Semester of Graduation

Summer 2026

Degree

Master of Science (MS)

Department

School of Animal Sciences

Document Type

Thesis

Abstract

Fasciola hepatica, the common liver fluke, is endemic in the Pacific Northwest and Gulf Coast of the United States. To provide updated information on F. hepatica prevalence, as part of the USDA National Animal Health Monitoring System Sheep 2024 study, sheep operations in the top 30 sheep-producing states were identified, and producers were invited to participate. For each operation, feces were collected from at least eight sheep and pooled to form a single composite sample. Two methods were used to identify sheep infected with F. hepatica: fecal sedimentation and indirect sandwich ELISA. At the national level, across 318 operations, 7.1 ± 1.4% of operations had sheep that tested positive for F. hepatica by sedimentation, ELISA, or both. At the regional level, the respective prevalences for the Western, Central, Northeast, and Southeast regions were 16.5 ± 4.8%, 9.2 ± 2.8%, 5.3 ± 1.9%, and 2.1 ± 2.0%. The parasite was found in 11.5 ± 4.5% of operations in Wisconsin, Indiana, and Michigan, where F. hepatica had not previously been reported. The presence of the parasite in endemic areas was expected. However, its apparent presence in the Great Lakes region is a concern, suggesting that the parasite may have expanded its distribution into areas previously free of the fluke. These results provide an update on the known distribution of F. hepatica. They should guide the veterinary community in searching for this parasite in areas where it was not previously thought to occur.

Date

7-26-2026

Committee Chair

Williams, Cathleen

LSU Acknowledgement

1

LSU Accessibility Acknowledgment

1

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