Research Summary - 2

Surveillance of Anaplasma marginale in Arkansas beef cattle herds

Date/Time: 9/25/2020    08:45
Author: Lauren R Thomas
Clinic: University of Arkansas, Department of Animal Science
City, State, ZIP: Fayetteville, AR  72701

G. L. Apple, BS 1 ; L. R. Thomas, DVM 1 ; H. M. Ward, DVM, PhD 4 ; K. E. Reif , MS.P.H., PhD 2 ; T. Anantatat, BS 2 ; M. Flowers, BS 2 ;
1University of Arkansas, Department of Animal Science, Fayetteville, AR 72701
2Kansas State University, College of Veterinary Medicine, Manhattan, KS 66506
3University of Arkansas, Veterinary Diagnostic Laboratory, Fayetteville, AR 72701
4University of Arkansas, Cooperative Extension Service, Little Rock, AR 72204


The objective of this study was to utilize both polymerase chain reaction (PCR) and competitive enzyme-linked immunosorbent assay (cELISA) tests to determine the general prevalence of A. marginale in Arkansas beef cattle within six different geographical regions of the state. Anaplasmosis is an economically devastating disease in cattle that is caused by the rickettsial parasite Anaplasma marginale. It is estimated that this parasite causes over $300 million in expenses for the U.S. cattle industry annually. In Arkansas, the beef cattle industry is the fifth largest agricultural commodity in the state. As a result, a better understanding of this disease and its prevalence within the state is needed.

Materials and Methods:

The work presented here is a collaborative effort between the University of Arkansas and the Kansas State University College of Veterinary Medicine. Ultimately, a total of 578 mature beef cattle, all over 2 years of age, were randomly selected from across Arkansas for sampling. Both whole blood and serum samples were collected from each animal. PCR testing was completed on each whole blood sample submitted at the KSU College of Veterinary Medicine, while cELISA testing was completed on each serum sample by the University of Arkansas Veterinary Diagnostic Laboratory.


A total of 335 (58.7%) blood samples were positive on at least one of the two tests. A majority of the animals that tested positive (229, 68.4%) were found to be positive on both the cELISA and PCR tests. Rates of regional seroprevalence and/or PCR prevalence ranged from 36.7% to 93.8%. Overall, the highest percent prevalence was found along Crowley’s Ridge in the northeastern corner of the Arkansas at 93.8%. The lowest percent prevalence was found in the Ozark and Ouachita Mountain regions at 37.4% and 36.7%, respectively.


The information gathered by this study provides substantial evidence that Anaplasma marginale is endemic to the state of Arkansas. It appears that there is a significant correlation between geographic region and rate of infection. The sample analysis and regional percentages are being distributed to county Extension agents and cattle producers for educational purposes.