Baby's infection is the city's fifth case of the H9 virus being found in humans The two-month-old girl whose infection with H9N2 bird flu sparked an alert yesterday is also being treated for possible leukaemia after she was found to have an unusually high number of white blood cells. The baby, who was born at Tuen Mun Hospital, lives most of the time with her parents and grandmother in Shenzhen. She was first admitted to Tuen Mun Hospital for flu symptoms on December 22 and discharged the next day. She was readmitted this week after a Shenzhen doctor found she had a poor appetite and a high white blood cell count. She is believed to have contracted bird flu when she was taken near a wet market or live poultry area. Centre for Health Protection controller Thomas Tsang Ho-fai, said yesterday he had notified the Ministry of Health, World Health Organisation and Macau authorities. H9N2 is an avian virus that has been found in ducks and chickens for many years. Infection in humans is rare and usually mild. Dr Tsang said this was the fifth time the virus had been found in humans in Hong Kong. Three girls and a boy were confirmed to have suffered from H9N2 infection in 1999, 2003 and 2007. The case came to light on the day live chicken sales resumed after a 21-day shutdown because of an outbreak of the much more serious H5N1 strain that killed chickens on a Yuen Long farm and sparked a cull. Hong Kong has been on a 'serious response level' - one notch higher than alert - for influenza and bird flu since December 9, when the outbreak on the farm was confirmed. Dr Tsang said yesterday the two strains should not be confused. The centre would not be complacent and would closely monitor the situation. Unlike H5 or H7 bird flu, H9 - despite being viewed by some experts as a more likely candidate to trigger the next flu pandemic - is not a notifiable disease in Hong Kong. Infectious diseases specialist Lo Wing-lok, who wrote a book on bird flu two years ago, said H9N2 had been 'with us even before 1997 when H5N1 jumped to humans'. 'The baby most likely contracted it at wet markets,' Dr Lo, chairman of People's Health Action, said. 'The lesson to be learned for parents is not to take their children to the wet markets, near bird droppings or areas where there are poultry.' He said the city's health authorities had not made H9 bird flu notifiable because it did not cause serious disease. There were no quick tests for it and no vaccine. The anti-viral drug Tamiflu could help sufferers, as the virus had not shown resistance to it in those given the drug. Dr Tsang said further genetic sequencing was being conducted on the H9N2 virus to determine whether it was completely of avian origin. 'As the girl was staying in Shenzhen for the whole incubation period, we have informed the Guangdong health department,' he said.