Two chickens tested positive for bird flu at San Francisco live bird market

Health officials said Monday that the H5N1 avian flu was detected last month in two asymptomatic chickens at a live bird market in San Francisco, but there is no sign that the public has been exposed.

The bird flu virus was found as part of routine tests at live bird markets around the state by the California Department of Food and Agriculture. 

Market employees who had been in close contact with the birds were monitored and didn’t report any symptoms after a 10-day period, said San Francisco Director of Health Dr. Grant Colfax in a report that appears on Tuesday’s health commission agenda.

No members of the public were exposed and the market has since reopened.

“At this time, there are no reported human cases of H5N1 and H5N1 remains a low risk to the general public,” the department said in a statement on Monday.

After the virus was detected in chickens, WastewaterSCAN, a national collaborative that monitors infectious diseases in municipal wastewater systems, found fragments of H5N1 genetic material in the city’s wastewater. Another test found no fragments, and the health department is investigating to learn more about interpreting the findings..

“It is possible that the H5N1 fragments detected in wastewater originated from birds or other animals due to San Francisco’s unique combined sewer system that collects and treats both wastewater and stormwater in the same network of pipes,” according to the report from the health department. 

San Francisco is the only city in California thus far with a positive H5N1 detection. 

The Centers for Disease Control is closely monitoring avian influenza H5N1, including recent outbreaks in dairy cattle and a single instance to date of spread from cattle to a dairy worker in Texas reported on April 1, 2024.

The public should avoid touching all wild animals, including sick or dead birds, and to continue taking protective measures such as only consuming milk or dairy products that have been pasteurized. 

“There is currently no evidence that the H5N1 virus is spreading person to person, but that is what the CDC is closely watching and working to prevent,” according to the health department. “At this time, it appears that the potential for avian flu to spark an outbreak in people remains low.”