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United States Department of Agriculture

Agricultural Research Service

Research Project: PROTOZOAN PARASITES AFFECTING FOOD ANIMALS, FOOD SAFETY, AND PUBLIC HEALTH Title: Foodborne Protozoans

Authors
item Dixon, Brent -
item Fayer, Ronald
item Santin-Duran, Monica
item Hill, Dolores
item Dubey, Jitender

Submitted to: Rapid Detection, Characterization, and Enumeration of Food-Borne Pathogens
Publication Type: Book / Chapter
Publication Acceptance Date: March 25, 2011
Publication Date: May 4, 2011
Citation: Dixon, B., Fayer, R., Santin, M., Hill, D.E., Dubey, J.P. 2011. Protozoan parisites: Cryptosporidium, Giardia, Cyclospora, and Toxoplasma. In: Hoorfar, J., editor. Foodborne Protozoans. Rapid Detection, Characterization, and Enumeration of Food-Borne Pathogens. Washington, D.C.: American Society for Microbiology. p. 349-370.

Interpretive Summary: Identification of the human pathogens Cryptosporidium and Giardia can be made with the aid of a microscope, using specialized adaptations called phase contrast, differential interference contrast or fluorescence microscopy. With requirements for ever increasing sensitivity and specificity the trend is to rely less on microscopic observations and more on DNA fingerprinting methods. Most Cryptosporidium and Giardia infections are spread by contaminated recreational and drinking water. Therefore, efforts to prevent contamination need to focus on reducing fecal contamination from persons with diarrhea or known infections from entering recreational waters and for backpackers or campers from drinking water directly from rivers, streams or ponds. Filtering or boiling water can remove infectious cysts. Because most foodborne infections with Cryptosporidium and Giardia have been traced to foodhandlers with diarrhea, or in association with children with diarrhea, they should not be handling food served to the public or their family members. Because this action would be difficult or impossible to enforce, all foodhandlers should wear clean disposable gloves when handling foods. A general approach for prevention of foodborne disease is to wash, peel, or cook raw fruits and vegetables before eating.

Technical Abstract: Identification of the human pathogens Cryptosporidium and Giardia can be grouped into general morphology by microscopy, chemical and immunofluorescent staining methods aiding microscopy, and biochemical and molecular tests. Microscopic observations can be made using brightfield with or without special stains, phase contrast, differential interference contrast or fluorescence microscopy. With requirements for ever increasing sensitivity and specificity the trend is to rely less on microscopic observation and more on instrumentation. Most Cryptosporidium and Giardia infections are spread by contaminated recreational and drinking water. Therefore, efforts to prevent contamination need to focus on reducing fecal contamination from persons with diarrhea or known infections from entering recreational waters and for backpackers or campers from drinking water directly from rivers, streams or ponds. Filtering or boiling water can remove infectious cysts. Because most foodborne infections with Cryptosporidium and Giardia have been traced to foodhandlers with diarrhea, or in association with children with diarrhea, they should not be handling food served to the public or their family members. Because this action would be difficult or impossible to enforce, all foodhandlers should wear clean disposable gloves when handling foods. A general approach for prevention of foodborne disease is to wash, peel, or cook raw fruits and vegetables before eating.

Last Modified: 10/22/2014
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