Bird flu landing in The City is ‘a blip on the radar,’ experts say

While San Francisco recorded its first bird flu cases of the year last month, local experts say that San Franciscans don’t need to be concerned about the disease just yet.

“It came and went,” said Dr. George Rutherford, an epidemiologist and head of the Division of Prevention Medicine and Public Health in the Department of Epidemiology and Biostatistics at UCSF. “The newer samples are negative, so it was a blip on the radar.”

In early May, two asymptomatic birds tested positive during a routine check by California Department of Food and Agriculture officials, as first reported by the San Francisco Chronicle.

As of now, “there are no reported human cases of H5N1 and H5N1 remains a low risk to the general public,” the San Francisco Department of Public Health told The Examiner on Tuesday.

According to the U.S. Centers for Disease Control and Prevention, the cases were found on May 9 in a flock of 700 birds at a live-bird market in The City. Following the positive test, those who came into contact with birds were observed for 10 days, and no positive symptoms were detected, according to the San Francisco Department of Public Health.

No members of the public were exposed, and the market has since reopened safely, according to SFDPH’s report for Tuesday’s Health Commission meeting.

While the May cases were the first in San Francisco this year, others have been reported throughout the state since January, with four in Merced and others in Sacramento, Placer and Sonoma counties.

The cases come amid a major nationwide outbreak of H5N1, known as the avian flu. This year marks the first time that the virus has jumped species into cattle, with outbreaks in nine states so far, affecting 79 dairy herds as of the latest numbers from the CDC .

The virus has also spread to humans. According to SFDPH, three dairy workers in the U.S. have so far contracted the virus from cows.

According to the WastewaterSCAN Dashboard, a national wastewater monitoring system, the virus has also been detected in San Francisco’s wastewater from the Oceanside Water Pollution Control Plant, which is located just off Ocean Beach.

In San Francisco, the virus was not detected during further testing at the end of May, according to Tuesday’s DPH report for the Health Commission meeting, and so far The City is the only municipality in the state to report a positive H5N1 detection.

“We have been working to learn more about how to interpret these findings,” the DPH report said. “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.”

City residents shouldn’t be too concerned about the presence of the virus, even if they raise chickens or other backyard fowl, Rutherford said.

“It’s probably not that big a deal if you have backyard chickens,” he said. “However, that is something to be seriously aware of if your backyard chickens start to drop dead.”

Chickens who contract the virus typically begin showing respiratory issues and other symptoms, then die suddenly , Rutherford said. Pet owners should also be careful, particularly those with cats who might enjoy hunting birds.

“It has been isolated to cats, animals that interact with birds, especially dying birds,” he said.

But there has been no transmission from cats to people, at least none that officials know of, Rutherford said. The main mammal transmission people need to be aware of now is from cows to people.

“It’s not a great leap of imagination ... that the people who work very closely with cattle, they’ve gotten infected as well,” he said. “But it’s not in the milk supply, it’s not in the meat supply, it’s not in the egg supply, it’s not in the poultry-meat supply.”

The only thing that could be an issue is unpasteurized or “raw” milk, which the California Department of Public Health advises against drinking because it might contain certain germs such as salmonella. Raw milk is available throughout the state, with 191 locations selling it in California , according to Raw Milk Finder.

But the likelihood of transmission through ingestion is also unlikely, said Rutherford. Instead, what people need to look out for is the milk itself splashing into their eyes, said Dr. Peter-Chin Hong, an infectious disease expert with UCSF.

A case was reported in March of this year of a dairy worker in Texas who suffered an eye infection caused by the virus, with symptoms of redness and irritation. Two other infections occurred in dairy workers in Michigan, with the l atest reported last week by the CDC , suffering symptoms more in line with the flu, such as a cough.

“Of the three cases in this current dairy outbreak for humans ... two were eye infections, and one was a respiratory infection,” Chin-Hong said. “We don’t have all the details of all the cases yet, but essentially, the first case in Texas was a dairy worker who likely got splashed in the eye.”

Still, the virus could evolve, he said, and people should be on the lookout for symptoms such as red eyes if they work near or with dairy cows, and they should make sure to speak with their health-care providers about their histories.