China has confirmed the first known human case of the H3N8 strain of avian flu.

H3N8 is known to have been circulating since 2002 after it first emerged in North America. It is known to infect horses, dogs, and seals, but has not been previously detected in humans. 

Chinese health authorities said this strain has a low risk of widespread transmission among people.

The National Health Commission said on Tuesday that a four-year-old boy living in central Henan Province tested positive for the strain in question after he was hospitalized earlier this month with symptoms including fever.

The boy's family lived in an area populated by wild ducks and also raised chickens at home. He seems to have been infected by a bird, and the strain that infected him was not found to have the ability "to effectively infect humans."

Nevertheless, authorities told the public to stay away from dead or sick birds and to seek immediate treatment for fever or respiratory symptoms.

Human infections of zoonotic, or animal-borne, influenzas are "primarily acquired through direct contact with infected animals or contaminated environments, but do not result in efficient transmission of these viruses between people", according to the World Health Organization.

Only two strains of bird flu have been responsible for most cases of human illness from avian flu, H5N1 and H7N9.