Washington dairy herds record 27 confirmed bird flu cases in three weeks

The Washington State Department of Agriculture confirmed that 27 dairy farms in the state tested positive for highly pathogenic avian influenza between early October and Oct. 26. The agency first detected the virus in two herds in Yakima County before identifying new cases in Benton County on Oct. 26. Amber Itle, the state veterinarian, stated that the virus is moving quickly despite containment efforts.

Itle noted that the risk to humans is currently very low. She explained that milk from infected cows does not pose a risk if consumed, but the department recommends pasteurized milk because the processing heat kills the virus. The agency has not found the virus in meat products.

Researchers continue to study how the disease spreads between farms. Itle said that moving sick cattle and contaminated equipment are known causes, but other factors may contribute. She cited studies suggesting that flies, wind, and birds moving between locations can also transport the virus.

Washington is the 20th U.S. state to detect avian influenza in dairy cattle. The Washington Animal Disease Diagnostic Laboratory performed more than 7,000 tests on individual farms over the last two years. All of those tests returned negative results until the outbreak began three weeks ago.

The department is now testing every farm in the targeted milkshed where the spread is occurring on a weekly basis. Itle said this intensive monitoring is necessary to track the movement of the virus. The agency advises farmers to isolate animals showing symptoms and to report cases via email at ahealth@agr.wa.gov or by phone at (360) 902-1878.

Common symptoms of the disease include a drop in milk production, changes in how the milk looks, and a loss of appetite. Cattle may also develop fevers, respiratory problems, or changes in their manure. According to the agency, most infected cattle recover within six weeks when properly treated.