Degree

Doctor of Philosophy (PhD)

Department

School of Animal Sciences

Document Type

Dissertation

Abstract

Bovine anaplasmosis is an infectious, non-contagious, hemolytic disease of cattle that is caused by the organism Anaplasma marginale (A. marginale). Ticks (Dermacentor variabilis and Dermacentor andersoni) are the primary biological vectors, and mechanical vectors include biting insects or by blood-contaminated fomites including needles, ear tagging, tattooing, dehorning, and castration equipment. Therefore, the objectives of this study were to 1) evaluate management practices that may contribute to bovine anaplasmosis herd infection; 2) estimate the prevalence of bovine anaplasmosis in Louisiana cow-calf herds; and 3) validate the Pluslife Anaplasma/Ehrlichia Nucleic Acid Test Kit for use in cattle. Louisiana cattle producers (n = 62) completed an online Qualtrics survey that included questions on producer demographics, herd demographics, health management, and biosecurity approved by the Louisiana State University Agricultural Center IRB (IRBAG-24-0117). Survey questions were used to infer how management practices relate to bovine anaplasmosis infection status. Chi-square tests were used to determine associations between several management practices and anaplasmosis diagnosis. Factors found to be significant or suggestive were included in a logistic binary regression model to test for significance. According to survey results, neighboring herd diagnosis (OR = 10.839, 95% CI: 2.041-57.566, p = 0.005), use of tattoos (OR = 5.124, 95% CI = 0.974-26.961, p = 0.054), and calving season length (OR = 28.00, 95% CI = 1.35-580.59, p = 0.031) were all predictors of anaplasmosis status. Blood samples were collected from 256 mature cows from 26 herds across five regions between March and September 2025 to estimate disease prevalence. Based on cELISA testing, the herd-level prevalence was 57.7%, and the individual cow prevalence was 19.1%. A multilevel binary logistic regression was conducted to assess whether the odds of a positive test result varied across the five regions. Region was not a significant predictor of anaplasmosis diagnosis. Sixteen cELISA positive and sixteen cELISA negative blood samples were used in an attempt to validate the Pluslife Anaplasma/Ehrlichia Nucleic Acid Test Kit. The kit did not yield interpretable results under the conditions applied. As a result, no statistical analysis could be conducted to evaluate its potential role as a diagnostic test for bovine anaplasmosis.

Date

1-7-2026

Committee Chair

Elzer, Philip H.

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