WIKIMEDIA, GAVIN SCHAEFERThe Avian influenza A (H7N9) virus, a new strain of bird flu that emerged in China earlier this year, has likely been passed directly between a father and his daughter in the eastern part of the country, according to research published this week in the British Medical Journal (BMJ). It is the first reported case of human-to-human transmission, but researchers have stressed that it does not mean the virus has developed the ability to spread easily between people, reported BBC News.

By the end of June, Chinese authorities had recorded 133 cases of H7N9, including 43 deaths. Most of the people infected had visited markets selling live birds or come into contact with live poultry in the week or so before they fell ill. On this occasion, however, a 32-year-old woman who had not knowingly been exposed to live birds got the virus after...

Scientists from the Jiangsu Provincial Center for Disease Control and Prevention found that the genomes of the viruses taken from both patients were nearly identical, suggesting that the flu had spread from father to daughter. But none of  the patients’ 43 close contacts who were tested became infected, indicating that the ability of the virus to jump between humans is limited.

James Rudge of the London School of Hygiene and Tropical Medicine, who co-wrote an accompanying commentary in the BMJ, told the BBC that limited transmission between humans has been seen before in other bird flu viruses, such as H5N1, and is therefore not surprising.

“It would be a worry if we start to see longer chains of transmission between people, when one person infects someone else, who in turn infects more people, and so on,” said Rudge. “And particularly if each infected case goes on to infect, on average, more than one other person, this would be a strong warning sign that we might be in the early stages of an epidemic.”

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