A deadly strain of bird flu, D1.1, has been detected in Nevada’s cow herds, raising alarm about its potential impact on public health and the dairy industry.
At a Glance
- Four cattle herds in Nevada tested positive for the D1.1 strain of H5N1 bird flu
- D1.1 has been linked to a fatal human case in Louisiana
- The strain causes more severe symptoms in humans compared to other variants
- Nearly a thousand cow herds across 16 states have been infected with bird flu
- Enhanced biosecurity measures are crucial to prevent further spread
New Strain Detected in Nevada Cattle
The U.S. Department of Agriculture’s Animal and Plant Health Inspection Service has confirmed the presence of a new strain of H5N1 bird flu, known as D1.1, in milk samples from dairy herds in Nevada. This unexpected development has raised concerns about the virus’s ability to transmit between species and its potential impact on both animal and human health.
The D1.1 strain, previously associated only with migrating birds and poultry, has now been detected in at least four cattle herds in Churchill County, Nevada. This marks a significant shift in the virus’s behavior, challenging previous assumptions about its transmission patterns.
The symptoms observed in cows infected with D1.1 are similar to those seen in previous bird flu outbreaks. Ciara Ressel, a Spokesperson for the Nevada Agriculture Department, described the symptoms:
“Symptoms of H5N1 D1.1 have been similar to the detections of B3.13. These include fever, reduced feed consumption, reduced milk production and mild respiratory signs (coughing, sneezing, runny nose),” Ciara Ressel, Nevada Agriculture Department spokesperson said.
While the risk to human health remains low, the D1.1 strain has been linked to a fatal human case in Louisiana. This underscores the potential severity of the virus if it were to spread more widely to humans. The Centers for Disease Control and Prevention (CDC) reports that 40 out of 67 human bird flu cases since 2024 are linked to dairy cows, with the rest resulting from poultry exposure.
Impact on the Dairy Industry
The discovery of D1.1 in dairy cows has significant implications for the agricultural sector. Nearly a thousand cow herds across 16 states have been infected with bird flu, with recent cases mostly concentrated in California. The spread of the virus to cattle challenges the dairy industry and raises concerns about potential economic impacts.
The USDA’s National Milk Testing Program, which covers 38 states, played a crucial role in detecting the virus. This discovery has prompted calls for the development of a bovine vaccine to prevent further spread among cows.
In light of these developments, health officials and agricultural experts are emphasizing the importance of enhanced biosecurity measures. State veterinarian Peter Rolfe stressed the critical nature of these precautions:
“It is critical that animal health biosecurity practices are enhanced to help prevent the spread of disease and protect animal and worker safety,” Peter Rolfe said.
The USDA is conducting further investigations to understand and limit the disease spread. While the agency’s HPAI eradication strategy remains unchanged, the situation underscores the need for vigilance and adaptability in addressing emerging threats to animal and public health.
