Differential burdens of blacklegged ticks (Ixodes scapularis) on sympatric rodent hosts

Authors: BROWN, JESSICA - Pennsylvania State University; TIFFIN, HANNAH - Pennsylvania State University; PAGAC, ALEXANDRA - Pennsylvania State University; Poh, Karen; EVANS, JESSE - Pennsylvania State University; MILLER, TAYLOR - Pennsylvania State University; HERRIN, BRIAN - Kansas State University; TOMLINSON, TREY - Kansas State University; SUTHERLAND, CAMERON - Kansas State University; MACHTINGER, ERIKA - Pennsylvania State University

Submitted to: Journal of Vector Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/5/2023
Publication Date: 12/21/2023
Citation: Brown, J.E., Tiffin, H.S., Pagac, A., Poh, K.C., Evans, J.R., Miller, T.M., Herrin, B.H., Tomlinson, T., Sutherland, C., Machtinger, E.T. 2023. Differential burdens of blacklegged ticks (Ixodes scapularis) on sympatric rodent hosts. Journal of Vector Ecology. 49(1):44-52. https://doi.org/10.52707/1081-1710-49.1.44.
DOI: https://doi.org/10.52707/1081-1710-49.1.44

Interpretive Summary: The number of tick-borne disease cases has been increasing over the past decade, with the largest increase of cases seen with Lyme disease. In the Lyme disease cycle, the bacterial agent Borrelia burgdorferi is transmitted by the blacklegged tick Ixodes scapularis. In addition, small mammal hosts play a large role as reservoirs that serve to amplify the bacterium, thereby infecting other ticks that feed on that host. Most notably, the white-footed mouse (Peromyscus spp.) is considered the major reservoir for B. burgdorferi. To understand if additional small mammal hosts may play a role in the Lyme disease cycle, this study compared tick burdens and pathogen prevalence in southern red-backed voles (Clethrionomys gapperi) and white-footed mice (Peromyscus spp.) found in forested areas during the summer. Adult white-footed mice had significantly higher burdens of ticks compared to adult southern red-backed voles. In addition, 65.8% of white-footed mice samples that were tested for pathogens were positive for B. burgdorferi, while only 10.2% of southern red-backed vole samples were positive. As more host-specific tick control methods continue to be developed, it is important to consider and target all potential tick hosts to maximize tick control efforts.

Technical Abstract: In the United States, there has been a steady increase in diagnosed cases of tick-borne diseases in people, most notably Lyme disease. The pathogen that causes Lyme disease, Borrelia burgdorferi, is transmitted by the blacklegged tick (Ixodes scapularis). Several small mammals are considered key reservoirs of this pathogen and are frequently-used hosts by blacklegged ticks. However, limited studies have evaluated between-species host use by ticks. This study compared I. scapularis burdens and tick-associated pathogen presence in wild-caught Clethrionomys gapperi (southern red-backed voles) and Peromyscus spp. (white-footed mice) in forested areas where the habitat of both species overlapped. Rodent trapping data collected over two summers showed a significant difference in the average tick burden between species. Adult Peromyscus spp. had an overall mean of 4.03 ticks per capture, while adult C. gapperi had a mean of 0.47 ticks per capture. There was a significant association between B. burgdorferi infection and host species with more Peromyscus spp. positive samples than C. gapperi (65.8% and 10.2%, respectively). This work confirms significant differences in tick-host use and pathogen presence between sympatric rodent species. It is critical to understand tick-host interactions and tick distributions to develop effective and efficient tick control methods.