Bird flu has now spread to humans in a dozen states after public health officials confirmed an Ohio man had contracted the disease.
The Mercer County farmworker had come into contact with deceased commercial poultry, the Ohio Department of Health announced Feb. 12. Prior to this latest case, 68 people in 11 states had been infected with an H5 strain of avian influenza, according to the Centers for Disease Control and Prevention (CDC). One person in Louisiana who had been exposed to wild birds and a noncommercial backyard flock has died, a loss the CDC called “tragic” but “not unexpected because of the known potential for infection with these viruses to cause severe illness and death.”
Most human infections in the U.S., 36, have been among people in California exposed to dairy cattle herds. Since March 2024, nearly 1,000 cattle in 16 states have tested positive for bird flu, primarily in California, according to the Department of Agriculture’s Animal and Plant Health Inspection Service (APHIS). And since February 2022, nearly 159 million birds in more than 1,500 commercial and backyard flocks have been infected, with the plurality of flocks in Minnesota.
In the past 30 days, however, Ohio has been a hotspot of poultry infections. The Buckeye State has reported more than 10.3 million sick birds, nearly half of the 24.3 million infections reported nationwide in that time frame. Such numbers were alarming to state leaders even before bird flu had spread to one of their own. U.S. Rep. Marcy Kaptur, D-Ohio, brought her concerns to the House floor.
“My state of Ohio is the second-largest egg-producing state in our nation, and nationwide over 14 million egg-laying birds have been killed since December of last year due to the growing bird flu outbreak,” Kaptur said in a congressional recording posted to X on Feb. 7. “That is why the cost of eggs [is] skyrocketing, and this is why we must get this outbreak under control as human infection rates rise.”
View this interactive chart on Fortune.com
Should I be worried about bird flu?
Yes and no. People most at risk of contracting the illness are those who work with or are otherwise likely to come into close contact with infected animals. No person-to-person spread has been detected to date, and the CDC maintains that the risk to public health is low. Consuming only pasteurized dairy products and steering clear of raw meat and poultry can help mitigate disease spread.
Still, the rapidly evolving situation calls for vigilance, says Meghan Frost Davis, DVM, PhD, an associate professor in the environmental health and engineering department at the Johns Hopkins Bloomberg School of Public Health. This is especially true now that in addition to H5N1 bird flu, which has been at the center of the current outbreak, H5N9 has been detected.
“Consumers should be on alert. Public health practitioners should be very concerned,” Davis, who is also a former dairy veterinarian, tells Fortune. “Anytime you get an additional strain of a zoonotic virus that has pandemic potential, [it] should garner caution.”
Influenza viruses are malleable such that different strains can mix and match, so to speak, Davis explains. It’s not out of the realm of possibility that a resulting recombinant bird flu virus could lead to person-to-person spread. Pigs, which can catch both bird and human flu viruses, not to mention swine flu, pose a particular threat.
“We’re always concerned about pigs getting an avian influenza,” Davis says. “That could lead to a new virus that we’ve never seen.”
As fears of mutated avian influenza spiral, H5N1 continues to surprise. In January, APHIS confirmed that an H5N1 variant not previously seen in cows had been detected in dairy cattle in Nevada.
“We have never been closer to a pandemic from this virus,” Rick Bright, an immunologist and former federal health official, previously told Fortune’s Carolyn Barber. “And we still are not doing everything possible to prevent it or reduce the impact if it hits.”
Is there a bird flu vaccine?
No, but it’s in the works. Last month, the Department of Health and Human Services granted Moderna $590 million to help accelerate bird flu vaccine development. In addition, the CDC has already prepared what it calls candidate vaccine viruses for bird flu that other pharmaceutical companies can use to develop immunizations.
In the meantime, the CDC encourages everyone 6 months and older to get their 2024–25 seasonal flu shot. This vaccine won’t protect you from bird flu, but the more people who are vaccinated, the lower the odds that a mutated bird flu virus capable of person-to-person spread will form.
For more on bird flu:
- Can you get bird flu from eating eggs? What you need to know about staying safe
- As bird flu becomes a growing threat, Moderna is awarded $590M to develop mRNA pandemic influenza vaccines
- Bird flu FAQ: Everything you need to know about the latest H5N1 outbreak
- Bird flu could merge with seasonal flu to make mutated virus that could spread among humans, CDC warns
- What are the symptoms of bird flu, and how does it spread?
