Idaho has emerged as the most active state in the country for highly pathogenic avian influenza in livestock, recording 40 confirmed cases in dairy herds during the 30 days ending June 29 — dwarfing activity in every other state combined over that same period.
Idaho Far Outpacing Other States
During the week of June 22–28 alone, eight new dairy herd infections were confirmed in Idaho. That same week, a poultry operation in Canyon County reported roughly 3,000 affected birds — a case officials believe was triggered by exposure from a neighboring dairy farm. In the same 30-day stretch, only five cases were confirmed elsewhere in the nation: three in Utah and two in Texas.
Idaho State Veterinarian Scott Leibsle said the situation is accelerating. “It’s just surging now,” he said.
Idaho has now recorded 172 affected herds since the outbreak began affecting cattle in 2024, with all but one located on dairy milking cow premises. That makes Idaho the current national leader by a wide margin. California, the only other state with comparable totals, logged 773 cases but has not reported a new livestock herd infection since November. Oregon has had a single case at a backyard operation. Washington has recorded none.
Across the entire country, federal data shows 1,154 total incidents in livestock herds spanning 20 states, with cattle accounting for all but two of those incidents. You can read more about Idaho’s surge in H5N1 dairy cases and the quarantine situation as the outbreak has developed over the past year.
How the Strain Is Spreading
Unlike earlier phases of the bird flu outbreak, the strain circulating in Idaho dairy herds is spreading through bovine-to-bovine contact rather than from wild bird populations. That distinction matters for how producers and regulators approach containment strategies.
Infected cows are placed under quarantine but are not removed from milk production. Officials note that pasteurized milk from infected animals does not pose a human health concern, and cattle that contract the disease generally recover and resume normal production.
What Idaho Is Planning Next
State officials are weighing early intervention measures ahead of next spring, when herd movement and calving activity could create new transmission opportunities. Idaho is considering aggressive surveillance and sampling beginning in March to get ahead of seasonal spread.
Leibsle also indicated openness to emerging tools, including a potential vaccine. “If there is a vaccine in development, we would certainly be open to trying it out,” he said.
Stakes for Idaho Agriculture
Idaho’s dairy industry is one of the largest in the nation, and the concentration of cases in milking cow operations makes the ongoing outbreak a significant concern for producers across the state. The Canyon County poultry case underscores that the disease can jump from dairy herds to nearby poultry operations, broadening the potential agricultural impact.
With national case counts heavily weighted toward Idaho and the rest of the country seeing only scattered activity, state officials and producers will be watching closely whether the planned March surveillance program can slow the trajectory before another active season begins.