Atlas of foodborne infections
transmitted by contaminated food and water

Atlas of Patogens Contents Information sources Glossary Administration

Food-borne parasitic diseases

CZ: parazitózy
EN: parasitosis

Meat and Meat Products
Fish and Fish Products
Fruits and Vegetables
Water and Beverages


Foodborne Disease:
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Food-borne parasitic diseases are a major public health problem affecting millions of people, predominantly in nonindustrialized countries.

The incidence of parasitic disease associated with the consumption of foods of animal origin has declined in industrialized countries in recent years, where improvements in animal husbandry and meat inspection have led to considerable safety and quality gains.

The situation in nonindustrialized countries is very different, in that these diseases are associated with poor standards of sanitation and hygiene, low educational standards and extreme poverty.

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Parasites are organisms that live off other living organisms, known as hosts. They may be transmitted from animals to humans, from humans to humans, or from humans to animals.

Food-borne parasitic disease occurs when the infective stages of parasites are eaten in raw or partially cooked protein foods, or in raw vegetables and fruits that are inadequately washed before consumption. These organisms then live and reproduce within the tissues and organs of infected human and animal hosts, and are often excreted in feces.

The parasites involved in food-borne disease usually have complex life cycles involving one or two intermediate hosts. The food-borne parasites known to cause disease in humans are broadly classified as helminths (multicellular worms) and protozoa (single- celled microscopic organisms).

These include the major helminthic groups of trematodes, nematodes and cestodes, and some of the emerging protozoan pathogens, such as Cryptosporidia and Cyclospora. The illnesses they can cause range from mild discomfort to debilitating illness and possibly death.

These infections occur endemically in some 20 countries, where it is estimated that over 40 million people worldwide, mainly in eastern and southern Asia, are affected.

Of major concern are the fish-borne trematode infections. The trematode species concerned all have similar life cycles involving two intermediate hosts. The definitive host is man and other mammals. Food-borne infection takes place through the consumption of raw, undercooked or otherwise underprocessed freshwater fish or crustaceans containing the infective stages (meta- cercariae) of these parasites.  Distribution, the principal reservoirs and freshwater fish or crustaceans involved in the transmission of these parasites in the food chain, all is described in this atlas according genuses of parasites.

The most important parasites with respect to the numbers of people affected are species of the genera Clonorchis, Opisthorchis and Paragonimus. The diseases caused by food-borne trema- todes include cholangiocarcinoma, gallstones, severe liver disease and gastrointestinal problems.



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