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United States Department of Agriculture

Agricultural Research Service

Project Type: Appropriated

Start Date: Dec 20, 2005
End Date: Dec 19, 2010

The objectives are to improve food safety and reduce contamination of drinking water by improving detection, determining sources, and reducing transmission of protozoan parasites infecting humans. Objective 1 a) Improve speed and accuracy of methods to detect Cryptosporidium, Giardia, and Microsporidia in selected environmental specimens and in specimens from food animals, other farm animals, wildlife, and transport hosts that might harbor multiple species or genotypes. b) Develop monoclonal antibodies specifically to identify zoonotic species of Cryptosporidium. Objective 2 a) Determine the prevalence of Blastocystis spp. in 1000 pre- and post-weaned dairy cattle from farms in eastern states utilizing DNA from our immediate past project; determine the prevalence of Microsporidia, Blastocystis, Giardia, and Cryptosporidium in 150 sheep and 500 pigs from birth to market age from multiple farms and states, and from 1000 feedlot beef cattle in Nebraska. b) Determine the presence of these same organisms in environmental specimens provided by NOAA collaborators from waters impacted by agricultural runoff. c) Assess the potential infectivity, duration of infection, and numbers of parasites excreted throughout a period of infection, by experimentally infecting parasite-free cattle, sheep, pigs, chickens, turkeys, and laboratory rodents with any unique genetic isolates found in the field studies described above. Objective 3 a) Test for protective immunity of HBC fed to neonatal calves experimentally challenged with C. parvum oocysts by observing the severity and duration of infection. b) Conduct biochemical and molecular studies that might serve as a basis for future treatment strategies to interfere with transmission of parasites. c) Test anti-viral drugs associated with reduction of cryptosporidiosis in AIDS patients and in vitro will be tested for efficacy against zoonotic Giardia and Cryptosporidium, both of which have been shown to contain RNA viruses.

Studies will identify Giardia, Cryptosporidium, and Microsporidia of livestock and wildlife by developing multiplex PCR techniques and examining new gene sequences to provide improved characterization of these organisms. Viruses have been found within Giardia and Cryptosporidium, and studies will determine if differences in the quality or quantity of such viruses using newly developed reagents can facilitate detection and differentiate pathogenic and non-pathogenic strains. The prevalence of Giardia, Cryptosporidium, Microsporidia, and Blastocystis in sheep and pigs, and feedlot cattle will be determined. The prevalence of Blastocystis also will be determined in dairy cattle. Unique genotypes of these pathogens from field isolates will be tested in transmission studies to determine their potential to infect other animal hosts. The presence of zoonotic protozoan pathogens in environmental specimens in areas impacted by runoff from agricultural animals will be assessed. Studies will identify methods to provide protective immunity against Cryptosporidium. Cows will be immunized with recombinant proteins and immune stimulators to produce colostrum with high levels of anti-Cryptosporidium antibody for passive immunization of calves. Biochemical and molecular techniques will be used to study encystation/excystation in Giardia and Cryptosporidium to identify proteins that can be targeted to disrupt transmission. Anti-viral and anti-protozoal drugs will be tested against Cryptosporidium and Giardia using cell culture and animal infectivity models.

Last Modified: 4/18/2014
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