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For weeks now, as the H5N1 bird flu has been spreading into dairy cattle herds in more and more places, one state continues to lead the pack. With reports of infections in 25 herds, Michigan currently accounts for about one-third of the country’s confirmed cases in livestock. And of the three people known to have contracted the H5N1 virus from sick cows since the outbreak began, two of them are farmworkers in Michigan, including one who experienced respiratory symptoms.

This has led many scientists and public health officials following the situation to wonder among themselves: What exactly is going on in Michigan? But not for the reason you might think. Of the half-dozen experts STAT spoke to for this story, none believed that the virus was acting differently there, or that state policies were throwing open the door to uncontrolled spread. On the contrary, the reason Michigan has become such an apparent hotspot is because its public health response has been uniquely robust.


“We’ve tested more individuals in Michigan than any other state, to my knowledge,” Natasha Bagdasarian, the state’s chief medical executive told STAT in an interview. Bagdasarian, who was an infectious disease doctor who oversaw outbreak response in hospitals before she took up her role as Michigan’s chief medical executive, said that experience informed her current approach to the H5N1 situation. “One of our mantras is if you don’t test for it you don’t find it,” she said. “And that’s exactly what happens in a situation like this. If you don’t test for it you won’t find it.”

It’s an approach other states haven’t embraced as vigorously, and one pandemic preparedness experts hope those states learn from.

Besides Michigan, 11 other states also have dairy herds with known infections, according to the U.S. Department of Agriculture, with Idaho and Texas also reporting double-digit outbreaks. Public health authorities and scientists believe H5N1 is more widespread than those numbers would suggest, but efforts to clearly map the scale of the problem have been stymied by a lack of cooperation from dairy farmers. Outside of moving animals across state lines, testing of herds is voluntary, as is testing of anyone who’s been in close contact with infected or potentially infected animals.


Since H5N1 was first detected in Michigan dairy herds at the end of March, the state has tested 54 people as part of its efforts to monitor the health of farmworkers who’ve been exposed to infected animals. Samples from 17 of those individuals were sent on to the Centers for Disease Control and Prevention for further testing, making up more than one-third of all the tests the agency has run related to dairy herd outbreaks, according to data the CDC posted Friday.

In Idaho, which has seen a rise in dairy herd outbreaks in the last week, five people with possible exposure have been tested, and H5N1 was not detected, AJ McWhorter, a public information officer for the state’s Department of Health and Welfare, told STAT Tuesday. In Texas — where the first human case of H5N1 contracted from a dairy cow was confirmed — roughly 20 dairy workers with flu-like symptoms have volunteered to be tested, according to health officials there. No one else has tested positive.

“We’ve tried working with dairy industry groups in Texas but dairies are concerned about biosecurity and have not allowed public health on to the farms,” Lara Anton, a press officer with the Texas Department of State Health Services told STAT via email. Most of the department’s outreach has gone through cattle veterinarians instead, she said. In fact, it was a veterinarian working with several Texas Panhandle dairies who brought the dairy worker who tested positive to the department’s attention.

“Michigan is looking more closely than a lot of other states,” said Lauren Sauer, who directs pandemic preparedness research at the University of Nebraska Medical Center’s Global Center for Health Security. “They’re doing more surveillance in humans and animals so they’re finding more cases in humans and in animals. That tells me that we’re only finding things where we’re looking, and that’s not where we want to be.”

Pandemic playbook authors like Sauer have long been preparing for almost exactly this scenario — an H5N1 bird flu strain makes its way into a population of animals that have a lot of contact with humans and then some of those humans get sick. Without broad testing to provide adequate visibility into that human-animal interface, we risk missing the next step in a pathogen’s path to pandemic potential: evolving to more easily transmit between people.

What the playbooks didn’t account for though, is that the human-animal interface could be a milking parlor. Up until this year, instances of influenza in adult dairy cows were rare, which is one reason the outbreak went undetected for months before H5N1 was identified as the culprit. Poultry and pork operations, in contrast, have been dealing with the risks of avian influenza for a long time, and have established regulations and surveillance systems in place to quickly curb further viral spread.

“The dairy industry has never had to deal with anything like this before,” said Keith Poulsen, director of the Wisconsin Veterinary Diagnostic Laboratory and a former dairy cattle veterinarian. “And I think we’ve learned that voluntary testing isn’t going to work. It’s not working now. Other than a few people here and there, it’s not being taken up.”

Sauer’s group is hoping to learn more about how Michigan’s state and local authorities made inroads into the dairy industry, which in many other parts of the country has been slow to accept personal protective equipment and resisted testing of animals and farmworkers. “It’s clear to me that whatever they’re doing is working. If we can get a better sense of what they’re doing to create this openness, that will be good for all the states.”

Three years ago, Kim Dodd packed up her office at the U.S. government’s most secure laboratory for research on potentially deadly agricultural illnesses and headed to Michigan, to direct the Michigan State University Veterinary Diagnostic Laboratory. At the federal lab, she had overseen the development of diagnostics and other countermeasures against pathogens common overseas but not often seen in the U.S.

“I had a chance to get an understanding of a lot of different state dynamics,” she told STAT in an interview. “And Michigan, in my experience, is truly unique.”

Dodd arrived to find a state government with highly collaborative relationships between animal health, human health, and environmental agencies honed over decades of dealing with overlapping threats, including chronic wasting disease, bovine tuberculosis, and cancer-causing chemicals that got into Michigan’s food supply in the 1970s through contaminated animal feed. Leaders from these agencies meet monthly to discuss any emerging pathogens and regularly drill pandemic preparedness exercises.

When H5N1 began reappearing in the state’s poultry flocks in March and April, Dodd expanded the number of laboratory staff who were certified to run tests for the bird flu and switched the lab over to testing seven days a week. The idea was to build enough bandwidth to deal with surges, even during times of the year when staff tend to be out sick. She had no idea that capacity would be called upon almost immediately, as the virus began infecting the state’s dairy cows. But it proved to be a critical piece of the state’s emergency response.

As Dodd’s veterinary diagnostic lab detected more positive cases, from both dairy farms and poultry operations, it sent those samples to a national USDA lab for genomic sequencing. Analyses of those sequences revealed that at least some of the new infections detected in Michigan’s poultry farms had been seeded by outbreaks at nearby dairies. Since cows don’t often walk off of their farm and into a poultry barn, the virus had to be traveling some other way. Vehicles and people moving between farms seemed a much more likely culprit.

That was a big reason why on May 1, Tim Boring, director of the state Department of Agriculture and Rural Development, declared an “extraordinary animal health emergency,” signing an order requiring Michigan dairy farmers to ramp up biosecurity on farms. The move was and remains an unusually stringent one.

“Michigan was a little different because they immediately required enhanced biosecurity measures,” Poulsen said. “But they have always been a little bit more proactive because of their experience with other diseases.”

Poulsen and others noted that the state has also stood out in the way it has reported cases to the public. While the USDA has reported dairy herd outbreaks of H5N1 only at the state level, and most other states have followed that lead, Michigan reports the counties in which any new infections have been detected. The state agriculture agency set up an email alert system so people can sign up to receive notifications of any new outbreaks.

“It offers a level of specificity of where this virus is being detected around the state that I think is really helpful to heighten the awareness that this is happening in specific communities,” said Boring. “And it walks this line of making sure we’re not divulging individual farm information.”

That’s important because the laws that govern animal health in Michigan contain a confidentiality provision that prevents releasing the identity of the owner of a sick animal and any information gathered in connection with investigating the illness. People in the state agriculture department jokingly refer to it as “Animal HIPAA.”

“It’s an outlier and a rarity,” said Brook Duer, a staff attorney at Penn State’s Center for Agricultural and Shale Law.

More common is for state regulatory agencies that oversee animal health to have broad authority to use information gathered in disease investigations in whatever way best protects public health, Duer said. But that might actually make farmers less willing to cooperate, because they can’t be sure how the information they provide will be used.

“One of the challenges with this outbreak is that procedures for testing and how to report data are being left up to individual states to figure out,” said Andrew Pekosz, an influenza researcher and director of the Center for Emerging Viruses and Infectious Diseases at Johns Hopkins University. “Each state has different regulations for how they can collect and share data, which means it can be difficult to compare one state’s response to another. But Michigan has found a very efficient way to not only engage dairy farmers in the testing process but also been fairly open in terms of sharing those results with the general public.”

That transparency extends to efforts the state is making to find infections in people. Local public health officials in affected counties have been following up with farmworkers via phone calls and text messages to actively monitor for flu-like symptoms as well as conjunctivitis, or pink eye, and offer free testing if symptoms start to show up. In other states, dairy workers have been advised to monitor themselves and contact their health care providers and local public health districts if they become ill.

“Michigan has really been ahead of this in terms of our communication,” Bagdasarian said. “The goals for this amount of transparency are two-fold. Number one, we believe the public deserves to know. Transparency is the first step to continuing to have public trust and continuing to have people work with us. The second part is we’re hoping that other states will follow our lead. Because without having a good understanding of impact — numbers of cases and transmission dynamics — we won’t be able to fully mitigate this.”

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