A child who is believed to be infected with H5N1 may have caught the virus from drinking raw milk, health officials said on Tuesday.

The child from Marion County, California, began vomiting and developed a high temperature after drinking a glass of unpasteurised milk, local health officer Dr Lisa Santora told reporters.

After being taken to A&E, the child tested positive for influenza.

Though the exact strain is yet to be determined, officials suspect it is H5N1 - the bird flu that has infected almost one thousand herds of dairy cattle in the US this year, the bulk of which are in California.

Other household members who drank the same milk didn't develop symptoms, but had consumed the milk in much smaller quantities by adding it to their coffees, Dr Santora said.

If H5N1 is confirmed, it will be the first time a person has contracted the virus directly from drinking raw milk. Most of the 60-odd cases detected in the US this year have been from direct contact with sick cattle or poultry.

However, in May, 24 farm cats contracted the virus from drinking raw milk from infected cattle. Half of the cats died, and all had severe symptoms including "stiff body movement, ataxia, blindness, circling, and copious oculonasal discharge," the US Centres for Disease Control said.

The news comes after traces of live H5N1 virus were detected in batches of unpasteurised milk sold at retail stores across California last week. The milk was produced by Fresno-based brand Raw Farm, the largest producer of raw milk in the state.

While pasteurised milk undergoes a rigorous heating process that kills bacteria and viruses such as H5N1, the raw variety can lead to a number of serious health risks, including infections like salmonella, E. coli, brucella, campylobacter and listeria.

For this reason, US health agencies have long since warned of the dangers of consuming raw milk. But several public figures - including incoming US Health Secretary Robert F. Kennedy Jr and celebrity Gwenthyn Paltrow - continue to promote its consumption.

Raw milk sales have grown by 20 per cent over the last year despite the risk of H5N1 growing over the same period.