China’s top health authority is not ruling out the possibility of human-to-human transmission of the new H7N9 bird flu virus strain.
Although the virus does not easily infect humans, the chance of human-to-human transmission is “theoretically possible” , although “highly sporadic”, explained Feng Zijian, director of the Chinese Centre for Disease Control and Prevention’s (CDC) health emergency centre.
“Long-term and unprotected exposure to the infected person might result in another human infection,” he said. Feng added that the small amount of family clusters did not necessarily mean the virus had mutated into a human influenza virus capable of spreading person to person
The elder son of an 87-year-old man who died of the virus on March 4, one of China’s earliest cases, has recovered from the virus, the National Health and Family Planning Commission said.
The dead man’s younger son also died on the same day as his father. Details of his death however, were not available. The CDC said they were currently investigating whether the family cluster involved human-to-human transmission.
At least two family cluster cases have been found in Shanghai, which involved a father and son, and a husband and wife.
As of Thursday, 11 new H7N9 infections have been reported, bringing the total number of confirmed cases to 82.
The first person infected in Beijing, a seven-year-old girl, left hospital on Wednesday and appeared before media in an apparent bid by health authorities to cool concerns about the deadly virus. Her parents were poultry traders.
A four-year-old boy in the capital also infected with the strain but not displaying symptoms remained in quarantine. He was identified as a carrier via a random blood test of people in or near the poultry industry.
Meanwhile, Dr Zeng Guang , CDC chief of epidemiology, said 40 per cent of the people who have tested positive for H7N9 had no recent contact with poultry, raising questions of how they contracted the virus.
"How were they infected? It is still a mystery," he was quoted by The Beijing News on Wednesday as saying.
View H7N9 map  in a larger map
Click on each balloon for more information on individual patients infected: blue, patients infected with the H7N9 virus under treatment; red, those infected with H7N9 who have died; yellow, those who have fully recovered; and pink, those infected other types of the Influenza A virus, including H1N1.