Date of Award

January 2023

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

First Advisor

Jefferson Vaughan

Abstract

Lyme disease, caused by Borrelia burgdorferi, is currently the most prevalent vector borne disease in North America. With the CDC estimating almost 500,000 new cases every year, methods are needed to control the vector, the black legged tick (Ixodes scapularis). Like other tick-borne diseases, Lyme disease is zoonotic and involves tick parasitism on rodent reservoirs in the wild. The main reservoir host of Lyme disease is the white-footed mouse (Peromyscus leucopus). This study aims to explore the effectiveness of a reservoir targeted control approach by the treatment of white-footed mice with oral isoxazoline class drugs. We aim to understand the effectiveness and length of protection of isoxazoline drugs in mice against both black-legged ticks and American dog ticks as well as any protection that may be passed from nursing mice to offspring through drug residue in milk.A white-footed mouse colony was established from wild mice caught in Grand Forks, ND. Pathogen free larval black legged and American dog ticks were obtained from the CDC through BEI Resources. Mice were treated once orally with 50mg/kg bodyweight of a selected commercially available isoxazoline drug (afoxolaner, fluralaner, lotilaner). Control mice received no treatment. After treatment mice were infested with serial tick infestations at various time points to test for acaricidal activity. Mice were anesthetized with a pentobarbital injection and 20 larval ticks of both species were applied. Mice were placed in wire bottom cages suspended over a tray of water. Tick drop-off was recorded for five days. Mother mice were also treated with lotilaner to determine if acaricidal activity might be passed to their offspring. A high-dose treatment mother received three weekly treatments throughout her 23-day nursing period while a low-dose treatment mother received only one treatment on post-partum day 10. Control mothers did not receive treatment. After weaning, pups were exposed to serial larval tick infestations. The number of successful engorged larval ticks that detach from control mice were compared with the number of engorged ticks that detached from treated animals. All isoxazolines provided a decrease in engorged ticks in treated mice with lotilaner providing the longest duration of protection of up to 2 months. Lotilaner was transferred to nursing pups and provided pups with up to 2 weeks of protection against tick attachment.

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