By Dani Blum
California has announced a state of emergency in response to an outbreak of avian influenza affecting dairy cows.
The H5N1 virus, responsible for bird flu, has been detected in 645 dairy operations in California since August. Additionally, infected herds have been found in 15 other states. Here’s what we currently understand, and what remains unclear, regarding the potential human health risks.
Should I be concerned about bird flu at this time?
California’s Gov. Gavin Newsom stated that this declaration aims to provide governmental bodies with the necessary resources and flexibility to effectively respond to the outbreak.
The Centers for Disease Control and Prevention emphasized on Dec. 18 that the H5N1 bird flu presents a low risk to public health as a whole. Michael Osterholm, an expert on infectious diseases at the University of Minnesota, concurred with this evaluation. He highlighted that the principal issue in California is the swift dissemination of the virus across dairy farms.
However, certain individuals face a greater risk of infection due to their proximity to animals that harbor the virus. Those who work directly with animals, such as dairy farm laborers, are particularly at risk and should utilize personal protective equipment including masks, gloves, and safety goggles, advised Stacey L. Schultz-Cherry, a virus and influenza specialist at St. Jude Children’s Research Hospital.
This year, there have been 61 reported cases of bird flu in the United States, with 37 cases linked to contact with infected cattle. The majority of these individuals have experienced mild symptoms, such as conjunctivitis, fever, and muscle pain.
On Dec. 18, the CDC identified the first serious case of H5N1 bird flu in the nation: a patient in Louisiana who was hospitalized following exposure to backyard poultry. The individual contracted a strain of the virus found in birds, as opposed to the variant currently circulating in cows.
For those maintaining a backyard flock, it is advisable to minimize their interaction with wild birds, stated Dr. Meghan Davis, a veterinarian and environmental epidemiologist at the Johns Hopkins Bloomberg School of Public Health. She also highlighted the necessity of keeping pets, particularly felines, away from wild birds as some cats have contracted bird flu and perished.
“If you’re not directly handling animals at the moment, I wouldn’t prioritize this as a major concern,” remarked Dr. Gail Hansen, a veterinary public health consultant based in Washington, D.C. “Currently, it’s improbable that this will pose an issue for the majority of people.”
Is the virus transmitting among humans?
To date, there is no evidence indicating that the virus can spread from person to person. Nevertheless, each time it infects a new individual or animal, it has the chance to mutate, prompting scientists to monitor closely for changes that might enhance human-to-human transmission.
“I’ve been vigilant about this virus for many years,” Osterholm remarked. It remains crucial to keep track of the virus and prepare for the possibility of it spreading among people, he noted.
Researchers are particularly worried about the virus mutating during flu season and have urged individuals to receive flu vaccinations to lessen the chances of contracting seasonal influenza.
“Our greatest concern is that an unsuitable human, bird, or animal could become infected with both a human seasonal strain and one of the bird viruses, enabling them to genetically exchange components,” Schultz-Cherry explained.
What about the milk supply?
Health officials have assured that pasteurized milk is safe for consumption. However, there are concerns regarding the risks posed by raw milk, particularly in California, where two raw-milk producers have issued recalls after bird flu was discovered in retail samples.
The U.S. Department of Agriculture has intensified its testing of raw milk in an effort to understand the extent of the outbreak.
No confirmed human cases have arisen from raw milk consumption. Nonetheless, researchers suspect that farmworkers may have contracted bird flu after encountering droplets of raw milk.
“This could potentially become an issue — don’t disregard it entirely,” cautioned Matthew Moore, an associate professor in the food science department at the University of Massachusetts, Amherst. “However, at this point, there’s no need for alarm or action beyond avoiding raw milk products.”
