The California case is the first confirmed case of bird flu in a child in the US

Health officials on Friday confirmed bird flu in a California child — the first case reported in a minor in the US.

The child had mild symptoms, was treated with antiviral drugs and is recovering, the Centers for Disease Control and Prevention said in announcing the test results. No details about the child have been released, except that they live in Alameda County, which includes Oakland, and attend day care.

The infection brings the number of reported cases of bird flu in the U.S. this year to 55, including 29 in California, the CDC said. Most were farm workers who tested positive with mild symptoms.

One exception was an adult in Missouri who did not work on a farm and had no known contact with an infected animal. How that person became infected remains a mystery — health officials said there is no evidence it has spread between people.

A British Columbia teenager was recently hospitalized with bird flu, Canadian officials said.

H5N1 bird flu has spread widely in the US among wild birds, poultry and a number of other animals in recent years.

It began spreading to U.S. dairy cattle in March. California has become the center of that outbreak, with 402 infected flocks detected there since August. That is, 65% of the 616 confirmed with the virus in 15 states.

Officials said they are investigating how the child became infected. California health officials previously said in a statement that they are investigating a “possible exposure to wild birds.”

There is no evidence of bird flu spreading from the child to other people.

People in the child’s household reported having similar symptoms, but their test results were negative for bird flu. Health officials noted that the child and household members also tested positive for other common respiratory viruses.