An H3N8 strain of bird flu has been detected in humans for the first time, in China’s central province of Henan. The four-year-old boy infected had been in contact with chickens and crows raised at his home, according to reports from China’s National Health Commission. Avian influenza or bird flu as it is commonly known is a highly contagious viral disease with the first reports of human cases in the 1990s. Some strains of the bird flu, such as with H3N8 now, have been passed to humans but this is currently very rare, and usually occurs after very close contact with infected birds or animals. H3N8 viruses circulate widely in birds and in horses and have also been detected in dogs in North America. “We often see a virus spread to a human and then not spread any further so a single case is not a cause of great concern,” said Sir Peter Horby, professor of emerging infectious diseases and global health, University of Oxford. “There is no reason to think it will go any further,” said Prof Paul Digard from the Roslin Institute, University of Edinburgh, adding that Chinese authorities had not reported any illness in the immediate contacts of the infected boy. However, Horby and other disease experts said the widespread transmission and record number of outbreaks of avian flu in birds across the UK, US and Europe this year was a cause of concern as it increased the opportunity for avian viruses to mix and mutate and for human infection. “I do generally believe we need to be increasing influence surveillance globally quite concertedly right now. Apart from H3N8, we have seen a number of other new spillover events of influenza from poultry to people over recent years including H5N8 in Russia and H7N9 and H10N3 in China,” said Alexandra Phelan, assistant professor at the centre for global health science and security at Georgetown University. Marius Gilbert, an epidemiologist at the Université Libre de Bruxelles in Belgium, said a novel virus should always be looked at very carefully, “especially when it is a reassortant, as it can have unpredictable capacity in terms of transmission and virulence in human population”. Dr John McCauley, from the World Health Organization collaborating centre for reference and research on influenza, said the case was an “unusual one” and was being investigated by the WHO and its counterparts in the UN Food and Agriculture Organization. In the UK, consumers can no longer buy free-range eggs, with birds not having been allowed outdoors since November due to close to 100 outbreaks of avian flu. However, there have been fewer than five cases of transmission from an infected bird to a human recorded in the UK – most recently in January, when a man caught it from ducks he kept inside his home.