The latest bird flu virus that killed a 39-year-old bus driver in the southern Chinese city of Shenzhen over the weekend is not yet transmissible between humans, Chinese health authorities said.
"The virus found in the patient was 90 per cent similar to H5N1 viruses previously isolated in ducks in China, which suggested that the man was very likely to have been infected through direct contact with a bird," the Shenzhen Center for Disease Prevention and Control said in a statement.
"It is still not transmissible between people," it said, adding that the bus driver was probably infected through direct contact with birds.
Hong Kong's Centre for Health Protection said on Monday that the virus strain found in the man was very similar to that recently found in wild birds in Hong Kong.
An analysis of its genes also found that the virus can be treated by amantadine, a common antiviral drug.
The man, who lived in Shenzhen just across the border from Hong Kong, died from multi-organ failure on Saturday, a week after being admitted to hospital with a fever brought on by the virus, state media reported.
The virus is normally found in birds but can occasionally jump to people. Researchers worry that the virus could mutate into a form that would spread easily between humans.
Hong Kong culled 17,000 chickens at a wholesale poultry market two weeks ago after a dead chicken there tested positive for H5N1 avian virus, and suspended imports of live chickens from the mainland for 21 days in a bid to prevent any spread of the disease.