Grantee Research Project Results
2000 Progress Report: Prevalence and Distribution of Genotypes of Cryptosporidium Parvum in Feedlots in the Western United States
EPA Grant Number: R828038Title: Prevalence and Distribution of Genotypes of Cryptosporidium Parvum in Feedlots in the Western United States
Investigators: Atwill, Edward R. , Epperson, William B. , Grotelueschen, D. M. , Sischo, William M. , Smith, B. , Hoar, Bruce , Danaye-Elmi, Cyrus
Current Investigators: Atwill, Edward R. , Epperson, William B. , Grotelueschen, D. M. , Carpenter, L. V. , Smith, B. , Hoar, Bruce , Danaye-Elmi, Cyrus , Brewster, D.
Institution: University of California - Davis , Oklahoma State University , University of Nebraska at Lincoln , South Dakota State University
Current Institution: University of California - Davis , South Dakota State University , University of Nebraska at Lincoln
EPA Project Officer: Hahn, Intaek
Project Period: April 1, 2000 through March 31, 2002 (Extended to February 28, 2002)
Project Period Covered by this Report: April 1, 2000 through March 31, 2001
Project Amount: $248,461
RFA: Drinking Water (1999) RFA Text | Recipients Lists
Research Category: Drinking Water , Water
Objective:
The overall goal of this research project is to establish the prevalence and distribution of genotypes of Cryptosporidium parvum in United States feedlot cattle. In addition, we will quantify the fecal concentration of oocysts from each genotype to estimate oocyst loading rates for this biological source of C. parvum. A secondary objective is to determine management and animal risk factors that are associated with cattle shedding one or more genotypes of C. parvum.Progress Summary:
Our original geographical focus for the multistate cross-sectional survey of feedlot cattle was California, Nebraska, Washington, South Dakota, and Colorado. We are pleased to have added two additional states with large feedlot cattle populations, Texas and Oklahoma, making an overall enrollment of seven states located throughout the central and western United States. As of July 1, 2001, we have sampled approximately 240 cattle per feedlot from one to two feedlots from each of the seven states, resulting in 3,121 cattle being tested. Using a direct immunofluorescent assay (DFA) that can reliably detect 600 oocysts or greater per gram of fecal material (Pereira, et al., 1999; Hoar, et al., 2000), we have identified 8 cattle actively shedding presumptive C. parvum oocysts out of the 3,121 tested. To confirm that our DFA diagnostic method is not falsely classifying fecal samples as negative, we are testing an additional 10 randomly chosen samples per feedlot using immunomagnetic separation of oocysts, followed by our standard direct immunofluorescent assay (IMS-DFA). We have shown previously that our IMS-DFA method can detect as few as 1 oocyst per gram of bovine fecal material (Pereira, et al., 1999). Of the 130 DFA-negative samples tested to date, one sample contained approximately 1 to 4 oocysts/g based on IMS-DFA, suggesting that false negatives are only rarely occurring in our dataset. Using a nested PCR-RFLP technique developed by Xiao, et al., 1999, of the Centers for Disease Control and Prevention that targets the 18S rRNA gene, four of these eight presumptive C. parvum isolates have been confirmed as C. parvum, bovine genotype A (Xiao, et al., 1999, 1999a). The remaining four untyped isolates had extremely low amounts of oocysts, making genotyping a technical challenge. Of the four genotyped isolates, DNA sequencing of the inner (nested) PCR product of 831 to 834 bp has confirmed that the DNA sequence matches the 18s rRNA of more than 50 cataloged isolates of C. parvum.Preliminary inferences from the first year of work are that feedlot cattle located throughout central and western United States are not serving as a major environmental source of C. parvum. We want to stress that we still have more than 3,000 cattle to examine, so valid and precise conclusions should not be formed until the cross-sectional survey is completed. In particular, we will be statistically modeling the survey data to determine the oocyst loading rate for this cohort of adult cattle. It is this parameter, the oocysts loading rate, that is the primary parameter of public health interest and an ideal parameter for risk assessment applications, not the overall prevalence of fecal shedding (Hoar, et al., 2000).
Future Activities:
Our original objective was to survey approximately 240 cattle from each of 24 different feedlots, resulting in approximately 6,000 cattle from the central and western United States. This large effort in sampling cattle from different feedlots and enumerating and genotyping C. parvum isolates will govern our next 12 months of activity. We expect to finish field sampling around December 2001, approximately 3 months later than originally anticipated; therefore, we anticipate requesting a 12-month no-cost extension to conclude field work and genotyping, and to perform detailed statistical modeling of the oocyst loading rate for this cohort of cattle.Journal Articles on this Report : 1 Displayed | Download in RIS Format
Other project views: | All 9 publications | 2 publications in selected types | All 2 journal articles |
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Type | Citation | ||
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Hoar BR, Atwill ER, Farver TB, Jones T. Estimating maximum possible environmental loading amounts of Cryptosporidium parvum attributable to adult beef cattle. Quantitative Microbiology 2000;2(1):21-36. |
R828038 (2000) |
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Supplemental Keywords:
loading, watersheds, livestock, risk assessment, beneficial management practices, pathogens, epidemiology, agriculture, central and western, cross-sectional survey., RFA, Scientific Discipline, Water, Nutrients, Environmental Chemistry, Health Risk Assessment, Biochemistry, Environmental Monitoring, Drinking Water, cryptosporidium parvum oocysts, Safe Drinking Water, microbial contamination, aquatic ecosystem, agriculturally impacted watershed, anthropogenic stress, monitoring, microbial risk assessment, feedlot cattle, water quality parameters, waterborne disease, genotype distribution, bacteria, exposure and effects, DNA sequencing, fecal contamination, zoonotic parasite, other - risk assessment, exposure, drinking water distribution system, public health, comprehensive nutrient management program, dairy farms, agricultrual environment, water quality, drinking water contaminants, immunofluorescent assay, drinking water systemProgress and Final Reports:
Original AbstractThe perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.