After years without an outbreak, bird flu has started to move through the United States with more than 12 million cases of infection, and it may return seasonally moving forward.  

“I would suspect that we’ll probably see more seasonal incursions of H5N1 [bird flu] moving forward. At what level though, it’s hard to say,” said UF’s Dr. Benjamin Anderson. 

Anderson works as an assistant professor within the College of Public Health and Health Professions’ department of environmental and global health. Unlike seasonal flu that runs through humans, he said this strain of influenza—H5N1 or bird flu—largely rises and falls on the migratory routes of wild birds, especially waterfowl.  

Anderson said this strain produces a unique epidemiological situation that draws health professionals’ attention. 

“There are other strains of influenza that infect birds, but this one is a particular concern given that it has some unique epidemiology of transmission across different species of animals and the impact that it has on those different species varies,” Anderson said in an interview.    

Wild birds have no symptoms when infected, Anderson said, but once the virus hits domesticated poultry, symptoms appear and can be severe.  

The Florida Fish and Wildlife Conservation Commission (FWC) reported cases in 37 of Florida’s counties, including a dead dolphin that tested positive. The commission said in the spring that Florida ranked first in the nation for the number of wild birds tested with the virus.  

Anderson said has also had an aggressive tracking campaign, likely adding to the numbers compared with some other states. But, Florida also sits on a migratory route for wild birds, and most of the outbreaks of bird flu tracked in the last two years have popped up close to those routes.  

Bird flu is seasonal in many countries, but the United States saw no outbreaks between 2016 and 2021. Even now, Anderson said the risk remains low, but researchers are vigilant for changes in the virus.  

“So, we have to pay really close attention and monitor those pathways, those migratory bird pathways, so that we can get an understanding of what’s been circulated where and determine if there’s any risk of potential changes of the virus,” Anderson said. 

Changes in the virus could impact other animals or humans.  

So far, there’s only been one documented human case of H5N1 in the U.S. Anderson said that person worked in the poultry industry and handled birds infected with the virus. Worldwide, more cases have been documented, with two cases resulting in deaths reported from Cambodia in October. 

The risk remains even lower for people outside the poultry industry. But, Anderson said that as an epidemiologist he’s more concerned about small home flocks of chickens instead of a commercial-scale operation.  

He said the commercial side is regulated and has biosecurity that limits spread or mutations.  

Anderson said for poultry owners to be wary of a death without an apparent reason. He said deaths like these should be reported to the FWC who will come and run a check. He said owners should also be aware of any mixing their flock has with wild birds.  

Since the surge in the U.S. started recently, Anderson said there’s not a lot of data for predictions. He said the state and federal responses have been well-coordinated to prevent spread once an outbreak is detected.  

“As epidemiologist, we are very conscious of continuing to monitor it very closely and making sure that we are capturing data so we can see if there’s any changes in the virus that we can catch that early so that we can make better assessments as to what that risk might be down the road,” Anderson said. 

For more information, you can visit the FWC page about bird flu or check out the Center for Disease Control’s webpage.