Crytposporidiosis. Importance of water as a source of infection

Abstract

Described in 1907, Cryptosporidium, a protozoan parasite, was considered as a rare, commensal and specific organism. After 1981, C. parvum was recognized as a common source of contamination in all mammals including humans. Symptoms are neonatal diarrhea in ruminants and self limiting or life threatening diarrhea in immunocompetent or immunodeficient hosts, respectively. The first reports indicated that infected animals were the source of human infections and that cryptosporidiosis was a zoonotic disease. Nevertheless, cryptosporidiosis may be transmitted directly from person to person and indirectly by water. Pollution of all types of surface water, lakes, reservoirs, rivers etc can result from agriculture but sewage from infected populations are also a source of contamination. The sewage treatment processes, filtration and desinfection, are not fully effective and oocysts have been found in drinking water in North America and the United Kingdom. From 1985, studies have been carried out to enumerate, identify and inactivate Cryptosporidium oocysts in water.