H5N1 bird flu infects six more people in California, Oregon

As H5N1 bird flu spreads among California’s dairy herds and southbound migratory birds, health officials announced Friday six more human cases of infection: five in California and one in Oregon — the state’s first.

A seventh supposed California case pending confirmation from the US Centers for Disease Control and Prevention.

All of the reported cases have been described as mild, and each person is believed to have contracted the disease from infected livestock or poultry. In California, the infections occurred among dairy workers. In Oregon, the patient was a poultry worker.

California’s state epidemiologist, Erica Pan, said that while the announcement of five cases today may sound like a sudden explosion or acceleration in cases, it was an artifact of state reporting deadlines. Three cases had been confirmed by the CDC Wednesday after California’s reporting deadline. The other two were confirmed Thursday — a day when California does not report case counts.

And there was also a holiday on Monday, which further slowed down reporting.

“I would still call these sporadic animal or human infections, and there is still no evidence of any human to human,” she said. “These are all workers who are at risk of exposure based on their occupational exposure.”

In the Oregon casethe person contracted the disease from a previously reported infected commercial poultry farm outbreak in Clackamas County. A statement from the Oregon Health Authority said there is “no evidence of person-to-person transmission and the risk to the public is low.”

The agency said the person has fully recovered and was treated with oseltamivir, an antiviral medication. The Danish Health Authority also prescribed the antiviral medication to people who lived in the same home as the patient.

Since March, the US Centers for Disease Control and Prevention said 52 people have been infected with the H5N1 virus. Dairy cattle were the source of 30 of these cases, poultry for 21. The source of another case in Missouri is still unknown.

In addition, a teenager in British Columbia was infected by an unknown source and was hospitalized in critical condition as of Friday.

Twenty-six cases have been identified in California, including the five most recent. All had been in contact with infected dairy cows.

WastewaterScan — an infectious disease surveillance network led by researchers from Stanford University and Emory University, with laboratory support from Verily, Alphabet Inc.’s life sciences arm — is monitoring 28 wastewater facilities in California. All but seven have detectable amounts of H5. It’s unclear what the source is in each system, but experts say it could be from unpasteurized milk, wild bird droppings or discarded contaminated animal products.

Cities and municipalities that have detected the virus since early November are: Gilroy, Indio, Lompoc, Los Angeles County, Los Angeles, Marina, Merced, Napa, San Francisco, Ontario, Palo Alto, Redwood City, Riverside, Sacramento, San Diego, San Jose, Santa Cruz, Southeast San Francisco, Sunnyvale, Turlock and Vallejo.