Los Angeles County health officials confirmed the region's first human case of H5 bird flu last week, marking a significant development in the ongoing outbreak that had already affected several domestic cats in the area, raising concerns about the virus's spread among mammals.
The human case involved an adult who contracted the virus through exposure to infected livestock at work. The patient experienced mild symptoms and is recovering at home after receiving antiviral treatment. The case represents the first human infection in Los Angeles County, though officials emphasize there is no evidence of person-to-person transmission.
"People rarely get bird flu, but those who interact with infected livestock or wildlife have a greater risk of infection," said Dr. Muntu Davis, Los Angeles County Health Officer. "This case reminds us to take basic precautions to prevent being exposed."
Earlier in the month, health officials confirmed two cases of H5 bird flu in cats that had consumed recalled raw milk from Raw Farm, LLC. Both cats died after developing severe symptoms, including fever and neurologic signs. Three additional suspected cases in cats from a different household were under investigation, with one testing positive for Influenza A and two others presumed positive after dying from respiratory illness.
"The risk of H5 bird flu remains low in Los Angeles County, but these confirmed cases of the virus in pet cats are a reminder that consuming raw dairy and meat products can lead to severe illness in cats," said Dr. Barbara Ferrer, Director of the Los Angeles County Department of Public Health.
The outbreak has prompted increased surveillance and testing at the Public Health Laboratory, where samples from birds, cats, and wild mammals are being regularly screened for H5 bird flu. The laboratory also routinely tests clinical specimens from humans as part of ongoing monitoring efforts.
Medical experts emphasize that while the situation requires attention, the risk to the general public remains minimal. However, they warn that the virus's ability to spread among mammals is concerning.
"This is not yet a threat to everyday people who are not in close contact with affected animals, such as dairy cattle, poultry and wild birds, and we have not seen any human-to-human transmission of the virus," said Dr. Jonathan Grein, director of Hospital Epidemiology at Cedars-Sinai and head of the medical center's Special Pathogens Response Team. "We're concerned that this virus now spreads more readily across mammals—cattle in particular—and as this virus mutates and adapts, it has the potential to spread even more easily."
Health officials are monitoring close contacts of the infected person and other workers exposed at the worksite. The department has implemented preventive measures, including offering personal protective equipment, testing, and antiviral prophylaxis to those at risk.
The county has issued comprehensive guidelines for residents and workers who interact with animals. Recommendations include wearing protective equipment such as N-95 masks, goggles, and disposable gloves when working with animals, avoiding consumption of raw dairy products, and maintaining proper hygiene practices.
Public Health officials continue to advise residents to avoid consuming raw milk products, limit contact with sick or dead animals, and maintain distance from wild birds. They also recommend removing bird feeders and baths to reduce the risk of virus transmission among wild birds.
The Centers for Disease Control and Prevention and the California Department of Public Health are working closely with local officials on the ongoing investigation as authorities remain vigilant for any signs of broader transmission.
Bird Flu FAQ Courtesy of Cedars-Sinai
How is bird flu different from seasonal flu?
They’re both from the same family of influenza viruses, but H5N1 binds to different cell receptors. They both cause similar symptoms—fever, sore throat, cough, muscle aches—but conjunctivitis appears to be more common with H5N1 patients who have had close contact with dairy cattle. Both viruses can cause mild illness or more severe forms like pneumonia, but these viruses behave differently. The flu generally follows more established seasonal patterns, whereas H5N1 is more unpredictable. We largely use the same antiviral—Tamiflu—to treat H5N1 as we do to treat seasonal influenza.
How can I know which type of flu I have?
There is no way to determine which virus you’ve contracted unless you get tested. As seasonal flu activity picks up, it will be really important to understand which virus you have. From a public health perspective, we need to understand what’s happening in the community. On a personal level, you’ll want to keep those around you safe, especially if you’ve contracted something beyond the typical seasonal flu.
Will my flu shot also protect me from H5N1?
The flu shot is our most powerful tool to protect yourself and those around you from seasonal influenza. But it likely does not confer protection against bird flu. Vaccines have been developed for H5N1, but they’re not widely available at this time, although some have been stored in a strategic national stockpile to be deployed in an emergency. Drugmakers are developing additional vaccines, and their development process would likely pick up if we began seeing H5N1 spread between humans.