Seroprevalence and molecular detection of Anaplasma marginale infected beef herds in Georgia, USA
Keywords:Anaplasma marginale, anaplasmosis, beef cattle, Georgia, seroprevalence
The objective of the study was to conduct and compare seroprevalence and molecular detection of Anaplasma marginale-infected beef herds in Georgia, and to identify herd risk factors associated with A. marginale-positive herds. Herd information from the beef operations was collected from the sampled herds through a questionnaire to determine practices that may affect the risk of herd infections with A. marginale. Blood samples were collected from 1,059 adult beef cattle (≥ 2 years) from 33 herds. Overall, 8.12% of cattle and 42% of herds were cELISA antibody-positive. Seventy-seven percent of plasma samples from a subset of corresponding seropositive samples (n = 73) were PCR positive. All of the 406 seronegative samples were negative by PCR. There was almost perfect agreement by Cohen’s kappa statistics between PCR and cELISA (k = 0.85). Survey response rate was 100%. Surprisingly, 27% of the producer respondents had not heard of anaplasmosis. Survey also revealed that many producers had management procedures at their operations that could potentially cause mechanical transmission of A. marginale. About 55% of respondents did not always disinfect tools between animals and 88% of the operations used the same needle to inject more than one animal. Over 80% of the producer respondents had brought in new cattle onto their operations in the last 3 years from the time of this study. Given the 8% seroprevalence in Georgia beef cattle and the reported survey findings from this study, educational programs on effective preventive management practices to control bovine anaplasmosis is warranted.