A child in California is recovering at home from a confirmed case of bird flu. They are the first child in the United States to test positive for avian influenza, according to the US Centers for Disease Control and Prevention.

The child, who lives in Alameda County, had mild upper respiratory symptoms and was treated with flu antiviral medications, according to the California Department of Public Health and the CDC.

The child initially tested positive with low levels of virus, the health department said, and then tested negative four days later. They also tested positive for other respiratory viruses that could have contributed to cold and flu symptoms.

It’s not clear how the child was infected, but health officials are investigating a possible exposure to wild birds, the health department said in a news release.

The risk to the public is low, the health department said.

“It’s natural for people to be concerned, and we want to reinforce for parents, caregivers and families that based on the information and data we have, we don’t think the child was infectious – and no human-to-human spread of bird flu has been documented in any country for more than 15 years,” said Dr. Tomás Aragón, director of the California Department of Public Health and state public health officer.

Other members of the child’s family reported symptoms, but none tested positive for bird flu, according to the CDC. Some of the relatives tested positive for other common respiratory illnesses.

Bird flu symptoms in humans can include eye redness or discharge, cough, sore throat, runny or stuffy nose, diarrhea, vomiting, muscle or body aches, headaches, fatigue, trouble breathing and fever, the health department said.

There have been at least 55 confirmed human infections of H5 influenza in the US associated with an ongoing outbreak of the virus; 29 of them have been in California. Most of the cases have been among farm workers.

A Canadian teenager has been hospitalized in critical condition with the virus since earlier this month, according to health officials in Canada. It is still unknown how the teen caught this strain of flu.