Submitted to: Journal of Veterinary Diagnostic Investigation
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/26/2016
Publication Date: 4/1/2017
Publication URL: http://handle.nal.usda.gov/10113/5678130
Citation: Bauermann, F.V., Ridpath, J.F., Dargatz, D.A. 2017. Bovine leukemia virus seroprevalence among cattle presented for slaughter in the United States. Journal of Veterinary Diagnostic Investigation. doi: 10.1177/1040638717702183.

Interpretive Summary: Bovine leukosis virus (BLV) infections lead to major money losses for beef and dairy producers worldwide. While only about 5% of the infected animals show symptoms infected results in lost production and reduced herd health. The duration of infection is prolonged and may last for years. There is no vaccine and or treatment to eliminate BLV once an animal is infected. The virus can be found on the milk and meat of infected animals. No cases of BLV transmission from cattle to humans have been confirmed but there remains a concern that BLV infection may represent a human health hazard. For these reasons, several European countries have embarked on BLV control programs. No control program currently exists in the United States of America (USA). Previous studies in 1996, 1999 and 2007 showed that the BLV virus was present in around 40% of the cattle in the USA. In this study samples were collected from all regions of the contiguous USA. These samples were collected in five slaughter plants and were tested for the presence of antibodies against BLV to provide an updated picture of the virus distribution in the country. It was found that the Northeast region has the highest prevalence (54% positive) while the lowest prevalence was found in the Mountain West region (32%positive). Overall, 38.5% of the tested samples were positive. It was also found that slaughter plants that process primarily dairy animals have higher percent of positive results (47%), than plants that primarily process beef animals (33%). This updated picture is important for monitoring the virus distribution on the country and may help toward implementing a plan to control the disease.

Technical Abstract: Infection with bovine leukemia virus (BLV) results in economic loss due reduced productivity, especially the reduction of milk production and early culling. In the USA.,USA, previous studies in 1996, 1999 and 2007 showed BLV infections widespread, especially in the dairy herds. The goal of this study was to update information on the BLV seroprevalence in the USA. Samples submitted for testing and found brucellosis negative by the Kentucky Federal Brucellosis Laboratory were used. From October 2014 through August 2015 2000 samples from all regions of the contiguous US were selected and tested for BLV antibodies by enzyme-linked immunosorbent assay. The overall percent of samples positive for BLV antibody was 38.5%. Based on the animal’s origin the percent positive by region respectively ranged from 32.4% (Mountain West region) to 54.3% (Northeast region). When the positive rate for slaughter plants that processed mainly beef animals (beef plants) was compared to the positive rate for slaughter plants that processed mainly dairy animals (dairy plants) it was found that the positive rates at dairy plants (47.4%) was higher than the positive rates at beef plants (33.4%). These results suggest that BLV infection remains widespread in all regions of USA and that rates may differ between beef and dairy cattle.