WHY DO FOODBORNE DISEASES EMERGE?
New foodborne disease threats occur for a number of reasons. These include increase in 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 cyclosporiasis occurred in North
America in 1996-7 linked to contaminated
raspberries imported from South America.
The inadvertant introduction of pathogens into
new geographic areas: Vibrio cholerae was
introduced into waters off the coast of southern
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 South
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
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.
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
5 Keys to Safer Food and a guide on Safe Food for
Travellers.
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