Cover Image
close this bookFact sheet No 124: Emerging Foodborne Diseases - Revised November 1996 (WHO, 1996, 3 p.)
View the document(introduction...)
View the documentBackground
View the documentWhy Do Foodborne Diseases Emerge?

Why Do Foodborne Diseases Emerge?

New foodborne disease threats occur for a number of reasons. These include international travel and trade, microbial adaptation and changes in the food production system, as well as human demographics and behaviour.

# The globalization of the food supply. A large outbreak of Shigella sonnei infections occurred in Great Britain, Norway, and Sweden in 1994 due to contaminated lettuce imported from southern Europe.

# The inadvertant introduction of pathogens into new geographic areas. Vibrio cholerae was introduced into waters off the coast of southern United States when a cargo ship discharged contaminated ballast water in 1991. It is likely that a similar mechanism led to the introduction of cholera for the first time this century into Latin America in 1991.

# Travellers, refugees, and immigrants exposed to unfamiliar foodborne hazards while abroad. International travellers may become infected by foodborne pathogens that are uncommon in their countries. It is estimated that about 90% of all cases of salmonellosis in Sweden are imported.

# Changes in microorganisms. Changes in microbial populations can lead to the evolution of new pathogens, development of new virulent strains in old pathogens, development of antibiotic resistance that might make a disease more difficult to treat, or to changes in the ability to survive in adverse environmental conditions.

# Change in the human population. The population of highly susceptible persons is expanding world-wide because of ageing, malnutrition, HIV infections and other underlying medical conditions. Age is an important factor in susceptibility to foodborne infections because those at the extremes of age have either not developed or have partially lost protection from infection. Particularly for the elderly, foodborne infections are likely to invade their blood stream and lead to severe illness with high mortality rates. People with a weakened immune system also become infected with foodborne pathogens at lower doses which may not produce an adverse reaction in healthier persons. Seriously ill persons, suffering, for example, from cancer or AIDS, are more likely to succumb to infections with Salmonella, Campylobacter, Listeria, Toxoplasma, Cryptosporidium, and other foodborne pathogens. In developing countries reduced immunity due to poor nutritional status render people, particularly infants and children, more susceptible to foodborne infections.

# Changes in lifestyle. Greater numbers of people go out and eat meals prepared in restaurants, canteens, fast food outlets, and by street food vendors. In many countries, the boom in food service establishments is not matched by effective food safety education and control. Unhygienic preparation of food provides ample opportunities for contamination, growth, or survival of foodborne pathogens.

All food-borne diseases pose a considerable threat to human health and the economy of individuals, families and nations. Their control requires a concerted effort on the part of the three principal partners, namely governments, the food industry and consumers. As part of its food safety education campaign, WHO issued the 10 Golden Rules for Safe Food Preparation and a guide on Safe Food for Travellers.