A dairy worker in Yakima County, Washington, has tested positive for avian influenza A(H5N1) after occupational contact with infected cattle, the state’s first human infection tied to dairy cows, according to an October 19 update from the European Centre for Disease Prevention and Control (ECDC). The case, reported on October 15, brings the US total to 72 confirmed human infections since April 2024, ECDC said, and comes as the World Health Organization (WHO) logged one new H5N1 infection in Cambodia and four H9N2 infections in China in its latest monthly assessment of zoonotic influenza.

According to the ECDC update, the patient experienced mild illness, was not hospitalized and is isolating at home. Public health authorities have begun contact tracing and symptom monitoring of close contacts, and no evidence of sustained human-to-human transmission has been identified. Highly pathogenic avian influenza has been detected in dairy cattle in Yakima County, and local authorities are working with the affected farms.

ECDC’s tally of 72 US cases since April 1, 2024, includes one death. It breaks down as 42 infections linked to dairy cattle (36 in California, two in Michigan, and one each in Colorado, Nevada, Texas and Washington), 24 linked to poultry or culling operations (11 in Washington, nine in Colorado, and one each in Iowa, Ohio, Oregon and Wisconsin), three linked to other animals, including the fatal case in Louisiana, and three with unknown exposure. The Centers for Disease Control and Prevention (CDC), whose situation summary was updated on October 15, also counts 72 reported human A(H5) cases since February 2024, of which seven were detected through national flu surveillance and 65 through monitoring of people exposed to animals.

“While the current public health risk is low, CDC is watching the situation carefully and working with states to monitor people with animal exposures,” the agency’s page says. ECDC rates the risk from the circulating clade 2.3.4.4b viruses as low for the general population and low-to-moderate for people whose work exposes them to infected animals or contaminated environments.

The global picture

WHO’s human-animal interface assessment for September 7 to October 7 recorded one human H5N1 infection, four H9N2 infections and one infection with a swine-origin A(H1N1) variant virus. The H5N1 case was an adult man from Oddar Meanchey Province, Cambodia, who developed a runny nose on September 24 and had frequently visited a family member’s poultry farm where chickens began dying around September 13. He was admitted to hospital for isolation and oseltamivir treatment, and WHO said he is the sixth case reported in Cambodia in 2026. The four H9N2 cases in China, three of them in children under five, were mostly mild and linked to poultry or live bird markets. The A(H1N1) variant case, a woman in Santa Catarina, Brazil, with pre-existing chronic conditions, died on August 28.

WHO’s overall judgment is unchanged: the global public health risk from H5N1 is low and no sustained human-to-human transmission has been identified. “There has been no reported human-to-human transmission of A(H5N1) viruses since 2007, although there may be gaps in investigations,” the assessment says. The WHO Western Pacific office’s weekly update of October 9 puts the cumulative global count at 1,003 confirmed human H5N1 cases from 25 countries between January 2003 and September 6, 2026, of which 479 were fatal.

Why it matters

The Washington case fits the pattern that has defined the US outbreak since 2024: sporadic, mostly mild infections in people who work directly with infected cows or birds, with no onward spread detected. That is reassuring for the general public, but ECDC’s higher risk rating for exposed workers is the practical point. Dairy and poultry workers remain the people most likely to be infected, and CDC’s figures show that 65 of the 72 US cases were found through active monitoring of exposed people rather than routine flu surveillance.

For Europe, ECDC notes that there have been no confirmed human H5N1 infections and no reports of H5N1 in cattle in the EU/EEA, and that the B3.13 genotype found in US cattle and several US human cases has not been detected in Europe. WHO’s standing advice includes avoiding contact with animals that are sick or dead from unknown causes and drinking pasteurized rather than raw milk.

The caveats

ECDC and CDC count cases over slightly different periods and describe their totals as confirmed and reported cases respectively, so the two figures of 72 are not strictly interchangeable. Details of the Washington patient’s exposure, symptoms and condition come from state and local health authorities as relayed by ECDC. Genetic sequencing of the Cambodian case was not possible because of low viral load, WHO said, so the virus clade involved there is unknown.

This article is for general information and does not replace advice from a qualified clinician. Corrections: email the editor using the address on the Contact page.