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United States Department of Agriculture

Agricultural Research Service

Title: A Synopsis of Cryptosporidium Research in Shellfish

Authors
item Fayer, Ronald
item Lewis, E. - NOAA

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: July 24, 2001
Publication Date: July 24, 2001
Citation: Fayer, R., Lewis, E.J. 2001. [Meeting Abstract]. A synopsis of Cryptosporidium Research in Shellfish.

Technical Abstract: Cryptosporidium spp., Giardia duodenalis, and Microsporidia are protozoan parasites that cause disease in humans, livestock, wild and companion animals. The source of these pathogens is human and animal feces. The diseases, cryptosporidiosis, giardiasis and microsporidiosis are transmitted by contaminated water, food, and close contact with infected individuals. All of the above organisms have been found in surface waters in the U.S. Of ten species of Cryptosporidium, only C. parvum is infectious to immune competent people. Cryptosporidiosis is recognized as an emerging health issue worldwide, with cases reported from 95 countries. It is a potential environmental and public health issue that requires further investigation. Until specific sources of these pathogens have been identified, rational plans cannot be developed to reduce or prevent contamination of surface waters and potential risks related to use of waters for recreation, drinking, or harvesting of shellfish to be consumed raw. In our field studies, a high prevalence of positive oysters was found at 6 selected sites. Then, 7 commercially harvested oyster bars were also investigated. Data revealed oysters and water samples from all 13 sites were positive for C. parvum every time they were examined over the following three years although the number of oysters harboring oocysts varied from many to few at different collection times. Using molecular techniques some oocysts recovered from oysters were of the human genotype (transmissible from human to humans). Others were a variety thought to infect over 150 species of mammals including humans. Still others were from chickens and reptiles. Oocysts in recovered oyster tissues on several occasions were found infectious for laboratory mice.

Last Modified: 9/10/2014
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