Hong Kong may see its first H7N9 human infection within months now that a suspected case has emerged across the border in Guangdong province, the Centre for Health Protection says. A 51-year-old woman is believed to have been infected with the deadly strain of bird flu, according to a preliminary test in Huizhou . Doctors have sent a biological sample to the Chinese Centre for Disease Control and Prevention in Beijing for confirmation. Mainland media reported that the woman was a poultry butcher in Boluo county, Huizhou. According to the Centre for Food Safety, Huizhou has eight farms that supply live poultry to Hong Kong. Centre for Health Protection controller Dr Leung Ting-hung said mainland officials had notified their counterparts in Hong Kong about the suspected case, which, if confirmed, would be geographically the nearest case of human infection to the city. "We should be mindful of the situation, as Guangdong is adjacent to Hong Kong," Leung said. "We are also paying attention to whether the virus has been changing or has the ability to spread from human to human." He said Hong Kong might see its first infection in the next few months if the Guangdong case was confirmed. "After all, cross-border activities are so frequent; we should be prepared for that." We should be mindful of the situation, as Guangdong is adjacent to Hong Kong. We are also paying attention to whether the virus has been changing or has the ability to spread from human to human Centre for Health Protection controller Dr Leung Ting-hung The source of infection was still under inspection by mainland authorities, Leung said, adding that he was unable to provide more background. He said a team of Hong Kong experts would be despatched to Guangdong to assess the situation if the infection was confirmed. He did not say whether the supply of live poultry from the mainland would be suspended to prevent the spread of the disease. To date, there have been 133 cases of H7N9 infection in humans on the mainland since the virus was first discovered in February. Previous studies have found that the virus - which kills around one in three of those who contract it - most often infects the elderly. This month, a 32-year-old woman was reported to have contracted H7N9 by human-to-human transmission in Jiangsu . Leung said avian influenza was usually most active in winter. "But it's only an observation," he said. "There have been H5N1 infection cases in summer, too."