Spatial clustering of Borrelia burgdorferi sensu lato within chipmunk and woodrat populations in northwestern California
Graduation Date
2014
Document Type
Thesis
Program
Other
Program
Thesis (M.S.)--Humboldt State University, Natural Resources: Wildlife, 2014
Committee Chair Name
Richard Brown
Committee Chair Affiliation
HSU Faculty or Staff
Keywords
Borrelia burgdorferi, Chipmunks, Woodrats, Clustering, Disease, Lyme disease, Spatial, Rodents, Humboldt State University -- Theses -- Wildlife, Habitat, Northern California
Abstract
Lyme borreliosis is recognized as the most common emerging tick-borne disease affecting humans in the United States. In northwestern California, the ecology of Lyme borreliosis is complex, with several potential reservoirs, multiple tick vectors, and multiple genospecies of Borrelia burgdorferi sensu lato. The primary objective of this study was to identify spatial aggregation in rodents positive for various genospecies of Borrelia burgdorferi sensu lato. I looked at spatial clustering of different genospecies within dusky-footed woodrats (Neotoma fuscipes) and Allen's chipmunks (Neotamias senex). Rodents were live-trapped between March of 2004 and August of 2005. Ear punch biopsies were collected to determine presence of borreliae and positive products of polymerase chain reactions (PCR) were sequenced to determine genospecies associations. ArcGIS and Satscan were used to examine spatial clustering of genospecies from rodent samples. Fisher's exact tests and a multinomial log linear model were used to model habitat and species specific characteristics and their effect on genospecies prevalence. Akaike's information criterion (AICc) was used to compare models and determine which model best fit the data. Borrelia burgdorferi sensu stricto was more often associated with chipmunks and B. bissettii was more often associated with woodrats (P = 0.002 and P=0.043, respectively). The top model included "host species", "month", and "location" variables (weight = 0.87). Spatial clustering was found in the northwest and southeast corners of the study area (P ≤ 0.001). My results indicate that location within the study area strongly correlates with genospecies variation among hosts. This suggests a relationship between host species, time of year, borrelial genospecies, and location. These variables seem to be important in the ecology of transmission of borrelial genospecies and may help in determining areas of increased risk of human exposure to these pathogens.
Recommended Citation
Hacker, Gregory M., "Spatial clustering of Borrelia burgdorferi sensu lato within chipmunk and woodrat populations in northwestern California" (2014). Cal Poly Humboldt theses and projects. 987.
https://digitalcommons.humboldt.edu/etd/987
https://scholarworks.calstate.edu/concern/theses/t722hb97j