BEIJING A Chinese man who died of bird flu last month likely passed the disease on to his father, but there is no evidence the virus mutated into a form which can be easily passed between humans, an official said on Thursday.
The man in the eastern province of Jiangsu was diagnosed with the H5N1 strain of bird flu days after his 24-year-old son died from the disease.
This rare case of two family members struck by the disease drew concern from health authorities, because humans almost always contract H5N1 from infected birds.
Experts fear the virus could mutate into a strain that jumps easily from person to person, risking wider outbreaks.
Chinese Health Ministry spokesman Mao Qun'an said it was likely the man had caught bird flu from his son.
"The initial judgment is that it was an infection from close contact," Mao told a news conference, carried live on government Web site www.china.com.cn.
"It has no biological features for human-to-human transmission," said Mao, adding the father had now recovered.
Mao had already said in December that samples had indicated no mutation of the virus.
But the ministry still did not know the cause of the initial infection, as neither had had any contact with sick or dead birds, he said.
The virus does have a limited capacity for human-to-human transmission, and other cases have been reported in Asia.
With the world's biggest poultry population and millions of backyard birds, China is at the centre of the fight against bird flu. There have been other cases of human infection without confirmed outbreaks among birds in the same area.
The latest cases brought the number of confirmed human infections of bird flu in China to 27, with 17 deaths.
(Reporting by Ben Blanchard; Editing by Nick Macfie)