Poster Presentation 64th International Conference of the Wildlife Disease Association 2015

Differential infection dynamics and susceptibility to Baylisascaris procyonis in Peromyscus species.  (#120)

Sarah G.H. Sapp 1 2 , Sara Weinstein 3 , Christipher McMahan 4 , Michael J. Yabsley 2 5
  1. Department of Infectious Diseases, University of Georgia, Athens, GA, USA
  2. Southeastern Cooperative Wildlife Disease Study, University of Georgia, Athens, GA, USA
  3. Department of Ecology, Evolution, and Marine Biology, University of California , Santa Barbara, CA, USA
  4. Department of Mathematical Sciences, Clemson University, Clemson, SC, USA
  5. Warnell School of Forestry and Natural Resources, University of Georgia, Athens, GA, USA

Deer mice (Peromyscus spp.) are intermediate hosts for Baylisascaris procyonis (raccoon roundworm) and P. leucopus likely serves an important role in parasite transmission. Although infection has been reported in several Peromyscus species, no data are available on differential susceptibility of the various species. We compared infection dynamics of B. procyonis in four species (P. leucopus, P. maniculatus ssp. bairdii, P. californicus, P. polionotus ssp. subgriseus) across regions of varying habitat types and B. procyonis prevalence. Groups of six captive-bred mice of each species were inoculated per os with one of three doses (~10, ~50, or ~500) of embryonated B. procyonis eggs. Animals were monitored twice daily for clinical sings and behavioral abnormalities and were euthanized at the onset of severe CNS symptoms or at 45-48 days post infection (DPI). Larvae were enumerated in the brain via microscopic examination and in skeletal muscle and visceral organs via artificial digestion with HCl-pepsin. Mortality in the high-dose group was 83% for P. californicus and 100% for the other species. In the medium-dose group, mortality was 33% for P. leucopus, 50% for P. californicus and P. polionotus, and 85% for P. leucopus. No mice were euthanized in the low-dose group in P. leucopus, P. californicus, and P. polionotus; one P. maniculatus was euthanized in the low-dose group. Survival data were analyzed using a Weibull regression model. Overall, P. leucopus had greater survival than P. maniculatus, P. californicus, and P. polionotus, which did not differ significantly from each other. Interestingly, larval recovery rates were nearly identical across species and doses. These data indicate that P. leucopus is less likely to develop acute severe disease compared to the other species, and that even closely-related rodents may experience differential mortality. Additionally, natural mortality of rodents due to B. procyonis may be higher than currently recognized.