White footed deer mice (Peromyscus leucopus) serve as the primary natural host for the Lyme disease organism, Borrelia burgdorferi. The Lower Peninsula (LP) of Michigan is not yet completely colonized by B. burgdorferi; even though P. leucopus is present in every county of the state, infected mice have only been found in the southern and western part of the LP. We analyzed both genetic and demographic data from P. leucopus collected in Cheboygan County at the northern tip of the LP to see if B. burgdorferi infection in mice has spread further north in the last two years.
We prepared DNA samples from mouse tissue collected in Cheboygan County in 2023 and 2024, then PCR-amplified part of a gene specific to Borrelia burgdorferi (OSP outer surface protein) in the mouse DNA samples. The products from the PCR were run through gel electrophoresis to determine whether the mice were infected or not infected with B. burgdorferi. The gel was imaged, allowing for observation of the presence/absence of bands, which indicate B. burgdrferi infection. Collected data were compared to previous data to track whether B. burgdorferi is present in the northernmost county of Michigan’s Lower Peninsula, Cheboygan County. Additionally, PCR amplification of mouse mitochondrial DNA is being used to confirm the species identity of each mouse sampled.
Our research thus far indicates that no mice from Cheboygan County are infected with Lyme disease. We will continue to identify positive and negative mouse samples collected during the coming summer in Cheboygan County, as well as from nearby counties. This research has allowed us to gain insights into the diverse susceptibilities of mouse hosts to B. burgdorferi infection, consequently enhancing our comprehension of Lyme disease transmission dynamics.
Author(s): Brooke Smarick, Ally Gitler
Advisor(s): Susan Hoffman, Biology