Date of Graduation

5-2023

Document Type

Thesis

Degree Name

Bachelor of Science in Agricultural, Food and Life Sciences

Degree Level

Undergraduate

Department

Animal Science

Advisor/Mentor

Rogers, Lauren

Committee Member/Reader

Powell, Jeremy G.

Committee Member/Second Reader

Littlejohn, Brittni

Abstract

Bovine Anaplasmosis is an infectious, hemolytic disease transmitted by the rickettsia parasite Anaplasma marginale in cattle. A. marginale parasitizes the red blood cells of an animal throughout their lifetime. The beef cattle industry is the fifth largest agricultural commodity in Arkansas, so potential economic losses due to bovine anaplasmosis is a critical issue. Previously tested beef cattle herds at the University of Arkansas’ Savoy and Batesville units have tested seropositive for A. marginale with low percent inhibitions; however, all seropositive animals tested negative for infection on DNA analysis. The objective of this study was to determine the current infection status of individuals within the two beef cattle herds that have previously tested seropositive for A. marginale and to potentially identify a similar pathogenic organism that may contribute to antibody cross-reactivity. Historically, herd management recommendations have been based on serological testing; however, producers could potentially be making decisions on which cows to treat or cull based on false positive results. Whole blood samples were analyzed for active infection with A. marginale through quantitative Polymerase Chain Reaction (qPCR) testing and blood serum samples were analyzed for anti-Anaplasma antibodies through Competitive Enzyme-linked Immunosorbent Assay (c-ELISA) testing. Additionally, IDEXX 4Dx snap testing and qPCR was performed to detect Ehrlichia spp. and assess potential cross-reactivity of pathogens. Among the two research herds, there were 44 previously seropositive cows available for re-evaluation. 10 were seropositive for A. marginale, 10 were seropositive for Ehrlichia spp., and no cows tested positive for active infection with either rickettsial species. Of the 10 A. marginale seropositive cows, only 50% also showed an antibody response to Ehrlichia spp. The results of testing contribute valuable information to ongoing research regarding the prevalence of A. marginale and/or Ehrlichia spp. within the university’s beef cattle herds.

Keywords

Anaplasmosis; Beef cattle; Anaplasma marginale; qPCR; cELISA; Ehrlichia

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