As the H5N1 bird flu spreads among California dairy herds and southward migrating birds, health officials announced Friday that there are six more cases of human infection: five in California and one in Oregon — the first in the state.

A seventh suspected case in California is awaiting confirmation from the U.S. Centers for Disease Control and Prevention.

All 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 the number of cases, it was an artifact of the state’s reporting deadlines. Three cases had been confirmed by the CDC on Wednesday after California’s reporting deadline. The other two were confirmed Thursday — a day when California does not report case counts.

And Monday was also a holiday, which further delayed reporting.

“I would still call these sporadic animals human infections, and there is still no evidence of human infection,” she said. “These are all workers who are at risk of exposure based on their exposure at work.”

In the Oregon case, the person contracted the disease as a result of a previously reported outbreak from an infected commercial poultry farm 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 made a full recovery and was being treated with oseltamivir, an antiviral drug. The health department also prescribed the antiviral medication to people who lived in the same house as the patient.

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

In addition, a teenager in British Columbia was infected from 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. They had all been in contact with infected dairy cows.

WastewaterScan – an infectious disease monitoring network led by researchers from Stanford University and Emory University, with laboratory support from Verily, the life sciences organization of Alphabet Inc. – tracks 28 wastewater sites 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 come from unpasteurized milk, wild bird feces or discarded contaminated animal products.

Cities and municipalities that have identified 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.