Abstract

We conducted a study of 159 American Black Bears (Ursus Americanus) to establish the occurrence rates of Lyme disease, Rocky Mountain spotted fever (RMSF), babesiosis, Ehrlichiosis, and anaplasmosis as well as the presence of their vectors Dermacentor variabilis and Rhipicephalus sanguineus. There are many factors that influence the prevalence of not only the ticks, but tick-borne diseases as well including seasonal and environmental changes, interactions between humans and their domestic animals, as well as changes observed in the tick and host species themselves. We studied the effects of sex, location, and the presence of fecal parasites based on the tick exposure of the bears. Multivariable logistical regression revealed that sex influences the presence of ticks (p=0.0346) and there was weak evidence for the effect of sex on the presence of fecal parasites (p=0.061). We found no effect of location on the presence of the ticks (p= 0.5487) or fecal parasites (p=0.0908). The presence of ticks in American black bears significantly decreases the presence of fecal parasites (p= 0.0055). All bears sampled in May and June of each year had ticks present. We used the Fisher’s exact test for count data to compare two periods of time. In the years 2003-winter 2005, we found no bears exposed to Lyme disease, Ehrlichiosis (Ehrlichia canis), or Rocky Mountain spotted fever. In summer 2005, we found six bears exposed to Lyme disease, which is significantly greater than the previous years (p=0.003841). Even though we found two bears exposed to Ehrlichiosis in summer 2005, this is not significantly different than the previous years (p= 0.1689). We found three bears were exposed to RMSF, but once again, the difference is not significant than in previous years (p= 0.06757). No bears were exposed to babesiosis (Babesia canis) in any of the years sampled. Based on our results, we found evidence of increased exposure in black bears to babesiosis. This may indicate a one-time increase in exposure or possibly a trend towards increased exposure over time, but additional research would be needed to determine which of these two options is actually the case.

Keywords

Black bear, diseases, reservoirs, exposure, parasites

Document Type

Thesis

Year of Completion

2021

Major

Biology with Pre-Medicial Concentration

Advisor

Dr. Kent Hatch

Academic Department

Biomedical, Health and Nutritional Sciences

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