California's public health department reported a possible case of bird flu in a child with mild respiratory symptoms on Tuesday, but said there was no evidence of human-to-human transmission of the virus and that the child's family members tested negative.
California officials said they have sent test specimens from the child to the U.S. Centers for Disease Control and Prevention for confirmation.
A CDC spokesperson said the agency is aware of the presumptive positive case of H5 avian influenza, is collaborating with the state's investigation, and will provide further updates promptly. The agency has said the risk to the general public remains low.
Although human infections in the United States have been rare, bird flu has infected 53 people since April, according to the CDC, most recently a person in Oregon last week tied to a bird flu outbreak in a commercial poultry operation in the state.
In Canada, officials earlier this month reported that a teen infected with bird flu in British Columbia was in critical condition.
The child in California was in daycare with mild symptoms before the illness was reported, the state said.
Local health officials have contacted potentially exposed caregivers and families to check for symptoms and offer preventive treatment and testing if they become symptomatic.
The child and all close family members have been treated with preventive medication, the state said. The child had no known contact with an infected animal, but public health experts are investigating possible exposure to wild birds.
"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," said California health department director Dr. Tomas Aragon, adding, "and no human-to-human spread of bird flu has been documented in any country for more than 15 years."
Most U.S. bird flu cases, including 26 in California, have occurred among farm workers working with poultry or dairy cows that were infected with the virus.
Because bird flu viruses can mutate and gain the ability to spread more easily between people, California public health officials said they are monitoring animal and human infections carefully.
The state urged residents to avoid contact with sick or dead wild birds and renewed the warning against consuming raw milk or raw milk products, which have not undergone pasteurization to inactivate the bird flu virus and other harmful pathogens.