Pandemic potential? What to know in Florida about bird flu outbreak.

Even as we grapple with how COVID-19 has changed everything, experts are concerned that a variant of influenza spreading in the U.S. could spark another global outbreak of illness — shuttering restaurants, offices and schools once more.

H5N1, a bird flu virus, is infecting dairy cows, alarming researchers as it inches closer to humans.

While cases are rising, with over 100 herds affected nationwide, scientists worry that not enough testing is being done to understand the outbreak’s full scope. Florida has yet to record a case in cows. Michigan has reported the most of any state, with infections logged in 25 herds.

“Nobody wants a pandemic,” said Seema Lakdawala, a professor in the department of microbiology and immunology at Emory University. “And the more chances we give this virus, the more shots on goal it takes, the more likely we are to be in a scenario where we have H5 circulating in the human population.”

Here’s what Floridians should know.

What is H5N1?

H5N1 is a type of influenza A. Some influenza A viruses cause the seasonal flu in humans, while others cause bird flu. First detected in farmed geese in China in 1996, H5N1 has occasionally infected humans. From 2003 to 2019, about 860 people contracted the virus, which is more contagious in birds than people, according to global data from the World Health Organization. Egypt, Indonesia and Vietnam accounted for 8 out of 10 cases during this period.

A highly virulent form of H5N1 was identified in Europe four years ago, spreading to Africa, the Middle East and Asia. It resulted from wild bird and poultry flu viruses exchanging genetic material. It reached North America in late 2021.

H5N1 has devastated the animal kingdom. In 2022 alone, more than 131 million poultry died from the illness or were slaughtered in attempts to contain the virus, according to case data from 67 countries. The virus has infected mammals, too, including bobcats, raccoons, red foxes and a dolphin in Florida, which died. Seals and sea lions have been hit hard, with tens of thousands killed.

Beginning in late March, U.S. agriculture officials began to report infections in dairy cattle — a startling development that is raising concerns among scientists. Cases as of Tuesday have been detected in 101 herds from Colorado, Idaho, Iowa, Kansas, Michigan, Minnesota, New Mexico, North Carolina, Ohio, South Dakota, Texas and Wyoming.

Researchers believe the virus jumped from wild birds to cows in the Texas Panhandle sometime in December, then spread silently for months.

Have there been cases in Florida?

Not in cows, according to data as of Tuesday from the U.S. Department of Agriculture.

But more than 500 wild birds across the state have been diagnosed with the illness since 2022, according to the federal agency. That’s likely an undercount because many birds die and aren’t found. H5N1 has reached Tampa Bay counties, infecting vultures, great horned owls and bald eagles, according to data from the department. A spokesperson for the St. Petersburg-based Fish and Wildlife Research Institute previously said the state had “likely lost tens of thousands” of native birds.

Is the state testing cattle?

Yes. As of early last week, the Florida Department of Agriculture and Consumer Services had tested 65 dairy cows for bird flu. Five of the animals — from three separate sites in Alachua, Gilchrist and Suwannee counties — were tested because they exhibited symptoms “that could be associated with H5N1.” All were negative, according to the department.

The remaining 60 cows were tested prior to movement across state lines. Federal agriculture officials in late April required that lactating dairy cattle receive a negative influenza A test before interstate transport, though healthy animals headed directly to slaughterhouses are exempt.

The state agriculture agency, for now, is not conducting random testing of dairy cows, spokesperson Aaron Keller said in an email.

Agriculture Commissioner Wilton Simpson issued emergency restrictions in mid-April that prohibit dairy cattle exposed to H5N1 from being imported into Florida.

There are about 125,000 dairy cows in Florida, which collectively produce about 300 million gallons of milk per year, according to Florida Dairy Farmers, a milk promotion group.

How is the virus moving between cattle?

The leading hypothesis is that contaminated milk equipment is spreading H5N1 from cow to cow, said Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security.

The virus is often not in cow respiratory tracts, he said. It’s mostly concentrated in their milk.

The main sign of infection is a decrease in milk production, he added. It’s unclear if dairy cows without symptoms can still spread infectious virus.

Are people getting infected?

Unlike with COVID-19 or other viruses such as the seasonal flu, H5N1 is not rapidly spreading person to person. The risk remains low for the public, according to the U.S. Centers for Disease Control and Prevention, which has not seen an unusual uptick in emergency room visits for influenza.

But three humans in the U.S. have been diagnosed with the ailment during the dairy cow outbreak. All were farmworkers from Michigan and Texas exposed to infected cattle.

What are the symptoms?

The first two human cases tied to dairy cows contracted mild infections in the eye, possibly via contaminated milk splashing them. They reported conjunctivitis, or “pink eye.”

But the third person, a worker in Michigan, had respiratory symptoms, including a cough without a fever, that are more typical with influenza. The patient was given an antiviral drug and the infection eased while they isolated at home.

Internationally, there have been more severe outcomes with H5N1. In 2022, an adult in China died in a case linked to poultry. A 53-year-old man in Chile with a cough and sore throat was admitted to an intensive care unit last year after his condition worsened. Cambodia reported two infections in February 2023, including an 11-year-old girl who developed pneumonia and died, but testing found that the virus was different from the version sickening birds in the U.S.

Why are experts so worried?

The chief concern is that H5N1 will acquire mutations as it spreads in cows that allow it to transmit quickly among humans, spawning a pandemic. That could be catastrophic.

From 2003 to 2019, when an older form of H5N1 circulated, about half of infected people died, according to World Health Organization data. Mild cases may have been missed, inflating the death rate.

But public health experts have long feared that avian influenza might upend life as we know it — again. The 1918 flu pandemic, which killed an estimated 50 million people worldwide, is believed to have started in a bird host.

“Any time a virus that normally circulates in avian species is infecting mammals, it’s getting a chance to get more adapted to mammals,” said Adalja of the Johns Hopkins Center for Health Security.

He added that the U.S. is still “partly blind” with H5N1. There has been “very constrained” testing of cows and humans, he said. Some farmers have reportedly been hesitant to pursue testing because of the potential financial fallout of identifying H5N1 in a herd.

“We don’t understand how big of a problem this is,” Adalja said of the outbreak.

And despite the testing requirement for some dairy cows moving across state borders, there’s no equivalent federal mandate for those being transported within a state. Lakdawala, of Emory University, said whether to require testing of cattle that don’t leave is up to state officials to decide.

When asked if Florida will order testing of herds moved within the state, Keller, the Florida agriculture department spokesperson, didn’t immediately provide a comment.

Is milk safe to drink?

In a survey of almost 300 dairy product samples, a fifth contained fragments of the virus, according to an early analysis by the U.S. Food and Drug Administration. The samples were collected at stores in 17 states and included milk, cottage cheese, sour cream and yogurt. The findings suggested that many more cows were carrying H5N1 than were officially reported in federal case counts.

The agency conducted further testing to see if the virus was still infectious in the products. It wasn’t.

Pasteurization, a heating process that kills harmful pathogens, neutralizes the virus, the federal agency says.

The Food and Drug Administration in a statement to the Tampa Bay Times said “the totality of evidence continues to indicate that the commercial milk supply is safe.”

Should consumers avoid raw milk?

Yes, health experts say. It remains unclear whether drinking raw milk with H5N1 will result in an infection. But federal food regulators have long warned that consuming such products is risky because they can harbor dangerous microorganisms.

There are troubling signs that H5N1 in raw milk could cause illness. A study of mice found that they quickly exhibited lethargy after being given raw milk contaminated with the virus.

When the mice were euthanized, scientists discovered high levels of the pathogen in their respiratory organs.

Florida bars the sale of raw milk for human consumption. But raw milk labeled as pet food is found throughout the state, according to a website that tracks availability.

“Absolutely do not consume raw milk products,” Lakdawala said.

What about beef?

Federal agriculture officials say they’re confident the meat supply is safe and that they didn’t find the virus in 30 samples of ground beef collected from states where dairy cows tested positive.

In an experiment, federal Department of Agriculture researchers found that cooking hamburgers to 145 degrees (medium) and 160 degrees (well done) would kill the virus.

Is there a vaccine?

It’s a bit complicated. The bottom line: you can’t walk into Walgreens or CVS this week and get a shot to ward off H5N1.

But the Centers for Disease Control and Prevention has bird flu viruses that can be used by manufacturers to develop a vaccine, with good protection against H5N1 expected.

The problem is one of logistics. If a pandemic were to begin, providing enough vaccines would be challenging.

How else can individuals, and pets, stay safe?

Avoid sick or dead animals, including wild birds and poultry, if you don’t have eye or respiratory protection, according to the Centers for Disease Control and Prevention. Stay clear of feces from critters.

Those who come into contact with sickened animals should monitor themselves for symptoms, including pink eye, for 10 days.

Keep your pets, such as cats and dogs, away from sick or dead wild birds, feathers and droppings and feed and water bowls that wild birds may have touched.

What’s going on with wastewater tracking?

Scientists have started to monitor sewage to see where H5N1 is spreading — just like with COVID-19. WastewaterSCAN, a national surveillance network from Stanford and Emory universities, recently began to test for the H5 influenza A subtype at 194 locations across the country, including 13 in Florida.

There are many H5 bird flu viruses. But if H5 is detected this summer in a treatment plant’s wastewater, it’s likely H5N1, said Alessandro Zulli, a postdoctoral scholar at Stanford who works with WastewaterSCAN.

The research team has yet to find H5 in Florida wastewater, including at three St. Petersburg facilities, according to recent data. But the virus has been identified in sewage from states like Michigan and Texas.

Detecting H5 doesn’t confirm that humans are infected, Zulli said. The virus could be entering wastewater systems through milk discharges at dairies, he said. Federal health authorities have urged farmers to throw out milk from sick cows.

Monitoring sewage is a “very early warning system,” Zulli said.

“It’s much easier to do than testing every cow in a 50-mile radius,” he said. “Or testing every person in a 50-mile radius.”