Publication Date

Spring 2016

Advisor(s) - Committee Chair

Carl Dick (Director), Cheryl Davis, and Michael Stokes

Degree Program

Department of Biology

Degree Type

Master of Science

Abstract

Many zoonotic pathogens of concern to human and veterinary health are maintained in the environment within small mammal reservoirs and vectored to new hosts by ectoparasitic arthropods. While the ecological relationships among small mammals, ectoparasites, and disease-causing symbiotic microorganisms are important to these dynamics, little is known about them across much of North America. The sylvatic cycle of Borrelia burgdorferi, the etiologic agent of Lyme disease, is of particular interest because Lyme disease is the most common vector-borne disease of humans in the United States. However, cases of Lyme disease are primarily confined to the northeastern and Midwestern United States, with only sporadic cases extending into the southeast. As a result, much of what is known of the ecology of Lyme disease comes from studies conducted in those regions. The goal of this study was to examine the ecological dynamics of the B. burgdorferi/vector/reservoir system in south-central Kentucky and gain insight into the relative paucity of Lyme disease in Kentucky. Small mammals were captured using live traps in three 200x50 m trapping grids within Western Kentucky University’s Green River Preserve from November 2014-October 2015. Captured small mammals were identified to species and standard measurements were recorded. Ectoparasites were removed and retained for identification. Collected blood and tissue were examined for B. burgdorferi DNA by polymerase chain reaction with primers specific to the OspA gene. The Bray-Curtis dissimilarity index, Schnabel population estimates, and the Shannon-Wiener diversity index were used to assess the structure of the small mammal communities. Parasite infestation was low but was affected by age and sex of the host, site, and season in different parasite taxa. Infestation by Ixodes scapularis, the primary vector for B. burgdorferi, was uncommon and prevalence of B. burgdorferi in blood was similar to the lowest prevalence previously observed in the Lyme disease endemic regions. We found that life history characteristics of hosts and ectoparasites drive their associations. We also suggest that the lack of an efficient vector for B. burgdorferi is the likely explanation for the few reported cases of Lyme disease in Kentucky.

Disciplines

Entomology | Forest Biology | Other Animal Sciences

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