US dairy herd quarantined after H5N1 detection in Washington state
Routine monitoring identified the infection, with initial testing carried out by the Washington Animal Disease Diagnostic Laboratory. The USDA National Veterinary Services Laboratories subsequently confirmed the finding. Amber Itle, Washington’s state veterinarian, said surveillance had picked up the virus before cattle developed symptoms, and described the detection as its spread into another county.
Itle said dairy farmers were putting their biosecurity plans into practice, applying lessons from previous experience and supporting one another. She praised collaboration between farmers and veterinarians to protect cattle and workers while maintaining operations. She said officials hoped early detection would help them introduce farm measures to curb transmission both within affected premises and between dairy and poultry operations.
Symptoms in dairy cattle can include lower milk output and milk that becomes thicker or turns yellowish-brown. Animals may also eat less, develop a fever or show respiratory signs. Changes in manure and a marked reduction in rumen movement are further signs of infection. Supportive treatment helps most affected animals recover; recovery across an entire herd generally takes between four and six weeks.
Transmission between dairy cattle can involve infected animals or contaminated milk. Equipment used by multiple farms, vehicles, clothing and shoes can also carry the virus, as can wild birds. State authorities advised livestock keepers to restrict transfers of animals between farms and disinfect footwear. They also recommended keeping newly arrived animals isolated for 30 days and housing ill cattle separately from healthy ones.
Officials said dairy products made with pasteurized milk remained safe to consume because the treatment inactivates bacteria and viruses. Infected cattle can release the virus into their milk, making unpasteurized milk and products made from it unsafe. Authorities also advised owners against giving pets either raw milk or raw food products.
The Centers for Disease Control and Prevention and Washington State Department of Health assess the overall risk to public health as low. People whose work involves direct contact with livestock or birds that could be infected face greater risk. Recommended protective equipment for those exposed includes gloves, a mask, protection for the eyes and outer clothing that resists fluids.
The Washington State Department of Agriculture said it would publish news releases when cattle infections were confirmed in counties without previously announced cases. Further detections in counties already covered by an announcement will instead be recorded on the department’s website.
