title: Molecular survey of trichostrongyle nematodes in a Bison bison herd experiencing clinical parasitism, and effects of avermectin treatment.
abstract: North American bison (Bison bison) producers face many challenges, including the potential clinical and economics problems caused by trichostrongyle nematodes within their herds. Little is known about the prevalence, intensity, geographical distribution and clinical significance of these parasites in commercial bison herds, even from regions where bison production has become popular. This study involved a large herd of bison from eastern South Dakota that was experiencing clinical parasitism due to a temporary over-stocking problem. After documenting fecal egg counts (FECs) and trichostrongyle genera present among the 3 main age-categories (i.e. adults, yearlings, calves) of bison during this heavily infected grazing season, the effects of doramectin treatment on the different age groups was also evaluated. This is the first bison study using PCR to identify genera of trichostrongyles in fecal samples. Virtually all 103 bison fecal samples from all 3 age classes were shedding trichostrongyle eggs by the end of the season, and the mean FECs were 34 eggs/g (EPG) among the cows, 125 EPG in the yearlings, and 186 EGP among calves. Based upon this heavily-infected herd, there is evidence that the susceptibility of bison to trichostrongyles is more similar to beef cattle than to sheep. Other parasites such as Moniezia, Nematodirus, Trichuris, and coccidians were also identified in these samples. All but 3 of the 51 samples analyzed with PCR shown at least 1 trichostrongyle genera. Ostertagia was detected in 68.6% of the samples, Cooperia in 80.39%, Haemonchus in at least 73% and Trichostrongylus in 16% of the herd. Most commonly, bison were infected with combinations of Haemonchus/Ostertagia/Cooperia. After treatment with doramectin, the mean FECs dropped by 99.9% for all of the bison age classes.
authors: Departments of Biology & Microbiology and Veterinary & Biomedical Sciences, South Dakota State University, Brookings, SD 57007, United States; Departments of Zoology, University of Omar Almukhtar, Al Bayda, Libya and University of Benghazi, Benghazi, Libya.
authors: A A
authors: AA
authors: Eljaki
authors: Departments of Biology & Microbiology and Veterinary & Biomedical Sciences, South Dakota State University, Brookings, SD 57007, United States; Department of Parasitology. Faculty of Veterinary Medicine, Mansoura University, Mansoura, Dakahlia Governorate 35516, Egypt.
authors: Y M
authors: YM
authors: Al Kappany
authors: Departments of Biology & Microbiology and Veterinary & Biomedical Sciences, South Dakota State University, Brookings, SD 57007, United States.
authors: D D
authors: DD
authors: Grosz
authors: Department of Natural Resources, South Dakota State University, Brookings, SD 57007, United States.
authors: A J
authors: AJ
authors: Smart
authors: Departments of Biology & Microbiology and Veterinary & Biomedical Sciences, South Dakota State University, Brookings, SD 57007, United States. Electronic address: michael.hildreth@sdstate.edu.
authors: M B
authors: MB
authors: Hildreth
mesh_terms: D000818:Animals; D000871:Anthelmintics / Q000627:therapeutic use*; D016164:Bison; D005260:Female; D007559:Ivermectin / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000627:therapeutic use; D008297:Male; D014251:Trichostrongyloidea / Q000302:isolation & purification*; D014252:Trichostrongyloidiasis / Q000145:classification / Q000188:drug therapy / Q000662:veterinary*
chemical_list: D000871:Anthelmintics; D007559:Ivermectin; C084101:doramectin
keywords: Aggregation; Bison bison; Doramectin; Haemonchus; Nematode; PCR; Trichostrongyle