Foodborne illness : a growing problem / by Mohammed Abdussalam and Dieter Grossklaus

T housands of cases of cholera in Latin Amer-ica have focused public attention on the menace of contami- nated food and water. Individual cases or small outbreaks of foodborne disease generally remain unnoticed or may not be reported by physicians. Perhaps less than 10% of cases of foodborne illness are reported in the official morbidity statistics of industria- lized countries, while in developing countries the corresponding figure may be as low as 1%. Furthermore, it has been observed that these diseases continue to increase both in the developed and developing countries. The reasons for this increase are not fully understood, but it is believed that insufficient attention to foodborne disease is paid by health authorities in many parts of the world. Such disease is caused by contami- nants acquired during the production, storage and distribution of food. Some may be eliminated during processing, whereas the others may survive and may increase under certain conditions. The nature and incidence of food- borne illness is strongly influenced by agricultural practices, food technology in industry and the home, and ecologi- cal, environmental, socioeconomic and cultural factors. Other factors such as beliefs about health and disease, relig- ious convictions and even considera- tions of prestige influence the selection, preparation and consump- tion of food. The resulting eating habits may sometimes protect people against disease, but often they lead to illness, for example through the con- sumption of raw or undercooked food. Prejudice against the irradiation of food, a technology that can assure safety at reasonable cost, is widespread even among educated people. Eating habits and their underlying beliefs are very difficult to change and they present a considerable challenge to health educators. Contaminants Microbiological contaminants are responsible for over 90% of episodes of foodbome illness, including typhoid fever , non-typhoid salmonelloses, cholera, other diarrhoea) diseases, bacterial and amoebic dysenteries, botulism and other bacterial intoxi- cations, hepatitis A, and trichinellosis. In industrialized countries many of these diseases have declined in recent decades, but salmonellosis and some others have defied all efforts to control them. In Germany the incidence of 18 Foodborne illness: a growing problem by Mohammed Abdussalam and Dieter Grossklaus these diseases may have risen as much as ten- or twentyfold in the last two decades. Similar trends have been reported in Canada, Finland, the United Kingdom, the USA and else- where. In 1985 it was estimated that there were at least 24 million cases of diarrhoea caused by foodbome micro- organisms annually in the USA The associated costs were considered to be up to US$ 10 000 million a year. It was recently estimated that in the Netherlands there were annually 1.5 million cases of foodborne microbial diseases in a population of 15 million. The information available from developing countries shows that these diseases are common there also, as exemplified by infant diarrhoea. This is to be expected, since sanitation can be poor and water supplies are often polluted. In fact the problem is more serious because of widespread malnu- trition and the threat of cholera, typhoid and several parasitic diseases. The medical, social and economic burden of these mainly foodborne diseases is certainly heavier in the developing countries than in the developed world. Chemical contaminants include pes- ticides and drugs used in agriculture, residues of which may persist in food. Other substances may come from the wider environment. None of the chemicals used in food production is known to constitute an appreciable health hazard if the recommendations of the FAO/ WHO Codex Alimentarius Commission are followed and as a result the quantity of the residue does not exceed the prescribed limits. In industrialized countries, where appro- priate control measures are taken, illness caused by chemical contami- nants of food is minimal. However, these contaminants are viewed with considerable misgivings by many members of the public. The illegal use of chemicals in agriculture or as food additives can have serious conse- quences, as with the fraudulent addi- tion of motor oil to edible oil and the milling of mercury-treated wheat. Dur- ing 1981-82 in Spain, over 500 people died and many were crippled as a result, apparently, of consuming adulterated olive oil. However, apart from their illegal use, chemicals consti- tute a much smaller hazard as food contaminants than do microorganisms and parasites. Toxic plants constitute a problem in some regions. In others the poorer sections of the population may con- sume potentially toxic grains, e.g. Jathy- rus or cereals carrying ergot. Many moulds on grains, fruit and oilseeds produce mycotoxins, some of which have been shown to cause liver cancer in animals. Marine fish and shellfish sometimes become dangerously toxic without warning. Ciguatera poisoning in the Atlantic and puffer fish poisoning in the Pacific are well-known fishbome intoxications. Paralytic shellfish poison- ing sometimes occurs following the consumption of shellfish harvested on sea coasts, even in temperate regions. This type of poisoning is to be distin- guished from illness caused by infec- tious agents such as those responsible for typhoid, cholera and poliomyelitis, which can also be transmitted by shellfish. What makes contaminants dange10us For a contaminant to produce disease it has to be sufficiently toxic or virulent and present in adequate quan- tity when the affected food is con- sumed by a susceptible person. Several A milk-bottling plant in Nepal. Strict control of industrial food processing assures the safety of the final product. chemicals and many biotoxins survive cooking and other procedures employed in the preparation of foods. Much more important, however, is the growth of disease-producing bacteria in food. They are responsible for most outbreaks of foodborne ill- ness. Ordinarily, small numbers of these bacteria, after being swallowed with food, are killed by the acidic juices of the stomach or are made harmless by the immune mechanism in the body, and no illness results. If they are swallowed in large numbers, on the other hand, severe disease may be produced. If certain nutrients and water are present in food stored at room temperature for more than 4-5 hours, bacteria may multiply and disease may occur. Bacterial growth is inhibited by cold storage, acidity and certain quantities of salt or sugar that interfere with the availability of water. Food containing large numbers of bacteria may nevertheless be rendered safe by adequate heating, although this does not remove bacterial toxins. Conditions favouring bacterial growth and the formation of toxins arise largely because of the ways in which food is handled, processed, stored and consumed. Outbreaks of foodborne disease in industrialized countries have been linked with the preparation of food too far in advance and its storage at room temperature, inadequate cooking or reheating, the use of contaminated ingredients and unsafe water, and cross-contamination between raw and prepared food. Strategies for safety Food safety in most countries typically depends on the enforcement of laws and standards through systems of inspection, and on some education of food handlers. Unfortunately, even the well-developed health infrastruc- tures and sophisticat€id technologies in industrialized counfries have not resulted in satisfactory control of food- borne diseases. In developing coun- tries, where health infrastructures can be weak, street vending of food is common and rural food supplies may not go through a marketing system, the legal approach adopted in industrialized countries is only partly applicable. The improvement of food safety everywhere requires the primary health care approach to be adopted in addi- tion to legal control and inspection. Bearing in mind the socio-cultural values of the community, messages on food safety have to be disseminated as widely as possible. The Food and Agriculture Organi- WORLD HEALTH, July-August 1991 Preparing a meal in Venezuela. Dishes cooked fresh and served immediately help to reduce the risk of foodbome diseases. zation and WHO have been working for the last three decades on the legal, administrative, technical and commer- cial aspects of food control in their Food Standards Programme. In addi- tion, WHO is helping to incorporate food safety into primary health care systems. A rapid and inexpensive approach to the identification of faulty food handling has been developed. It has been tried in low-income homes and in food service establishments in both industrialized and non-industria- lized countries. The information gathered and the related epidemiologi- cal investigations provide a sound basis for health education aimed at correc- ting faulty practices. WHO has put forward ten golden rules for safe food preparation in homes and restaurants ( World Health, November 1988, page 7). It is also worth noting that in many industrialized countries special atten- tion is being paid to the rearing of farm animals free of infectious agents. All such measures require the close collaboration of communities, industry, and government agencies concerned with health, agriculture, veterinary care, commerce and education. • Professor Mohammed Abdussalam is a former staff member of WHO. Professor Dieter mGross- klaus is President of the Bun des g e sun d he i ts a rr1 t. Postfach 33 00 13. D-1 000 Be,rlin 33:·, Germant . .. f he way we eat has a direct influence on the development of certain types of cancer. In t'he industrialized world, where the rates are highest and where cancer is responsible for about one quarter• of all deaths, some studies have blamed dietary factors for 30-40% of cancer caseS"' in men and for as much as 60% in women. What is dangerous, and what isn't? The regular consumption of large quanti- ties of alcohol is implicated in such cancers as those of the mouth, pharynx, oesoph- agus and upper larynx, as well as the liver. Women who are overweight as a result of enjoying an over-rich diet risk getting cancer of the. endometrium {the mucous membrane of the uterus), or breast cancer after the menopause. Stomach cancer has been linked to foods that have been smoked or preserved in salt. which may lead to the long-term formation of nitrosamines, chemical substances that increase the. risk for cancer. They act together with an insufficient consumption of fruits and fresh vegetables, which slow down the formation of nitrosamines. In places where methods of keeping food fresh have greatly improved, particularly by refrigeration, we have seen a considerable decline in stomach cancer over the last 50 years. But it would be wrong· to cut out certain foods on the grounds that they might be carcinogens. What really matters is a balanced diet. As epidemiological studies seem to show-and this is confirmed by experi- ments with "animals-a high consumption of fats, particularly the saturated fats of animal origin, increases the risk of cancer of, the large bowel, prostate, and breast. Breast cancer offers an interesting example. lt is very frequent in the USA and qllite rare in Japan, so ·doctors thought at . first it might be of genetic origin. But it was 'l,nfound t~at th~ mortality rate from breast ''~" cancer m Japanese women who had "migrated to the USA was just the same as among American women. This type of cancer has been linked to life-styles and very probably to a diet high in fats, as is the case in the adoptive countries of immi- grants. But this factor acts in association with others, such as a high calorie intake and obesity. Certain factors that are linked to life- style, such as deferring childbearing to a much later age or not having a child at all, increase the risks of breast cancer. Elements that protect us Our present knowledge does not yet allow us to say precisely how big a role the dietary factors play in the appearance of cancer, but we don know that modifying certain dietary ha!:>its can reduce the risks. Everything leads us to believe that a diet that is low in fats (particularly saturated fats) alcohol, smoked foods and foods preserved in salt or vinegar, but is rich in vegetable foods, especially green and yellow vegetables and fruit, including citrus fruits, can help to lower considerably the risk of several major types of cancer that occur today, particularly cancers of the large bowel, prostate, stomach, lungs, and oesophagus. C.V.