Last update:
06-Jul-2004

Water, soil and food constitute significant environmental routes of transmission for many protozoan and helminth parasites. Parasites possess the potential for producing large numbers of transmissive stages with profound environmental sturdiness, able to survive in moist microclimates for prolonged periods of time; thus they pose an unrelenting public and veterinary health threat. The likelihood of encountering environments and produce contaminated with parasites correlates with the increased demands on natural resources. The protozoa Cryptosporidium, Giardia and Toxoplasma are the most significant causes of waterborne diseases. In the case of cryptosporidiasis and giardiasis, due to the absence of “standardised” methods, the contribution of zoonotic transmission remains blurred. The role of animals as the cause of microsporidian contamination in one waterborne outbreak has not been elucidated. In foodborne parasite zoonoses, the fecal-oral pathogens are involved with surface contamination, and data available indicate that animal wastes (e.g. cattle feces) remain an important source of contamination. However, further work should focus on examining the contamination of fruit and vegetables. Human fascioliasis is now recognised as an emerging zoonosis by the WHO. The most important meatborne parasites are Toxoplasma, Trichinella and Taenia spp and others, including Pleistophora-like microsporidians, may be acquired from raw or lightly cooked fish or crustaceans. The public health importance of the foodborne trematodiases correlates well with increased international travel. Shifting consumer vogues, including the consumption of raw vegetables and undercooking to retain the natural taste and preserve heatlabile nutrients, in combination with the global sourcing of food, increase the risk of foodborne transmission. A greater awareness of the parasite contamination of the environment and its impact on health has precipitated the development of better detection methods. Efficient detection, viability and subtyping methods are required to assess the risks and to further epidemiological understanding.

Key words: Εnvironmental routes of transmission, Parasitic zoonoses, Public health.