Oregon reports its first H5N1 infection in dairy cows, while a U.S. farming union claims human cases of avian flu among Washington state ranch workers are underreported.

What it means

Oregon has confirmed its first infection of H5N1 bird flu in a dairy cow herd, expanding the geographic footprint of the ongoing US livestock outbreak. Separately, the United Farm Workers union is alleging that human H5N1 cases among agricultural workers in Washington state are being underreported by official channels, raising concerns about the true extent of animal-to-human spillover.

Accuracy & sourcesGrounded

The Oregon cow case is a solid claim backed by an official state agriculture department confirmation. The underreporting claim is an allegation from the United Farm Workers union, reported accurately as their position, but it is not an independently verified epidemiological finding. The reporting (Phys.org, CIDRAP) sits very close to these primary sources.

How new

Genuinely new: the Oregon dairy herd infection is a first for that state, and the union's underreporting claim is a fresh development in the ongoing US H5N1 outbreak, reported in November 2026.

Go deeper

• Phys.org — first to publish