Enzootic bovine leukosis (EBL), caused by the bovine leukemia virus (BLV), is a common disease in dairy cattle worldwide, particularly in North America. While only a small percentage of infected cows develop malignant lymphoma, BLV prevalence in U.S. and Canadian dairy herds exceeds 80%, significantly impacting herd health and economic performance. In 2024, the disease is estimated to cause $900 million annually in economic losses to the U.S. dairy industry, primarily due to reduced milk production, increased culling, and higher incidences of mastitis and metritis.
Key Findings:
- Disease Prevalence and Economic Impact: Nearly 90% of U.S. and Canadian dairy herds test positive for BLV, with infected cows experiencing reduced productivity and increased health issues.
- Health Risks: BLV-positive cattle have higher odds of developing subclinical mastitis, metritis, and are more likely to be culled compared to BLV-negative animals.
- Immune Dysfunction: BLV disrupts both innate and adaptive immune responses, weakening immune cell function and triggering inflammatory damage in infected cattle.
- Risk Factors: Practices like milking frequency, infrequent needle changes, bedding type, and larger herd sizes are associated with higher BLV prevalence.
Efforts to mitigate the impact of BLV should focus on improving herd management practices, monitoring proviral loads, and reducing risk factors to protect herd health and economic sustainability.
