oral rehydration salts (oRs), packets of which are widely distributed in developing countries with the assistance of UNICEF. The mixture recommended by WHO con- tains, in each sachet: 3.5 grams sodium chloride; 2.5 grams sodium bicarbonate; 1.5 grams potassium chloride; and 20 grams glucose, all to be dissolved in one litre of potable water. ORS preparations with these or similar ingredients are available in almost all countries. If they are not available, the traveller should at least drink plenty of fluid in the form of thin soup, weak tea, or some bland drink such as barley water, with a little salt and sugar added. Highly sweetened and acidic drinks should not be taken. In the case of infants and children, some feeding should be maintained, par- ticularly breastfeeding of babies. In most cases, maintaining a high fluid intake, preferably with an oral rehydration mixture, is all that is needed until the diarrhoea stops. There is no evidence that drugs play much part in curing travellers' diarrhoea except under certain spe- cific conditions. This is a rather controversial area, since a vast number of commercially available "anti-diarrhoea agents" are on the market. It is doubtful whether any of these really cure the diarrhoea, although they may temporarily reduce its severity and relieve symptoms. Let me be more specific. Anti- Pilgrim tents dot the plain as far as the eye can see near the Moslem holy city of Mecca, in Saudi Arabia. Prevention of diarrhoeal outbreaks is vital in these circumstances. Facing page: Primitive sanitation in a rural community of South-East Asia. Overcoming this kind of problem is one of the targets of the International Drinking Water Supply and Sanitation Decade, 1981-1990. ( Photos WHO and WHO/ UNICEF) biotics are of value only for cholera or for frank dysentery due to shigellosis (or amoebiasis). There is also a specific drug for giardiasis. A number of anti-diarrhoea drugs are available for the relief of abdominal cramps, and these may be helpful in some adults who for convenience desire temporary relief of symp- toms, but they should only be taken for a day or two and should never be given to children, older persons, or anyone with dysentery. There is some evidence that drugs, such as bismuth subsalicylate, which help prevent the secretion of the diarr- hoea fluid from the intestine may be useful, but more experimental work is needed to find this out before their use can be recommended. There is little evidence that any other preparations or combinations are useful. So the mainstay of treatment should be oral fluids. If relief is not rapid, then medical help should be sought and the appropriate addi- tional therapy should be given under medical supervision. Although rapid and effective treatment is of great concern to the individual traveller, it is equally important for the health authorities to try to prevent travellers' diarr- hoea from occurring. In the present era of jet travel, tourism is par- ticularly affected. Tropical coun- tries trying to develop their tourist industry are very conscious of the need to prevent diarrhoeal out- breaks. For athletes in competition, for pilgrims, and for businessmen, prevention is vital. The best way of preventing travellers' diarrhoea is to avoid exposure to the infective agent. To do that, food and water must be clean and standards of personal and environmental hygiene must be adequate. Public health authorities in countries with a high incidence of diarrhoea should ensure that a good standard of food and water hygiene is maintained in establishments serving travellers. To support this, it is necessary to have adequate lab- oratory facilities, so as to be able both to perform the necessary checks on food and water, and to identify the causative agent when any outbreaks of diarrhoea occur. What can the individual do to prevent diarrhoea while travelling? First and foremost, it is prudent to reduce the risks as much as possible: eat clean food, drink clean water. This means in fact drinking only water that is boiled or bottled (be sure it is carbonated), tea or coffee made with boiled water, or other carbonated beverages, and eating only food that has either been well cooked immediately before serving, or is protected from infection (that is to say, food from tins). Beware of salads and avoid them if at all possible. There is some evidence that taking prophylactic antibiotics may be of some value. However, if they are used at all, they should be used only by adults travelling for a short period (less than three weeks) to high-risk areas where it is imposs- ible to obtain safe water and food. This would especially apply to persons with conditions associated with decreased gastric acidity or other serious conditions. Moderation in all things is a good motto, and this applies to travell- ing: eat and drink sensibly, do not take risks, and—if the worst happens—then be prepared and have some oral rehydration mixture handy. ■ , Viral hepatitis Jaundice has been a familiar disease since classical times. Today three main forms of viral hepatitis are recognised, which threaten the health of travellers all over the world by Arie J. Zuckerman iral hepatitis, an acute in- flammation of the liver, has emerged as a major public health problem occurring en- demically throughout the world. "Epidemic" jaundice was recognised by Hippocrates and the early Greek and Roman writers, and the huge epidemics in times of war, referred to as "cam- paign jaundice", affected not only military strategy and the course of war but also the civilian population. Pro- gress in the understanding of viral hepatitis was slow until 1967-68, when a specific laboratory marker for one form—hepatitis type B (causing serum hepatitis)—was identified. Hepatitis A virus, the cause of infectious hepatitis or jaundice, was recognised five years later. Both types of infection are very common in hot-climate countries, in the developing countries and in some areas of Europe. More recently, a third form of infection, referred to as non-A, non-B hepatitis, has been found in all countries in which it has been sought. Hepatitis A The exact incidence of hepatitis A is not known because of the high propor- tion of infections without clinical symptoms and infections without jaun- dice (a yellowing of the skin and of the Provided syringes and needles are sterilised, they should pose no risk of transmitting the hepatitis B virus. Tests for markers of this virus have been introduced for the screening of all blood for transfusion. Inset: The complex structure of the virus seen under an electron-microscope. (Photos WHO/ E. Rice and WHO/ A. Zuckerman) whites of the eyes), compared to the typical illness with varying degrees of jaundice. Although the disease has, in general, a low mortality, patients may be incapacitated for many weeks. There is no evidence of the infection persisting, nor of a progression to chronic liver damage. The highest incidence of hepatitis A in the develop- ing countries is observed in children of school age; but in North America, in many countries of northern Europe and in Australia, most cases now occur in adults and the prevalence of the infection is decreasing. Hepatitis A virus is spread by the faecal-oral route, usually by person to person contact, and the infection is particularly common in conditions with poor sanitation and overcrowd- ing. The incubation period is about 28 days. Outbreaks result most frequently from faecal contamination of drinking water and food, but water-borne trans- mission is not a major factor in the industrialised countries. On the other hand, many food-borne outbreaks have been reported in recent years and these are becoming important epide- miologically in the developed coun- tries. This can be attributed to the shedding of large amounts of virus in the faeces during the incubation period of the illness in infected foodhandlers, and the source of the outbreak can often be traced to uncooked food or food that has been handled after cooking. The consumption of raw or inadequately cooked shellfish cul- tivated in water polluted with sewage is associated with a high risk of infection. Hence it is frequently contracted by non-immune travellers who are unwise enough to eat such food in less-than- hygienic circumstances. Hepatitis A is rarely, if ever, trans- mitted by blood and blood products, or by skin penetration. Control of the infection is difficult. Since faecal shedding of the virus is at its highest during the incubation period and early phase of the illness, strict isolation of cases is not a useful control measure. The best means of reducing the spread of infection is by ensuring simple hygienic measures and the sanitary disposal of excreta. Normal human immunoglobulin, prepared from pooled plasma of heal- thy blood donors, given intramuscular- ly before exposure to the virus or early during the incubation period, will prevent or attenuate a clinical illness, but does not always prevent infection and the excretion of virus. The efficacy of passive immunization depends on the presence of hepatitis A antibody in the immunoglobulin, which is used most commonly for close personal contacts of patients with hepatitis A, particularly household contacts, and for those exposed to contaminated food. Prophylaxis with immuno- globulin is recommended for people going from a low risk to a high risk area. The successful propagation of hepatitis A virus, in 1979, in cell cultures and in continuous cell strains of primate origin has opened the way to the preparation of hepatitis A vaccines, and these are now under development. Hepatitis B The importance of hepatitis B can- not be exaggerated. Apart from the acute illness, which varies in severity, the infection, especially in children infected at or around the time of birth 19 or early in life, may persist. At present, it is conservatively estimated that there are 200 million carriers worldwide. In addition, infection with hepatitis B virus may progress to chronic liver disease, including chronic active hepa- titis and cirrhosis, and there is evidence of a compelling association between hepatitis B virus and primary liver cancer, which is one of the world's most common tumours. In the past, hepatitis B was diag- nosed on the basis of infection occurring about 60 to 80 days after blood transfusion, the injection of human plasma fractions or the use of inadequately sterilised syringes and needles. The availability of specific laboratory tests for hepatitis B markers has confirmed the importance of trans- mission by skin penetration, and infectivity appears to be especially related to blood. But hepatitis B is not spread exclusively by blood and blood products; for example, under certain circumstances the virus is infective by mouth. This disease is more prevalent in adults living in urban communities and under poor socio-economic conditions. There is plenty of evidence for the transmission of hepatitis B by intimate contact and by the sexual route. People who are sexually promiscuous, par- ticularly male homosexuals, are at very high risk. Antigens of hepatitis B have been found in blood and in various body fluids such as saliva, menstrual and vaginal discharges, and seminal fluid, all of which have been implicated as vehicles of transmission of the infection. It is not surprising, therefore, that contact-associated hepatitis B is of major importance. Transmission of the infection may result from accidental inoculation of minute amounts of blood or fluids contaminated with blood. This may occur during medical, surgical and dental procedures, immunization with inadequately sterilised syringes and needles, intravenous or percutaneous drug abuse, tattooing, ear piercing and nose piercing, acupuncture, laboratory accidents or accidental inoculation with razors and similar sharp objects. In some countries, there may be further local risks from traditional tattooing and scarification, blood let- ting and ritual circumcision, and from Viral hepatitis Left: People who are sexually promis- cuous, particularly male homo- sexuals, are at very high risk from hepatitis B. Right: Transmission of this virus disease, resulting from accidental inocula- tion of minute amounts of blood or fluids contaminated with blood, may also occur during medical, surgical and dental procedures, intravenous drug abuse, ear and nose piercing, or tattooing. ( Photos L. Sirman repeated biting by blood-sucking insect vectors. Hepatitis B antigens have been detected in several species of mosquito and in bed-bugs which have either been trapped in the wild or fed experiment- ally on infected blood, but there is no evidence yet that they actually transmit the disease. Transmission of hepatitis virus from carrier mothers to their babies can occur during the perinatal period, and this appears to be an important factor in determining the prevalence of infec- tion in some regions. There is also an increased risk of perinatal infection if the mother has acute hepatitis between the third and ninth month of pregnancy or within two months after delivery. A high proportion of children infected during these periods become persistent carriers. We call people carriers if the infec- tion persists in their blood circulation for more than six months. They may continue to be carriers all their lives and seem to be at risk of chronic liver disease. More men than women become carriers. The survival of the hepatitis B virus is ensured by the vast reservoir of 20 carriers in the general population. We find a prevalance of around 0.1 per cent in northern Europe, North America and Australia, up to five per cent in central and eastern Europe, and a higher frequency in southern Europe, the countries bordering the Mediter- ranean and parts of Central and South America. In some parts of Africa, Asia and the Pacific region, as many as 20 per cent or more of the apparently healthy population may prove to be carriers. Obviously a vaccine to protect both travellers and residents against hepa- titis B is needed urgently. In order to prepare conventional viral vaccines it is necessary to cultivate the virus in cell culture; but to date all attempts to grow hepatitis B virus in tissue culture have met with failure. Research is therefore turning towards other preparations for active immunization, including the use of inactivated hepatitis B surface anti- gen purified from the plasma of healthy human carriers of the virus. Such a vaccine has been tested for safety and efficacy, and successful clinical trials have recently been completed. Future developments include using the techni- ques of genetic engineering for large scale production of immunogenic pro- teins, and there has been some progress in perfecting the chemical synthesis of vaccines in the laboratory. Non-A, non-B hepatitis Non-A, non-B hepatitis has been found in every country in which it has been sought, and it has been most frequently recognised as a complica- tion of blood transfusion and after the administration of blood clotting fac- tors. However, specific laboratory tests for identifying it are not yet available and it is likely that several distinct viruses are involved. This type of hepatitis has occurred in haemodialysis units (where patients with kidney disease have their blood artificially cleansed) and in other specialised hospital units, among drug addicts and after accidental inoculation with conta- minated needles and other sharp objects. In several countries, a significant number of cases are not associated with transfusion; such sporadic cases of non-A, non-B hepatitis account for 10 to 25 per cent of all adult patients with recognised viral hepatitis. The route of infection or the course of infection cannot be identified in many of these patients. In addition, there are now convincing reports of the existence of an epidemic strain of non-A, non-B hepatitis virus, transmitted by conta- minated water in the subcontinent of India. A study of one such epidemic in the Kashmir Valley revealed that the infection was more frequent and more severe in pregnant women than in the general population, and it was asso- ciated with a high mortality rate during pregnancy. Although this illness, as described in Europe and in North America, is usually mild and often without jaun- dice, severe hepatitis with jaundice does occur and the infection is a significant cause of fulminant hepatitis. There is considerable evidence of the prolonged presence of the virus in the blood and the development of a persistent carrier state. Chronic liver damage may occur in as many as 40 to 50 per cent of the patients after infection associated with blood transfusion or with treatment by haemodialysis. ■ 21 Is it safe to eat? by John Bland Lt ithin the past ten years, three of the most serious outbreaks of food poison-ing affecting airliner pass- engers involved: ham omelettes contaminated with staphylococci from a chef's infected finger; prawn cocktails contaminated with Vibrio parahaemolyticus from cabin staff who had handled raw shellfish and not subsequently washed their hands; and mayonnaise prepared with eggs contaminated with sal- monellae. The latter incident resul- ted in several deaths. It is reassuring to consider how truly rare such incidents are when we recall how many hundreds of millions of passengers each year climb aboard airliners and are served appetising meals at heights above sea-level to which, a few decades ago, only Himalayan clim- bers could aspire! Think of the problems and poten- tial hazards involved. Imagine a jumbo jet arriving at a European airport with 100 passengers who have travelled from a cholera- endemic country in Asia. Now 200 more passengers join the flight—but fog closes the runways for three hours before the plane can take off for a third destination in North America. How do you ensure that the original cabin crew left no contaminating focus of cholera vibrio, that the human wastes after the long flight are safely disposed of, that the 300 delayed meals which the passengers will expect high over the Atlantic are 100 per cent free from the risk of salmonellosis, that no insect vectors of disease spread infection across three continents? We might call it a daily miracle for every 24 hours that pass without such disasters coming to pass. But of course this "miracle" depends on the high sense of responsibility shown by airline operators, aircraft staff, the caterers, the ground crew and so on. These examples concern airliners, but the same principles apply equ- ally to ocean travel and to long- distance train and coach journeys. If it were possible to evaluate precisely the risks due to food-borne illnesses, it is probable that the passengers on our imagined three-continents flight would be less exposed to danger than the family that sets off for a bus ride or car ride of 200 miles and stops twice at roadside cafés. Tourists are not the only travell- ers for whom food safety is a vital concern. The mass travel of pilgrims to holy places, the international coming and going of millions of workers in search of employment, the routine passage of thousands of merchant seamen between ports in every continent—all these involve food and hygiene risks that have to be kept to a minimum by the responsible authorities. Two of the key provisions of the International Health Regulations, to which virtually all countries of the world are signatories, are that: Every port and airport shall be provided with pure drinking-water and wholesome food supplied from sources approved by the health administration for public use and consumption on the premises or on board ships or aircraft. The drink- ing water and food shall be stored and handled in such a manner as to ensure their protection against contamination. The health author- ity shall conduct periodic inspec- tions of equipment, installations and premises, and shall collect samples of water and food for laboratory examinations to verify the observance of this Article... Every port and airport shall also be provided with an effective system for the removal and safe disposal of excrement, refuse, waste water, condemned food, and other matters dangerous to health. WHO itself has no responsibility for the enforcement of health re- gulations, or for the conduct of health within any specific country. Its role in the field of environmental sanitation is to assist national health administrations to institute and execute adequate programmes of sanitation. The Guide to Ship Sanitation, published by WHO in 1967, is intended to bridge the gap between legal requirements and their actual application, and provides practical recommenda- tions for such measures as the protection of potable water from contamination and the preservation of food quality. Similarly the Guide to Hygiene and Sanitation in Avia- tion, published in 1977, is intended to help those administrations as well as aviation and airport authorities, air transport operators, airport and airline caterers and employees, airport designers and aircraft manufacturers. In its 150 pages, this Guide goes into fine detail about all aspects of food preparation, handling and serving, safeguarding water sup- plies, toilet sanitation and liquid wastes disposal, dealing with solid wastes, cleaning the interior of aircraft, cargo-carrying, and the control of insect pests and other disease carriers. The frightening notion that both pilot and co-pilot might fall ill from food poisoning has inspired a num- ber of sensational novels and films. wHo's Guide makes this recom- mendation: "When flight deck personnel eat during the flight, it is absolutely essential that the captain should be given a completely dif- ferent meal from that served to the 22 co-pilot, prepared from food ob- tained from different sources. The same principle must apply if they eat in ground catering premises a few hours before take-off. This is an essential safety precaution to reduce the possibility of their both eating food contaminated by a pathogen that causes a disease with a short incubation period to which they might succumb during the next flight." Although regular medical exam- ination of people who handle food, whether in the air, at sea or on land, is a legal requirement in many countries, it is even more important to train these people to wash their hands frequently and to practise basic hygiene. This was the main conclusion reached by a Working Group on Health Examinations for Food-Handling Personnel which met at wHo's Regional Office for Europe in November 1979. The group concluded that physical ex- amination of the food handler was of very limited value in detecting carriers of infection. Its report suggested: "All food handlers must appreciate their responsibility and continually practise the highest level of hygiene, for which proper train- ing is needed. They must also be aware of the need to report any illness, especially affecting the skin, the upper respiratory tract and the gastro-intestinal tract. They must understand the modes of trans- mission and the significance of food poisoning organisms, in order to be motivated to maintain hygienic practices and report illnesses." So what can caterers do to ensure that the food they serve is safe? Here are some suggested "rules" : Cooking: Thaw frozen meat and poultry completely before cooking, separate from other foods. Do not undercook food. Use separate surfaces, utensils and other equipment for preparing raw and cooked food. Take particular care when cutting up cooked food. Cook it as near as possible to the time it must be served. Avoid re-heating food, but if there is no alternative, it must be reheated thoroughly throughout. — Cleaning: Use a good detergent A picturesque street scene in Asia, where travellers may be tempted to eat at little tables set out in the street. National health authorities have a big responsibil- ity for ensuring that food handlers, everywhere, maintain high standards of hygiene. ( Photo WHO/T. Takahara) to clean vessels and surfaces, and disinfect with hypochlorite. Dry all surfaces and equipment well. Boil cloths, mops and brushes at the end of each day—or better still use an autoclave—and store them dry. Take particular care with sinks and taps, clean them frequently and disinfect them from time to time. Storage: Keep food really hot or cold (preferably five degrees centi- grade or below), as required, and take particular care with meat, cream and mayonnaise. Handling: Wash hands after handling raw foods. Discourage the handling of cooked foods. Finally, what can travellers them- selves do to protect themselves from gastro-enteritis and other food risks? Firstly, where possible eat foods that have been freshly cooked and served hot—and if you have any doubt about their safety, avoid such foods as ice cream, soft cheeses, cold meats, shellfish and other sea-foods, salads and soft- skinned fruits. Secondly, avoid drinking or cleaning teeth in cold water unless it is known to be chlorinated. Thirdly, avoid using ice unless you know safe water was used to make it. ■ 23 F: 4 Regional distribution of some arboviruses that may threaten the traveller Dengue and pseudo-dengue Haemorrhagic fever Encephalitis North Africa Rift Valley fever West Nile (Egypt), Sandfly fever, West Nile, Sindbis Tropical Africa Chikungunya, O'nyong-nyong, dengue, Zika, Rift Valley, Orungo Yellow fever, Crimean and Congo haemor- rhagic fever* North America Colorado tick fever Eastern equine, Western equine, St. Louis, California Central America and tropical South America Dengue, Mayaro, Mucambo, Sandfly fever, Murutucu, Oropouche Yellow fever St. Louis, equine encephalitis of Venezuela, Ilheits, Rocio type Tropical Asia Chikungunya, Sindbis, dengue, Sandfly fever, Zika Chikungunya, dengue haemorrhagic fever Japanese B encephalitis Central Europe and Sandfly fever, Mediterranean West Nile Tick encephalitis Middle East West Nile, Sandfly fever Crimean and Congo haemorrhagic fever West Nile Western Pacific Sindbis, Ross River Dengue Japanese B fever, dengue haemorrhagic fever encephalitis, Australian encephalitis * Under this heading come the Lassa, Marburg and Ebola fevers. Viruses transmitted by insects Every tourist suffers at some time from insect bites. Certain insects, unfortunately, can cause more than just a temporary irritation — so it is wise to take some elementary precautions by P. Bres L ike bacterial and parasitic infec-tions, virus diseases are transmitted to man by another infected person, in water or food, and by insect bites. Virtually no country in the world is free from viruses transmitted by insects, but they occur more frequently in hot countries or in the hot season generally. Such viruses therefore represent a risk not only for people who live in such regions but also for those who travel there for business or pleasure. Which insects are the culprits? Mainly they consist of mosquitos, phlebotomines (yellow sandflies), the Culi- coides (midges and gnats, which fly in huge swarms and cause irritant bites), and ticks. To be precise, entomologists do not consider ticks as insects, and they are classed among the Arachnida (which also include spiders). Both insects and arach- nids are classed in the subkingdom of the arthropods. So the viruses we are talking about are called arboviruses, a contraction of the term "arthropod-borne virus". What viruses do they transmit? Insects can transmit a great many viruses through their bites either to man or to domestic and wild animals. By 1980, no fewer than 435 had been counted and the list is not yet complete. Fortunately, only about 100 of them cause diseases in humans. These viruses are named after the disease which they cause—such as dengue Ticks—the vectors of many virus diseases —are capable of international travel, as passengers on the bodies of migrating birds. Here, a research worker in India removes a tick from the head of a duck. ( Photo WHO/P. Almasy) fever and yellow fever where they were first Nile, Zika, and so on. Arboviruses cause diseases: dengue or dengue, haemorrhagic phalitis (see accompanying table). Since different viruses can cause the same symp- toms and since certain arboviruses can cause any one of these three diseases, it is vital to have access to a virology laboratory to determine which virus is involved. A or after the place discovered West three kinds of fevers resembling fevers and ence- 25 number of laboratories which specialise in these viruses have been designated as voto Collaborating Centres for reference and research. Dengue and diseases resembling dengue Essentially a tropical disease, dengue is all too well known to those travellers who have had the misfortune to suffer from it. The virus is most often transmitted by the Aedes aegypti mosquito. It starts with a sudden high fever, and in typical cases an intense general malaise sends the patient to bed, and is accompanied by violent head- aches, pains in the muscles and joints which prevent all movement, and digestive disor- ders; the course of the disease often occurs in two phases separated by a short period of remission. The patient invariably gets better, but convalescence is difficult and protracted. Other arboviruses, such as West Nile, Chikungunya, Ross River or Rift Valley fever, which are transmitted by different mosquitos, cause an identical disease but with less virulent symptoms. Others still are transmitted by sandflies and gnats, and cause diseases that resemble dengue. Yellow fever and haemorrhagic fevers One haemorrhagic fever has been known since ancient times; this is yellow fever, which cut swathes through the crews in the days of sailing ships and among the colonial planters of Africa and the Ameri- cas. Mortality can be as high as 80 per cent of serious cases. After two or three days of symptoms resembling dengue, a short period of calm follows; then bleeding begins from the gums and nose, with black vomiting and black stools as a result of internal bleeding in the digestive tract. Jaundice yellowing of the skin—is not very conspicuous, and death results be- tween the fifth and tenth day as a result of circulatory failure, sudden shock or coma. Since 1953, cases of dengue have begun to evolve in the same way as yellow fever in children aged from six months to 15 years in South-East Asia—this is dengue hae- morrhagic fever. We don't know why dengue changed its character so drastically Viruses transmitted by insects Left: The rat is suspected of having played an original role in the transmission to humans of di- seases caused by Lassa, Mar- burg and Ebola viruses, without the intervention of insects. Right: A round-up of horses in Eastern Europe. Equine encephalitis is a virus disease which affects both horses and man, and in Europe is carried by both mosquitos and ticks. ( Photos WHO/P. Boucas and WHO/MTI) from that date. Since then, dengue hae- morrhagic fever has spread to some countries of the Western Pacific and the Caribbean area. Other arboviruses, such as those which cause Crimean and Congo haemorrhagic fever, which is transmitted by ticks, provoke the same symptoms. Closely related to these haemorrhagic fevers are the diseases caused by Lassa, Marburg and Ebola viruses. These are new phenomena which have triggered off several serious epidemics in tropical Africa over the past ten years. In fact they are thought to have been transmitted originally from wild rats to humans without the intervention of insects, and are therefore not strictly speaking arboviruses; they also have the alarming characteristic of being commun- icable directly from one person to another. Encephalitis causes by arboviruses Japanese B encephalitis is gaining ground in South-East Asia and the Western Pacific because it is transmitted by mosquitos which abound in the rice fields. Symptoms of paralysis with spasms and contractions 26 appear five or six days after a general malaise is felt, more or less reminiscent of dengue. Encephalitis which affects both horses and man occurs in North, Central and South America, and is transmitted by mosquitos. It is also found in Europe, where it is carried by both mosquitos and ticks. An epidemic was recently caused in Brazil by a hitherto unknown virus, now called Rocio virus, and it too was trans- mitted by mosquitos. How serious are the risks? The insects and animals which enable these viruses to survive in nature through continuous cycles of transmission have a geographic distribution which is either regional (as in the case of yellow fever in America and tropical Africa), or spans several regions (as with dengue, which exists in all tropical areas). The risks for travellers are different in the towns and in the rural areas. In the towns, hazards arise from the arboviruses that are transmitted from person to person when an epidemic breaks out, as may happen with yellow fever, or when there is an endemic disease such as dengue. This kind of situation is well known to health authorities, and certainly should be well known to tourist agencies since the information is readily available from WHO. The risk is more difficult to assess in rural areas—which is precisely where safaris are organised for tourists wanting to see animals in the wild. In some places, the insect vectors and the vertebrate animals affected (such as horses, cattle, sheep, rodents and so on) may serve as hosts to an arbovirus whose presence has not hitherto been suspected or which only appears at irregular intervals. A tourist could therefore turn out to be the first unfor- tunate indicator of the presence of an arbovirus. This is always a potential danger, for example, with jungle yellow fever in Africa and in tropical America. What precautions can we take? There are as yet no anti-microbial drugs in current use which act as a defence against these viruses, therefore only preventive methods are possible. Vaccines have been developed which give protection against certain arboviruses: yellow fever, Japanese B encephalitis and Venezuelan encephalitis. The search is now on for a vaccine against dengue. A simple means of personal protection is to prevent all contact with winged or creeping insects through the use of insect re- pellents, either in vapour form or as creams applied to the skin, or by wearing special clothes as a defence against ticks. Certain chemical insecticides exist which instantly kill insects or have a long-lasting effect in powder form. Mosquito nets and grills need to have a very fine mesh in areas where there are sandflies and gnats. Ventilators and air conditioning help to keep winged insects out. In practice, the fact is that most travellers just don't know the health risks to which they are exposed, in particular as regards the arboviruses. Even if counter-precau- tions are not a hundred per cent sure or are difficult to put into effect, travellers ought to be warned—preferably by their travel agents and medical advisers before they set out on a journey about the possible risks and the available methods of protecti on. ■ 27 he extraordinary growth in the number of people on the move around the world is one of the key factors in the transmission of sexually-transmitted diseases (sDT). It is all too easy for travellers of all ages, whether on business or pleasure, of whatever ethnic group or of whatever social milieu, to contract such a disease—and all the more difficult to find and treat the person responsible for transmitting it. For a great many people, even those with a perfectly happy home life, going on a journey reflects a profound impulse to break away, an unsatiable curiosity, a yearning for new acquain- tances. Whatever the underlying motives, and whatever travelling entails—an intercontinental flight or just an exodus from a depressed rural area to the bright lights of the city—the consequences are an enormous number of cases of STD. The traveller entering an "exotic" society is not only han- dicapped by language barriers but is also more likely to fall easy prey to any sex-for-money offer. Among the general public, ignorance about these diseases continues to be almost total, and this is still the case even among doctors and other health personnel, who tend to show little interest in them. Two years ago, a study made in France showed that only 13.9 per cent of the people interviewed had any knowledge of STD; 35.3 per cent did not even know such diseases existed, and 50.8 per cent had some notion about them. In spite of all the efforts that have been put into research, there is still no effective vaccine against STD. Nor is there any wonder drug which would somehow shield the individual and protect him or her from an infection. Consequently, prevention is the only means at present of limiting their spread—prevention that must work at the individual level and yet must involve a collective effort. Wide publicity The first vital step therefore is to give the widest possible publicity to the facts of the situation. Everybody should be aware, for instance, that certain serious complications can result in sterility in both men and women, even in very young people. Today more that 60 per cent of cases of salpingitis (inflamma- tion of the uterine tube) are caused by these diseases and, of those so caused, 20 per cent of the women are likely to become sterile. There are a number of high-risk areas in the world, particular- ly in those countries—they exist in several continents—where what is known as "sex tours" are organized. This kind of information could be made available in simple brochures handed out at the same time as an air ticket or sailing ticket is sold. They should also go to schools, universities, military and naval units, tourist camp- sites; they could even be handed out to the drivers of cars and trucks at border crossing points. People need to be reminded of the elementary rules of hygiene which are too often forgotten these days—especially by women—since the appearance of modern contraceptive methods, including "the pill". It is essential to ensure the greatest possible cleanliness of the genital organs, and if necessary to use safe local antiseptics. For men, the preservative or condom is the best possible protection against urethro-genital infections of all kinds, provided it is properly used. Sweden sets a sensible example by distributing condoms widely among adolescent girls and young women for use by their partners. A variety of creams, lotions, pessa- ries and pills for women have been proposed for their antiseptic action, but without proof of their efficacy in preventing STD. Health education As regards collective efforts of prevention, health education is ex- tremely important in this field. One very essential point to be made is that it takes two (or more) people to pass on sexually transmitted diseases! Both partners should be treated at the same time, despite the fundamental dif- ferences between the sexes—that in men the clinical signs are usually apparent early on, while in women they remain hidden. Very often the woman does not know that she has caught an infection. It follows that as soon as a man realises that he has contracted STD, he should immediately warn his partner. In cases of fleeting sexual relationships during a journey, this may not always be possible. Homosexuals too constitute a high- risk group, particularly when they travel to places where homosexuality is less severely proscribed than in their home countries. They should have easy access to information about hospitals or dispensaries which specialise in STD control. The siren-song of seduction Sexually-transmitted diseases lie in wait for the traveller who is too casual about casual sex. Every effort of health education must be made to ensure that our potential traveller is both more prudent and better informed about STD by A. Siboulet 28 The traveller should start off by considering any new sexual partner as a potential carrier of a disease. The more partners are involved, the greater the risks. The incubation period, that is, the time elapsing between having sexual relations and the first clinical signs becoming visible, varies according to the disease. In the case of gonorrhoea, the indication of a genital discharge is classically said to appear in three to four days, but in fact this can often take 15 to 20 days or even longer. Again, for syphilis, incubation is generally con- sidered to be between 20 and 40 days, but in practice much longer periods of up to two or three months can occur. Not all genital discharges are caused by gonococcal infections. They may be due to tiny bacteria, such as Chlamydia trachomatis (although com- mon, this germ is hard to identify in many countries), to parasites such as Trichomonas vaginalis, to yeast-like fungi such as Candida albicans, or to a virus, like herpes. In all these cases, the incubation periods vary widely. Because the clinical aspects of STD take so many different forms, no diagnosis can be made just on the appearance of a genital discharge, a small sore or a skin eruption. So it is important not to make a self-diagnosis, nor to apply any cream, lotion or ointment to the genital area, since this can prevent a correct diagnosis being made (for instance, it would make it impossible to detect the presence of treponemes—the micro-organisms causing syphilis—under the micro- scope). And a correct diagnosis is the basis for correct treatment. Nor is it advisable to accept antibiotics recommended by anyone other than a heath professional. If a traveller should detect any suspicious discharge in the course of a journey, and if immediate medical advice is not available, the first step is to cut out all further sexual relations. And on return home, what should the traveller watch out for if he or she has not been over-scrupulous about casual sex? Some discomfort or a burning sensation while urinating; irritation or purulent secretions from the urethra or the vulva; a small lesion or sore on the genital organs, in the mouth or in the anal area; swollen glands that may or may not be painful in the vicinity of the lesion or sore; or a skin eruption anywhere on the body. The traveller should start off by considering any new sexual partner as a potential carrier of a disease. The more partners are involved, the greater the risks. ( Photo WHO/ILO/J. Maillard) "Travel fatigue" For most people, such problems tend to be blamed on travel fatigue, eating too much, or some kind of allergy, and at least half of such cases will be treated with cholagogues (agents that sti- mulate the flow of bile to the duodenum), antihistamines or cor- ticoids (synthetic hormones). And if finally a health professional is consul- ted and the laboratory confirms the presence of a sexually-transmitted dis- ease, most patients express either anger with the partner and a wish for vengeance, or a sense of shame. But what is important is to cease all sex relations at home, and if at all possible to warn the partner who was responsible—who may now be far away. Tracking down previous sex contacts plays a major part in the struggle to control STD, since this is the only way to break up the chain of transmission. If the contact who spread the infection can be reached, every effort should be made to convince that person to be examined and treated. Information about STD contacts is in fact exchanged between many coun- tries, for epidemiological follow-up. And when, after an experience of this nature, our traveller sets off again, can we suppose that a lesson has been learnt? Unfortunately, human nature being what it is, there is a good chance of the traveller succumbing again to temptation and becoming what the unromantic medical statistics call a "recidivist"—one who falls victim for a second or third time to STD—since unlike some other communicable di- seases, one infection does not confer immunity. All the evidence shows that informa- tion about STD is much more convincing, particularly among young- sters, when they are bluntly warned about the possible consequences, namely the risk of sterility in both men and women. It should also be brought home to them again and again that dormant cases of salpingitis in young girls may result in irreversible sterility. An all-out effort is required to overcome the widespread ignorance of STD. The objective should be to ensure that our potential traveller, on the threshold of some exciting new adven- ture, should be both more prudent and better informed when tempted by the siren-song of seduction. ■ 29 In World Cup: These Squads Don't Smoke The Scottish Health Education Group in Edinburgh has laun- ched an anti-smoking campaign centering on Scotland's World Cup team, whose members have publicly declared themselves as a non-smoking team. They take to the field under the slogan "The Squad Don't Smoke". The campaign is aimed at persuading young people— particularly those at the stage of experimenting with cigarettes— that the squad's example is worth following. It is also part of a growing drive to dissociate smoking from sports, and to end the sponsorship of sporting events by tobacco companies. Response has been quick in coming. Referring to the team's action as an "important health educa- tion opportunity" to be seized, WHO's Executive Board has called upon other teams to "em- ulate the Scottish initiative". Already four other teams have done so—Czechoslovakia, Ku- wait, New Zealand and Northern Ireland. "Athletes play exemplary roles, particularly towards the establishment of healthy life- styles in youth", Dr Halfdan Mahler, WHO's Director- General, said in a message to the squad. "The Scottish team de- serves encouragement and best wishes for success." 000 000 000 00* 000 000 000 OOOOOO 000 000 00• 000 000 0 00 00• 000000 ... •oo00• 000 000 000 soo 000 000 *00 000 000 000 000 000 000 000 000 000 00000. 000 000 000 000 . .. ... 000 000 000 000 000 000 000 00• ••• ••• ••• 000 000 000 00• 00• 00• 000 000 000 ... 000 000 000 OOOOO Childbirth Found Easier in Upright Position and With 'Birthing Chair' It is the practice today for women to give birth lying down, delivering their babies while on their backs. Though this position—the "lithotomy position"—is common through- out most of the world, it is in fact relatively new, dating back only about 200 years. Throughout earlier centuries, it was usual for women to sit up for birth, a position still in use today in the world's few remaining primitive societies. The circumstances that led to the change from upright to prone are generally lost in time. How- ever, according to Dr Roberto Calydero-Barcia, director of the Latin American Centre for Peri- natology, in Montevideo, Ur- uguay, for normal births—that is, for those without complica- tions— "birth in the upright position is the natural con- dition". Obstetrical chair developed by the Montevideo centre. Studies carried out in recent years with a "birthing chair", a model of which has been desig- ned by the centre, supports that statement. The chair allows a woman to deliver while seated, thus being placed in a better position, at angles from 45 to 60 degrees, to push down on pelvic muscles. Aimed at determining the eff- ects of a woman's position during delivery on the health of the fetus, the studies—including one com- prising 1,000 births at 11 hos- pitals in seven countries —have shown that labour is easier, shorter, and freer from complications for women using the birthing chair. Developed to promote a more physiologically beneficial way of birth, the chair has also been tested in a study of 19 first-borns, usually the most difficult of births for women. Husbands were not only present during labour and birth but were also taught to give support to their wives, for in- stance by rubbing their backs during labour. "During the first stage of la- bour, mothers preferred to be sitting, standing, or walking, and to move freely, changing from one vertical position to another", a report from the centre says. "During the second stage, all mothers preferred to be sitting on the obstetrical chair designed by the centre." One advantage of the upright position, the study showed, is that less pain-relieving medica- tion, which reduces the supply of oxygen to the fetus, is needed. Women were medicated only when their conditions specifically indicated that this was required to prevent complications of birth, or to correct them, and not as a matter of routine, as is the case in most Latin American hospitals. "The studies suggest that the lithotomy position is not necess- arily the best during delivery", says Dr Sumedha Khanna, chief of community health services at WHO's regional office in Wash- ington, D.C. Though ordinary straight-back chairs could be used, tests of different birthing chairs are con- tinuing. In Fortaleza, Brazil, a simplified version of the model designed by the centre is in use by traditional birth attendants. In the United States, some 400 hos- pitals are using a straight-back chair with a U-shaped seat, acc- ording to the American Founda- tion for Maternal and Child Health, New York. In the Uruguyan study, infants were breast-fed between five to 15 minutes after birth, while mothers were still seated on the birthing chair. Thus, another major advantage of birth in the upright position is that bonding between mother and child takes place virtually immediately after delivery. A New Study Says Cannabis Leads to Dependence One argument advanced above all others in favour of making legal the use of cannabis is that of its relative harmlessness. Now, however, a report of a meeting sponsored by WHO, and the Addiction Research Foundation, a collaborating centre in Toronto, is warning otherwise. The use of "moderate doses of cannabis produces a state of intoxication", the report says. Daily, or more frequent use, can lead to a "chronic intoxication, which may take several weeks to clear after drug use is discon- tinued". In addition, experiences over recent years indicate that can- nabis can be dependence- producing. "There is substantial evidence that at least a mild degree of dependence, psycholo- gical and physical, can occur", the report asserts. Other effects "can range in intensity and character from mild anxiety to acute psychoses". Thus far, only small numbers of heavy users have been studied. Although severe adverse effects, described in clinical reports, oc- cur among them only infrequent- ly, nonetheless "given that mil- lions of individuals are now using the drug, even relatively in- frequent... adverse consequences could be of public health signifi- cance". In industrialized countries sur- veyed, the rates among students who "ever used" cannabis range from less than one per cent, as for Belgium, to more than 60 per cent, as for the United States. Despite the increased use of cannabis since the late 1960s, the report notes that in Mexico, Nor- way, and the United States, there are "recent signs of stabilization" over the past few years. In the developing world, the situation is "much less clear", but the report says that use is "wide- spread in Africa, the Middle East, southern and southeastern Asia, Among effects: From mild anxiety to acute psychoses. Hongkong, and the Philippines, both among lower socio- economic and affluent groups". Overall, the report attributes the lack of studies in the develop- ing countries to an insufficiency of "finances and trained people to carry out the surveys", as well as to the "relatively low priority" given to the health aspects of cannabis use by governments. Not only does the report, which is the work of experts from both developed and developing coun- tries, make the case for more epidemiological studies but also for more research. "Since increasing number of cannabis users are now present- ing signs of dependence, re- search must be conducted on methods of treating this pro- blem", the experts say. But just as important is the need for health education to discourage can- nabis use. The experts met to study the adverse health and behavioural consequences of cannabis use under the chairmanship of Professor Sir William Paton, of 30 WORLD HEALTH 1982 Subscription Rates US$ Sw. fr. One year 15.— 25.- Two years 27.— 45.— Three years 36.— 60.— ORDER FORM Please enter my subscription to "World Health" as follows: One year ❑ Two years ❑ Three years ❑ I enclose cheque/international postal order in the amount of: Name • Street • City: Country: World Health, WHO, Avenue Appia, 1211 Geneva 27, Switzerland. World Health is also distributed through the network of international bookstores and subscription agencies. For payment in national currencies, please contact your usual bookseller. Authors of the Month Dr James HAWORTH was formerly Chief, Publications, with WHO in Geneva and is now retired. Mr J. H.-G. HEMPEL is Technical Officer with the Malaria Action Programme at wHo headquarters in Geneva. Dr Alec SMITH is an entomologist with the Ecology and Control of Vectors unit, WHO'S Division of Vector Biology and Control, Geneva. Dr R. H. HERNIMAN is a Medical Officer with the Diarrhoeal Dis- eases Control programme at wHo headquarters. Professor Arie J. ZUCKERMAN is Professor of Microbiology at the University of London, and Director of the wHo Collaborating Centre for Reference and Research on Viral Hepatitis, London School of Hygiene and Tropical Medicine. Mr John BLAND is the Editor of World Health. Dr P. Bids was Chief of wHo's Virus Diseases unit and is now with the Pasteur Institute in Paris. Dr A. SIBOULET is the Director of the wHo Collaborating Centre for Research in Sexually-Transmitted Diseases at the Alfred Fournier Institute, and Chief Consultant for Urethro-genital Infections at the St. Louis Hospital, Paris. Oxford University. It is their hope that recommendations made will be taken into account by govern- ments in formulating public policy on cannabis. The report, which sells for Canadian $3.25, is published by the Foundation, 33 Russell St., Toronto. Industry Willing to Offer Drugs Under 'Favourable' Terms Over 40 pharmaceutical com- panies have agreed so far to supply drugs to developing countries under "favourable con- ditions", according to Mr S. M. Peretz, vice-president of the International Federation of Pharmaceutical Manufacturers' Association, Zurich. The offer covers the 200 drugs listed by WHO as essential to programmes of primary health care, and which are, a recent WHO report says, "desperately in short supply in almost all de- veloping countries, including those that have the capacity to manufacture them". Exactly just what the con- ditions are, however, have still to be worked out between represen- tatives of WHO and the industry. The problems of quality, price, bulk purchasing, storage and distribution are among the talking points. In a related measure, the ass- ociation also offered to finance three- to six-month courses in drug quality control for 25 trainees from developing coun- tries. So far, six have completed the course, and six more are taking it. Among other indications of industry's response to the need of drugs by developing countries are: A similar training offer by the World Federation of Proprietary Medicine Manufacturers, Federal Republic of Germany. The begin- ning of talks between Interphar- ma, a Swiss group, and Burundi; between Pharmex of Italy and Somalia; and between French pharmaceutical interests and French-speaking countries of Africa, notably Gabon and Senegal. In the next issue The May issue of World Health, which has no single theme, will include articles on family planning, acci- dents, International Youth Year (1985), and further aspects of the 1982 World Health Day theme—Add Life to Years. Newsbriefs Aging. While the population in Latin America is expected to increase by 65 per cent by the year 2000, the 60-plus age group is expected to rise by 82 per cent. The numbers in that age group are projected to be even greater in some countries, doubling in Brazil, Costa Rica, the Dominican Republic, Guatemala, Honduras, and Venezuela, according to the UN Division for Economic and Social Information. As a result of a decline in both birth rates and death rates, Latin America's life expectancy is predicted to rise from 47 years for 1965-70 to 75 years by 2000—almost doubling in 30 years. To cope with such demographic changes the world over, unparalleled in the history of humanity, the United Nations is calling a World Assembly on Aging from 26 July to 6 August in Vienna. And to raise consciousness to the need for a change in attitude towards the aging, WHO has selected "Add Life to Years" as its theme for 1982. Avicenna. A towering figure in medicine and philosophy of the Muslim world, his Canon of Medicine enriched humanity. In five volumes he summed up medical and pharmaceutical knowledge from the Greek and Arab world up to and including his times. On the 1000th anniversary last September of Avicenna's birth—in Bukhara, now in the Soviet Union—Prof. D. V. Subba Reddy, of Osmana Medical College, India, called for new printings of his works, not only in their original Arabic, but also in Urdu and English translations, and—to encourage scholarship—for them to be sold at affordable prices. There is, paradoxically, a scarcity of books on, or about, Avicenna, the Prince of Physicians, who was certainly the most prolific writer of his age. Milestones. This June marks the 10th anniversary of the UN Conference on Human Environment, held in Stockholm in 1972. Regarded as the first, significant UN conference on world issues, it played a large role in making "ecology" not only an international concern, but also a household word, whose cause was espoused particularly by the young. That conference—which produced the Declaration on the Human Environment, and led to the establishment of the UN Environment Programme—is seen as the forerunner to the present UN Water Decade, the goal of which is to provide water supplies and sanitation facilities to all by 1990. Since Stockholm, there have been other similar attempts at consciousness-raising. Among them: the conferences on women, held in Mexico, June 1975; on human settlements, in Vancouver, June 1976; on desertification, in Nairobi, September 1977; on science and technology for development, in Vienna, August 1979; and on the least developed countries, in Paris, September 1981. This year, there's the UN Assembly on Aging (See item above). — This May marks the 60th anniversary of the Boletin, believed to be the oldest, surviving journal on international public health in Spanish. It is published by the Pan American Sanitary Bureau, WHO's regional office for the Americas in Washington, D.C. When its first issue came off the press in 1922, there were just 21 Member States in the Americas, the majority Spanish-speaking. Now membership has grown to 31, with nine English-speaking, whose population totals 610 million. The best of the Boletin is culled for a yearly edition in English. Patenting in the Public Interest. WHO's Executive Board has recommended that WHO patent inventions that derive from programmes, not only to protect them, but also to guarantee that they will be made available widely and inexpensively and that royalties received will be ploughed back into goal-oriented research. The aim is a policy of "health technology in the public interest". Among patent prospects are a fertility regulating device and a vaccine against malaria. People. Appointed to a five-year term as Director of WHO's regional office for the Eastern Mediterranean in Alexandria, Dr Hussein Abdul- Razzaq Gezairy (Saudi Arabia). He leaves his present post, as his country's Minister of Health, to take up new responsibilities, in a region made up of 23 nations, from 1 September 1982. 31 Pilgrims on the move: proper precautions by health authorities ensure that infectious diseases do not spread. ( Photo L. Sirman (D) Be a healthy traveller So you are planning a journey? Fine. But spare a few moments to think about your health—before, during and after your travels. Let us take it for granted that—whether you are going on business, for family reasons or on holiday—you will carry a small first aid kit: antiseptic cream, wound dressings, aspirins, travel sickness pills, sun cream to prevent sunburn (for those with fair skins), insect repellent and an ointment to relieve irritation from insect bites and stings. Depending on where you are going, you may need some other pharmaceutical preparations, but your doctor will advise you on this. Before going As soon as you know where you are going and when, ask your doctor about the possible health risks in the places you are planning to visit, and whether you will need any immunizations. For visits to tropical Africa or parts of South America, yellow fever vaccination is essential if you are going outside the main towns even for a day. This can only be obtained on certain days at special clinics in the bigger cities. Chad still requires a smallpox vaccination certificate although this disease no longer exists in the world. The following countries require a certificate of cholera vaccination in certain circum- stances: Albania, Angola, Brunei, Cape Verde, Chad, Dominican Republic, Egypt, Iran, Lesotho, Libyan Arab Jamahiriya, Mad- agascar, Malawi, Maldives, Mali, Malta, Mozambique, Niger, Pakis- tan, Paraguay, Pitcairn, Republic of Korea, Somalia, Sudan, Swaziland, Tuvalu, United Arab Emirates, Viet Nam and Zambia. However, vaccination does not offer you much protection and should not be regarded as the only precaution you need against this disease. Other immunizations which may be advisable are tetanus and diphtheria which each last about 10 years and typhoid lasting 3 years. Where there is a high risk of poliomyelitis, make sure you are immunized. Most of these protec- tive vaccines are normally given in childhood, but the doctor will assess their present effectiveness. Gammaglobulin can provide some protection for 3 months against the form of jaundice (infectious

hepatitis) to which you are most likely to be exposed. If your children are going to visit a coun- try where tuberculosis is rife, their BCG vaccination status should be checked. If you are going to an area where malaria occurs, your doctor will advise you on which drug to take and how often you should take it. For certain countries you may be advised to carry a few sachets of an oral rehydration mixture to restore your fluid balance if you have diarrhoea, and possibly an antibiotic drug in case you get a severe attack. If you normally have to take certain medicines (after all, chron- ic illness is usually no barrier to travel), make sure you have more than enough of these to cover the time you are away. Pharmacies in other countries may not stock the same preparations. Have you thought that a sudden toothache might spoil your visit? It is worth having a dental check-up before you leave. In case of accidents, you may wish to carry what may be termed a health passport. This records your blood group, any idiosyn- crasy or allergy to drugs, a copy of the optician's prescription of your glasses if you use them, and information about any chronic disease you have and what drugs you use to keep it under control. This is particularly important if you are a diabetic. The travel agent will probably advise you about health insurance—but make sure it is enough. Costs are particularly high in Europe and the USA; for these areas US $ 25,000 should be the minimum coverage for each person. This brochure is intended only as a basic guide, and may assist nation- al health administrations in prepar- ing their own advice to travellers. Such advice should ideally be in a language and format which will have the greatest impact.

Should you be thinking of taking a pet animal with you, make sure you are allowed to: some countries have strict and lengthy quarantine periods, others prohi- bit the importation of any animal, and most require a veterinary clean bill of health and a certificate of anti-rabies vaccination. While travelling Travelling itself involves an abrupt psychological change of life style, and subjects even the most experienced travellers to certain stresses. Many people may find difficulty in sleeping; a few may suffer from seasickness or airsickness. A change of time zone will affect your appetite. You may be inclined to help yourself to too much food and liquid (particularly alcohol); on the other hand, in some cir- cumstances you can easily suffer from dehydration. At stopovers, it is wise in some airports to wear long sleeves and use an insect repellent on the neck and face. If you live in a country with a warm climate and travel to a cold one, remember to have a supply of warm clothes and strong footwear available on arrival. Areas of the world IA here malaria is a risk areas with a limited risk 17 -,-.%3- \reas where malaria transmission occurs At the place of stay If you have been travelling from east to west, you will probably have trouble sleeping at the usual hours; avoid staying up late until your «mental clock» has adjusted, otherwise you will suffer from «jet-lag». If you have gone to a hot and humid area from a cooler or dryer one, you should take care not to overdo exercise at first. Too much sun can be very dangerous; if you have a fair skin, only sunbathe on the first day for 10 to 15 minutes at the most, then gradually increase the exposure until you build up a good tan. The sun is at its strong- est between 10 a.m. and 2 p.m. A change of diet in itself can cause stomach upsets; but in addition, food and drink are the most common sources of germs entering the body and causing food-borne and water-borne diseases. All raw food is a potential source of infection. In places where you have any doubts about cleanliness and kitchen hygiene, avoid vegetable salads and other uncooked vegetables and thin- skinned fruits. Undercooked and raw meat, fish and shellfish may carry various disease organisms. All these foods, if left to cool without refri- geration, may also be dangerous. Better to avoid re-cooked foods. Unless you are very sure about the purity of the water provided, don't use it for drinking and cleaning your teeth unless it has been boiled or treated with water purification tablets. These can be obtained from a chemist before leaving on your trip. Carbonated beverages are safe to drink, but non-gaseous waters (even if bot- tled) and fruit drinks may not be. Milk and its by-products, includ- ing ice-cream, may be risky in some areas. Far away from home, some people may be tempted to embark

- on casual sexual relationships. If so, the use of a condom or diaphragm would be a wise pre- caution, and so would careful washing after intercourse. But there are no prophylactic drugs to prevent all venereal diseases, and their initial signs are very often so slight that they may be over- looked; thus the more dangerous and painful secondary and tertiary forms of certain sexually trans- mitted diseases can develop without previous warning. If you do suspect venereal disease, don't delay before telling your doctor, or have a check-up at one of the special clinics that are found in most cities. In many tropical areas, it is wise to reduce the risk of insect bites by wearing long trousers and long sleeves at night, and better to stay in the hotel area rather than go into the town. In East and West Africa, don't picnic in the shade of trees near ponds or streams; these are favourite places for the tsetse flies that cause sleeping sickness. Avoid petting stray dogs and cats. Rabies is a serious danger in many countries. This is a killer disease which is generally trans- mitted by the bite--or even the lick—of a rabid animal. If you are bitten, even by what looks like a harmless puppy or kitten, wash the area carefully with plenty of soapy water, pour strong alcohol on it, see a doctor and make sure you get a course of anti-rabies serum or vaccine as soon as possible. It could save your life. Be careful where you swim. Avoid muddy ponds, and remem- ber that in some tropical countries, dykes and canals are infested with the freshwater snail, carrier of the parasite which causes schis- tosomiasis (bilharziasis). Sea water bathing too has its hazards—sharks, the jellyfish called Portuguese men-of-war, poisonous fish and sea snakes, or infected cuts from sharp coral. Not every country ensures that its

beaches are free from sewage pollution. Young people par- ticularly like to go barefoot on the sand, or even in the street. But they should be warned about such parasites as hookworm, or insect pests like chigger fleas. Snakes are rarely a danger, since most species slither away when they hear a human approaching. If anyone is bitten, a light tourniquet should be immediately applied to the affected limb (but only for a short period of time) and medical attention should be urgently sought so that anti-venom can be given if needed. Scorpion and spider stings can be extremely painful and some are quite dan- gerous too. Remember to shake out your clothes and shoes in the morning before dressing. On your return Remember to go on taking the anti-malarial pills for at least a month. The most dangerous form of malaria usually causes severe illness within two weeks, but other forms may not affect a person for weeks or even months. Similarly, sleeping sickness may take several months to become obvious, and other diseases may not develop for as long as a year after the return home. One form of jaundice (infec- tious hepatitis) may take up to two months to appear, and rabies up to one year if no post-bite immuniza- tion has been given. Anthrax, which causes a dangerous boil and is acquired from handling infected untanned leather goods, appears after several days. Syph- ilis may not become apparent for three months. Be sure to tell your doctor about any international journeys you have made during the previous 12 months if you have to see him for any sickness after your return. The simple precautions outlined here should enable you to plan your trip, to travel, and to return home—without undue anxiety about endangering your health. Be prepared before you travel. Find out what health risks may exist in the coun- tries you will visit, and what precau- tions you can take. Be a healthy traveller. Division of Public Information, WHO 1211 Geneva 27, Switzerland WORLD HEALTH ORGANIZATION