A 49-year-old man in Sichuan has died of H5N6 bird flu in the first known human infection of the strain in the world.
The man from Nanchong , Nanbu county, had been in contact with dead poultry that had the disease, said China News Service. He died after being diagnosed with acute pneumonia.
Citing an online county government statement, Sichuan's provincial news portal reported that the man had became seriously ill by April 22, but it was not clear when he first showed symptoms or died.
A sample from chickens raised by a farmer in Nanbu tested positive for bird flu on April 23. The strain was confirmed to be H5N6 by the National Avian Influenza Reference Laboratory on Saturday.
Experts consider it an isolated case and the risk of human-to-human transmission very low as no one who had been in close contact with the man had shown symptoms. Some 1,338 poultry were culled and fowl in nearby areas were being monitored, but no abnormalities were found.
Chen Ze , a professor at the Shanghai Institute of Biological Products, said it was very likely an isolated case. "The public do not need to worry too much. The government should step up monitoring," said Chen.
But Yuen Kwok-yung, a professor of microbiology at the University of Hong Kong, said: "Nobody knows how pathogenic or transmissible it is in humans as it is a different ball game."
Though all mainland chickens should be immunised with the H5N1 vaccine, the H5 of this H5N6 may be very different from the H5 of the H5N1 vaccine, so outbreaks could still happen, Yuen said. It was also possible the vaccine had been poorly administered or not given at all.
Last year three types of bird flu - H7N9, H10N8 and H6N1 - infected humans for the first time, all in China. About one-fifth of the 419 cases of H7N9 infections proved fatal. Two people contracted H10N8, while a woman in Taiwan who was infected with H6N1 bird flu recovered.
"We don't know whether this indicates an increase in virus activity or the mainland authorities have done more tests and become more transparent," said Dr Ho Pak-leung, another microbiologist from at HKU.
The genome of the virus that infected the patient with H5N6 is expected to be announced next week and will show whether there was any mutation, Ho said.
Hong Kong's Centre for Health Protection said it was monitoring the H5N6 case.