PATHOGEN EXPOSURE PATTERNS AMONG SYMPATRIC POPULATIONS OF BIGHORN SHEEP, MULE DEER AND CATTLE

We sampled sympatric bighorn sheep (Ovis canadensis, n = 31), mule dee r (Odocoileus hemionus, a = 38), and domestic cattle (n = 26) in the S an Bernadino Mountains of southern California (USA) for the presence o f Psoroptes spp, mites and for serologic evidence of exposure to bluet ongue virus (BTV) and Babesia spp. From 1991 through 1994, Psoroptes s pp. infestations were found on 12 (44%) of 27 bighorn sheep. No mites were found on mule deer or cattle. The BTV serum antibody prevalence i n a cohort of 26 cattle ranged from 17 to 89%. There was no evidence o f exposure to BTV in the bighorn sheep or mule deer. The cumulative se rum antibody prevalence of Babesia spp, during the study was 35% in 26 bighorn sheep and 85% in 20 mule deer, while antibodies were not dete cted in a cohort of cattle when they were sampled in May (n = 23) and December (n = 22) of 1992. Based on these results, we concluded that i nfestation with Psoroptes spp. and exposure to BTV was limited to bigh orn sheep and cattle, respectively. In contrast, Babesia spp. infectio ns appeared to be common in both mule deer and bighorn sheep while the re was no evidence of exposure in cattle.