CRYPTOSPORIDIUM PARVUM

A parasite often found in the intestines of livestock which contaminates water when the animal feces interact with a water source. Literally, cryptosporidium means "mystery spore," and the parasite was not recognized as a human pathogen until 1976. In healthy individuals, infection may result in an acute diarrheal illness lasting for 2-3 weeks. In immuno-suppressed individuals (e.g., AIDs patients, children, elderly), Cryptosporidiosis, the disease from infection by the parasite, may be life-threatening. While much needs to be learned about the infectious level of crypto, studies have indicated that it takes five to ten cysts to make someone sick. Of particular concern to health officials and public drinking water supplies is that the most widely used agent to disinfect tap water: chlorine: does not kill the parasite. Also, the laboratory tests used to detect crypto are time-consuming, laborious, and expensive. As an additional complication in the detection process, there are several varieties of crypto, but only one: Cryptosporidium parvum: is infectious to humans. Also, laboratory tests cannot determine whether a Crypto Oocyst, the hard shell that protects the protozoa, is alive or dead. Currently, the only effective treatment for water supplies is through filtration (crypto oocysts are only 3 to 7 microns in size) and the use of ozone gas rather than chlorine. As of January 1997, the U.S. Environmental Protection Agency (EPA), through the Information Collection Rule (ICR), has required that all public water supply systems serving more than 100,000 connections to monitor for cryptosporidium.