Authorities in California, US, have taken extensive precautions to prevent the spread of the virus after a child was confirmed to have bird flu. The state has urged residents to avoid contact with sick or dead wild birds and has issued warnings against eating raw milk or raw milk products.

The California Department of Public Health reported a possible case of bird flu in a child with mild respiratory symptoms on Tuesday, Reuters reported. But it said there was no evidence of human-to-human transmission of the virus and the child's family members tested negative.

California officials said they had sent samples from the child to the US Centers for Disease Control and Prevention for confirmation.

A CDC spokesman said the agency was aware of the presumptive positive case of H5 avian influenza, was cooperating with the state's investigation, and would provide further updates as soon as possible. The agency said the risk to the general public remained low.

Although human infections in the United States are rare, bird flu has infected 53 people since April, according to the CDC, most recently a person in Oregon who was linked to a bird flu outbreak at a commercial poultry operation in the state last week.

In Canada, officials reported earlier this month that a teenager in British Columbia was in critical condition after contracting bird flu.

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 anti-viral medication, the state said. The child had no known contact with any infected animals, but public health experts are investigating possible exposure to wild birds.

“It’s natural for people to be concerned, and we want to reinforce to parents, caregivers and families that based on the data and information, we do not believe the child was contagious,” said Dr. Thomas Aragon, director of the California Department of Health, adding, “and no country has documented human-to-human spread of bird flu in more than 15 years.”

Most U.S. bird flu cases, including 26 in California, have occurred in farm workers who worked with poultry or dairy cattle infected with the virus.

Because bird flu viruses can mutate and gain the ability to spread more easily to people, California public health officials said they are carefully monitoring animal and human transmission.