Research Summary - 3
Evaluation of BLV Antibodies in Milk Samples Tested for H5N1 in U.S. Dairy Cattle
| Date/Time: |
8/29/2026
11:15
|
| Author: |
Devi P Patnayak |
| Clinic: |
University of Minnesota, Veterinary Diagnostic Laboratory |
| City, State, ZIP: |
St Paul, MN 55108 |
Devi P. Patnayak, DVM, Ph D
1
;
Jennifer Larson, BS
1
;
Elisa Melendez, BS
1
;
Michele Leiferman, BS
1
;
Faatima Zahra Laabouri, DVM, Ph D
2
;
Hemant K. Naikare, DVM, Ph D
1
;
1University of Minnesota, Veterinary Diagnostic Laboratory, St Paul MN 55108
2Department of Medicine, Surgery and Reproduction, Agronomic and Veterinary Institute Hassan II, Rabat, Morocco
Introduction:
Highly pathogenic avian influenza caused by avian influenza A (H5N1) was detected in U.S. dairy cattle in 2024, marking an unprecedented expansion of the virus’s host range and raising important One Health concerns. Disease impact varies across farms, with lactating cows most affected. Morbidity is generally below 10 percent and mortality or culling is 2 percent or less. Affected cattle are often asymptomatic or show mild signs such as reduced milk production, thickened colostrum like milk, decreased appetite, lethargy, fever, and dehydration. Co infections may influence transmission or severity, and bovine leukemia virus, which is widespread in U.S. dairy herds, is a potential contributing factor. No published reports have documented co infection of BLV and HPAI in cattle, underscoring the need to determine whether BLV influences infection dynamics or disease expression.
Materials and methods:
Two sets of milk samples, either individual or bulk tank, were tested. The first set included 184 individual milk samples collected from a dairy farm experiencing an influenza outbreak. The second set comprised 273 bulk tank or individual samples from farms confirmed negative for influenza by PCR and ELISA. Both the influenza A matrix real time PCR and the IDEXX Swine Influenza Virus Antibody ELISA were validated for use with milk according to National Animal Health Laboratory Network standard operating protocols. BLV antibody ELISA kit (VMRD) was used to detect the BLV antibodies in milk as per manufacturer’s recommendations and Evermann et. al. (JVDI 2019).
Results:
In the first set, 184 samples were tested by PCR in pools of five, yielding 37 pools. One pool was positive by influenza A matrix PCR, and individual testing with H5N1 real time PCR identified one positive cow. ELISA detected influenza antibodies in 96 cows, with 13 additional suspect results. BLV antibodies were detected in 102 cows, although influenza positive cows were not necessarily BLV positive. In the second set, none of the 273 samples were positive for influenza by PCR or ELISA. However, BLV antibodies were detected in 180 samples (65.93 percent).
Significance:
These findings do not establish BLV as a co morbidity factor, as BLV antibodies were also common in samples from influenza negative farms.
