Second avian flu human case detected in Michigan farmworker

A second human case of avian influenza tied to the current outbreak of the virus among cows was announced on Wednesday by the Michigan Department of Health and Human Services.

Federal health officials emphasized the latest bird flu human infection is not unexpected and that research is ongoing to understand whether vaccine candidates and therapeutics will be effective against the virus. They said the virus' move from birds into cows and humans is worrisome due to the risk that the virus evolves to be capable of spreading among humans, but public health officials say the risk of a bird flu pandemic remains low.

The infection, found in a Michigan farmworker with "regular exposure to livestock" infected with avian influenza, follows that of a dairy worker in Texas who tested positive for avian influenza earlier this year and experienced pink eye symptoms. The CDC received the Michigan sample on Tuesday and confirmed the result that evening.

"According to the Centers for Disease Control, the risk to the public remains low; the Michigan farmworker diagnosed with influenza A (H5) had mild symptoms and has recovered," the Michigan Department of Health and Human Services said in a press release. "Information to date suggests this is a sporadic infection, with no associated ongoing spread person-to-person."

While a nasal swab from the person in Michigan tested negative for influenza, an eye swab was shipped to the CDC and tested positive for avian flu, the agency said in a statement. Similar to the Texas case, the Michigan patient only reported eye symptoms. the CDC is closely watching influenza surveillance systems, particularly in affected states, and there has been no sign of unusual influenza activity in people.

CDC Principal Deputy Director Nirav Shah said genomic-sequencing data expected to be available in the coming days should show whether the virus is susceptible to vaccine candidates and therapeutics the U.S. has stockpiled. He said it is notable that a nasal sample from the Michigan farmworker tested negative while an eye specimen tested positive.

“That’s reassuring,” Shah told reporters. “It reduces the likelihood — it does not eliminate — but it reduces the likelihood of a respiratory route of transmission. The other thing that it underscores is the importance of [personal protective equipment] barrier protection, in particular for the eyes.”

The U.S. government currently has two human virus vaccine candidates that it believes are a good match for the strain currently circulating.

HHS Assistant Secretary for Preparedness and Response Dawn O'Connell told reporters on Wednesday the government has begun to prepare approximately 4.8 million doses of vaccine expected to be well-matched against the currently circulating strain of the virus.

“We worked with our industry partners to identify a manufacturing spot that can be used to do the fill and finishing without disrupting the ongoing production of seasonal flu vaccine,” O'Connell said. “This step further strengthens our preparedness posture.”

The government has conducted testing of milk and other dairy products at the retail level, but no viable H5N1 virus was detected in pasteurized milk. Tests of retail ground beef also failed to turn up any virus.

Only one other case of avian influenza has been detected in the U.S. — in 2022, a Colorado worker who was involved with the culling of birds with suspected H5N1 bird flu tested positive for the virus and subsequently recovered.

“The overarching takeaway is that this virus remains in circulation and still presents a serious occupational hazard to people who have exposure to raw milk,” Jennifer Nuzzo, an epidemiologist and director of the Pandemic Center at the Brown University School of Public Health, said. “We haven’t done an adequate job of protecting workers who might be exposed.”

As federal officials praised Michigan’s monitoring efforts, Nuzzo noted that there’s variation across states in surveillance levels. “You only find infections you actually try and look for,” she said.

In response to the case in Michigan, USDA announced expanded financial and testing support to the dairy industry, including additional funding for dairy herds that are not currently positive for H5N1. The expanded financial assistance includes coverage for veterinary costs associated with testing for the virus. USDA is also planning to expand disaster assistance to farmers to compensate them for the cost of milk lost due to infected animals. The department has already imposed testing requirements for lactating cows moving across state lines.

The CDC has struggled to get farms and some state officials to agree to allow federal response teams onto dairy farms as the outbreak has spread across nine states and at least 51 dairy herds.

“As we see with this case and the prior one in Texas, the risk to farmworkers is elevated,” Shah said. “We'd like to be testing more people, and we've seen variable cooperation among farmworkers, as you would see with any slice of people in the general population,” he added.

And federal officials face an uphill battle when it comes to convincing farmers and farmworkers to wear the protective equipment like goggles and face shields the CDC recommends. The gear is a new cost for farms already facing tight margins — and some of it is impractical when working around 1,000-pound animals amid surging temperatures during the summer months. Still, just a handful of states have taken the CDC up on its offer for free protective gear.

Farmworker advocates have also warned that because many workers are immigrants and undocumented, they may be less likely to seek out medical care or to alert their employer to bird flu symptoms for fear of retaliation.

Chelsea Cirruzzo and Marcia Brown contributed to this report.