Travellers, beware! / by Penelope Phillips-Howard

Travellers, beware! by Penelope Phillips-Howard hether they are on business, on holiday or visiting relatives, international travellers are at risk of catching malaria when they visit an endemic area. Other groups, such as itinerant workers and refugees who come from non- malarious areas and who are compelled to move to a place where the disease is common, are also greatly at risk, requiring close attention from the host governments or agencies. Every year non-malarious countries of Europe, North America, the Far East and many other countries in the southern hemisphere report cases of "imported" malaria in travellers who have returned from malarious areas. The number of cases of imported malaria reported to WHO has doubled over the past decade, largely as a result of mass tourism to tropical locations. At present, some 10 000 cases are 24 reported in Europe and over 1000 in North America every year. Not all travellers visiting malarious countries are automatically at risk of contracting malaria; for example, travellers visiting major cities in South- East Asia such as Bangkok or Singa- pore will generally not be exposed to malaria transmission. The highest risk of contracting the most dangerous species of malaria, Plasmodium falciparum, occurs in travellers visiting malarious areas in Africa, south of the Sahara. As many as one in every hundred visitors to countries of West Africa, such as Nigeria and Ghana, become infected and have symptoms of the disease on return to their home country. The activities and behaviour of indi- viduals influence their risk of becoming infected, which depends on their Tourists need to be aware that danger may lurk even in a tropical paradise_ Golden Rules for Travellers If you intend to travel to areas where there may be a risk of malaria: 1. Contact your physician or an institution which can be trusted to give competent advice, e.g., a vaccination centre. Request advice on whether there is any malaria risk where you are going; if there is, ask which antimalarial drug to take for prevention, how to take it, and what side- effects it may have. 2. Take the drug in the exact dosage prescribed and continue for four weeks after leaving the mala- rious area. 3. In malarious areas, take sensible precautions. Sleep in screened rooms or under bednets, prefera- bly impregnated with insecticide; from dusk to dawn wear clothes that cover arms and legs; cover unprotected skin with an insect repellent. 4. Be aware of the symp- toms of malaria infection. If you have an unexplained fever, headache, muscular aching, vomiting or diar- rhoea on returning from a malarious area, seek medical advice at once and tell the physician where you have been. Malaria can manifest itself up to a year after depar- ture from a malarious area, even if antimalarial drugs have been used. 5. Remember that malaria can rapidly become severe and may cause death less that 48 hours after the first symptoms have appeared. 6. For pregnant women, small children, and per- sons with chronic liver, kidney or heart disorders, it should be considered whether the journey is really necessary; consult a physician. W OR LD HEALTH . September-October 1991 ~ different degrees of exposure to mos- ~ quito bites and their varying abilities to ] seek and use methods of prevention. c. Malaria occurs much more frequently in migrant populations who travel to their former homeland to visit family and friends than in other travellers going on business or vacation. This is because they often do not receive information about the risk of malaria and they stay in areas where malaria transmission may be higher than in business or tourist locations. Misunderstandings about what causes malaria and how it can be prevented are common among travellers; in one survey of European travellers, only 30% knew that malaria was transmitted by mosquitos biting between dusk and dawn. Some partici- pants who were questioned even thought that malaria was transmitted from drinking contaminated water! The presence of parasite resistance to antimalarial drugs also plays a major role in the risk of malaria disease and death. Travellers may not be aware that their antimalarial drugs taken for preventive purposes are not one hun- dred percent effective and may there- fore fail to seek medical help if malaria symptoms develop. If deaths from malaria are to be prevented, physicians must understand how important it is to start treatment with effective antimala- rial drugs very early in the course of disease in order to prevent the devel- opment of life-threatening compli- cations. A number of "golden rules" are recommended by WHO and national authorities regarding malaria preven- tion (see box on page 24). Both travellers and their physicians should be aware that visits to malarious coun- tries may result in infection which, if not properly recognized, can result in disease and death. A tragic example of what can happen occurred recently when a married couple returned to Europe from Uganda. When the flight arrived, the wife was immediately admitted to hospital with P falciparum malaria. The husband also felt unwell but returned to their home. One week later, the wife was discharged from hospital only to find her husband dead at home; he too had contracted malaria but was unable to seek medical help. All cases of febrile disease in persons who have recently visited malarious areas should be examined by micro- scopy of the blood for the presence of malaria parasites. If a first examination is negative, it should be repeated several times. Certain population groups are WORLD HEALTH .' September-October 1991 strongly advised not to visit a mala- rious country unless they really have to; they include young children, preg- nant women, the elderly, and people with chronic diseases such as liver, kidney and heart disorders. Planning to go abroad? Whether crossing continents or just the nearest border. interna- tional travel can be a great way to broaden your horizons. lt can also introduce you to some rather nasty local microbes. like all those viruses. bacteria. protozoa. and other exotic bugs that love to prey on strangers. Masters of · disguise. local infectious agents can get you via a sip of water or a bite of salad. a shower: a sting. ice cream. shellfish. or simply the air you breathe. Every year. the hazards of going abroad make travellers the victims of some very serious diseases. Which is why the World Health Organization issues a book on vaccination requirements and health advice for international travel every year. Designed to safeguard the health of travellers. the book alerts health authorities to changing immunization requirements and other measures of protection against the hazards of going abroad. including con- siderable information on the malaria risk. The book will give your doctor or travel agent a good idea of this and other risks that may be waiting in the intended country of travel. And will help them advise what you must do to protect yourself and your health . Be advised before you go International travel and health Vaccination requirements and health advice. situation as on 1 January 1991, 94 pages. Sw.fr. 14.- Available from WHO. Distributi on and Sales. 1211 Geneva 27. Switzerland. Wherever malaria occurs, travellers should protect themselves against biting mosquitos through the use of bednets , repellants and similar measures. Antimalarial drugs need to be taken with unfailing regularity. However, travellers should be made aware that no drug gives one hundred per cent protection against infection and that malaria should be suspected if a fever develops, even when drugs have been taken exactly as prescribed. Cutting down on the dosage because of fear of overdose, loss of tablets, mild side- effects such as nausea, or belief that immunity has been achieved, all lead to an increased risk of infection. Conti- nuing medication after returning home is always a problem, since there appears to be no further risk from biting mosquitos. But malaria parasites may still be present in the blood, and medication is important for four weeks after leaving the malarious area. Unusual outbreaks of malaria may sometimes occur in non-endemic countries. In recent years there have been several instances of malaria trans- mission around international airports in non-endemic countries. Very rarely, malaria has been transmitted by conta- minated needles, e.g., in drug addicts. The risk of getting malaria through blood transfusion is considerably greater (parasites may be present in the blood of apparently healthy donors). In some non-malarious coun- tries, blood donations are therefore not accepted from persons who have visited malarious countries. Greater awareness of the dangers of malaria for travellers is needed at all levels of the travel market. Tourism organizations, airlines, business consor- tiums and other such institutions must recognize the hazards associated with international travel and their responsi- bility to minimize the risk of illness and death from malaria in their clients and personnel. At national and interna- tional levels, improvements are required in guidelines to ensure that travellers to malarious countries receive adequate protection against malaria infection, that their symptoms of malarial disease are recognized and diagnosed promptly, and that appro- priate medical steps are taken. • Dr Penelope Phillips- Howard is a Scientist with the Malaria Control Unit. WHO. 1211 Geneva 27. Switzerland. 25