Third U.S. Dairy Worker Tests Positive for Bird Flu With Respiratory Symptoms

A third dairy worker in the United States has contracted bird flu, and for the first time, the infection came with respiratory symptoms. The worker, employed at a Michigan dairy farm, developed a cough without fever along with eye discomfort and watery discharge—a departure from the two previous cases, both of which presented only as conjunctivitis, or pink eye. The worker received antiviral treatment and is isolating at home while symptoms resolve. Household contacts remain symptom-free but are being monitored.

The case arrived as Michigan confirmed its second human infection tied to the dairy cattle outbreak, which has now spread across 67 herds in nine states since March. The first human case emerged in Texas on April 1; the second appeared in Michigan on May 22. This third infection, at a different farm than the second case, underscores a pattern: dairy workers remain the primary vector for human transmission, though officials stress there is no evidence of person-to-person spread.

The Centers for Disease Control and Prevention maintains that bird flu poses a low risk to the general public. Nirav Shah, the CDC's principal deputy director, acknowledged that respiratory symptoms were not unexpected—past novel influenza viruses have featured them—but noted that coughing increases the likelihood of viral exposure compared to eye symptoms alone. Even so, infectious disease experts characterize this case as mild. Dr. Amesh Adalja of Johns Hopkins Center for Health Security emphasized that despite the respiratory component, the infection remained manageable, though it highlights the particular vulnerability of farm workers.

Michigan is now launching a testing program to screen dairy farm workers for evidence of prior bird flu infection, a move designed to map the true scope of human exposure. The state and CDC will collaborate on the effort, though details remain sparse—officials have not yet announced when testing will begin or how many workers will be included. The underlying question is urgent: Has the virus spread asymptomatically among workers, moving silently from farm to farm? Michael Osterholm, a bird flu expert at the University of Minnesota, stressed that widespread human exposure could increase the odds of the virus mutating into a form more easily transmitted between people. That remains the threshold that would genuinely alarm public health officials. For now, there is no sign of it.

The federal government is mobilizing resources on multiple fronts. The Department of Health and Human Services announced that 4.8 million doses of bird flu vaccine will be manufactured by summer. The Department of Agriculture is launching a pilot program allowing farmers to bulk-test their dairy cows' milk rather than testing individual animals before shipment across state lines—a practical measure to reduce friction in the supply chain while maintaining surveillance. The USDA is also committing an additional $824 million to work with states on bird flu testing and surveillance infrastructure.

The three human cases remain unconnected to one another, officials say, each tied independently to exposure to infected cattle. The worker with respiratory symptoms was given antiviral medication and is recovering at home. What happens next depends partly on what Michigan's testing program reveals about how many workers may have been exposed, and whether any carry evidence of prior infection. The virus itself has not changed its behavior—no human-to-human transmission has been detected—but the addition of respiratory symptoms to the clinical picture has widened the aperture through which officials must now watch.