Grantee Research Project Results
2001 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. , Carpenter, L. V. , Smith, B. , Hoar, Bruce , Danaye-Elmi, Cyrus , Brewster, D. , Riggs, W.
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 Omaha , 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, 2001 through March 31, 2002
Project Amount: $248,461
RFA: Drinking Water (1999) RFA Text | Recipients Lists
Research Category: Drinking Water , Water
Objective:
The overall objectives for this research project are to: (1) quantify the fecal concentration of genotypes of Cryptosporidium parvum in United States feedlot cattle to estimate the oocyst loading rate for this sector of animal agriculture; (2) establish the prevalence and distribution of various genotypes of C. parvum in populations of feedlot cattle; and (3) identify management and animal risk factors that are associated with feedlot cattle shedding one or more genotypes of C. parvum.
Progress Summary:
The project was originally designed for a 2-year duration, but we requested and received a 1-year, no-cost extension given the large amount of field sampling occurring within this project. We have sampled approximately 240 cattle per feedlot, with 22 feedlots enrolled in the project. Samples were taken from feedlots located in California, Washington, Texas, Oklahoma, Colorado, South Dakota, and Nebraska. This sampling design resulted in 5,274 cattle being examined for C. parvum oocyst shedding. Within each feedlot, fecal samples were collected from sets of cattle that had just arrived, been at the feedlot 4 to 8 weeks, and from cattle weeks prior to slaughter. This allowed us to determine if days on feed and the composition of the ratio (forage:concentrates) influenced the likelihood of C. parvum shedding in fed cattle. Out of these 5,274 fecal samples, only 9 (0.2 percent) had detectable levels of oocysts as measured by the direct immunofluorescent assay. The direct immunofluorescent assay can reliably detect oocyst concentration down to about 600 oocysts per gram of feces. To determine if a percentage of cattle was shedding small numbers of oocysts, we retested 10 negative cattle from each feedlot using immunomagnetic separation of oocysts, followed by direct immunofluorescence. Only 2 out of 220 fecal samples contained low levels of oocysts, suggesting a low false negative occurrence in our data. We are in the process of statistically analyzing this dataset for Objective 1 (environmental loading rate) using methods developed, in part, in our laboratory (Hoar B, Atwill ER, Farver TB. Estimating maximum possible environmental loading amounts of C. parvum attributable to adult beef cattle. Quantitative Microbiology 2000;2:21-36).
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, the genotype of these isolates was the bovine genotype A, as described in: Xiao L, Morgan UM, Limor J, et al. Genetic diversity within C. parvum and related Cryptosporidium species. Applied and Environmental Microbiology 1999;65:3386-3391. To supplement the genotyping data of C. parvum oocysts from feedlot cattle, we will genotype additional isolates of Cryptosporidium obtained from various livestock and wildlife species.
Although we have not yet calculated the environmental loading rate of C. parvum bovine genotype A from feedlot cattle, these preliminary data suggest that feedlot cattle are not a major reservoir of C. parvum. This lack of substantial shedding of C. parvum among feedlot cattle is a positive finding, despite some drawbacks. Feedlots are located throughout the United States, and some of these feedlots are located on critical watersheds. In addition, feedlots can produce large amounts of fecal material on a per acre basis. Lastly, the infectious potential of bovine C. parvum exists for susceptible humans.
Future Activities:
During the next reporting period, we will be finalizing our evaluation of the sensitivity of the diagnostic assays used in the project, genotyping recently acquired isolates of C. parvum from livestock and wildlife, performing statistical analyses, and preparing manuscripts.Journal Articles:
No journal articles submitted with this report: View all 9 publications for this projectSupplemental Keywords:
loading, watersheds, livestock, risk assessment, beneficial management practices, pathogens, epidemiology, agriculture, central and western, cross-sectional survey, bovine, protozoa., RFA, Scientific Discipline, Water, Health Risk Assessment, Environmental Chemistry, Biochemistry, Nutrients, Drinking Water, Environmental Monitoring, microbial contamination, dairy farms, agricultrual environment, DNA sequencing, Safe Drinking Water, water quality, water quality parameters, aquatic ecosystem, microbial risk assessment, fecal contamination, monitoring, drinking water system, drinking water contaminants, exposure, other - risk assessment, waterborne disease, agriculturally impacted watershed, cryptosporidium parvum oocysts, genotype distribution, zoonotic parasite, comprehensive nutrient management program, drinking water distribution system, feedlot cattle, immunofluorescent assay, public health, anthropogenic stress, bacteria, nutrient managementProgress 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.