Hong Kong ( CNN ) -- China has one of the oldest food cultures in the world and , like that acme of Western food culture French cuisine , the food needs to be fresh . At Sei Wui , a remote town in western Guangdong Province , a live goose will cost you little more than $ US3 a bird . `` They 're 18 kwai a piece , '' said one market trader , using the Chinese vernacular for the renminbi , China 's currency , and pointing to her gaggle of geese honking furiously at one end of a bamboo pen . `` Buy it now and they 'll cook it for you , '' she added , pointing down the road to a small stall doing a brisk business serving a lunchtime crowd of pavement diners . In southern China , it 's said that people will eat everything with four legs except for the table . Whether it 's a chicken , a goose or even a frog , if its heart is still just beating by the time you get it home , all the better . It may taste delicious ; but the way the birds are handled , stored and slaughtered has the potential to make you very sick . It 's no accident , then , that China 's public health authorities are now proactively targeting small towns and villages , taking throat swabs from live food dealers and their customers in wet markets where the rough and ready food culture provides a perfect environment for viruses -- such as H7N9 bird flu -- to flourish . As with all things in China , the scale of the undertaking is witheringly massive . China 's Ministry of Agriculture , says its medical dragnet has taken samples from poultry markets , farms and slaughterhouses across the country . So far , 84,444 samples have been taken , 47,801 have been tested and 39 samples confirmed as H7N9 positive . Of these , 38 positive samples came from live poultry markets in the Shanghai municipality and Anhui , Zhejiang and Jiangsu provinces . One sample , worryingly , was found in a feral pigeon ; an indication of the virus 's ability to spread undetected in wild species . `` Basically , at the moment poultry seems to be the source of the virus so there 's a risk if there 's direct contact with the poultry or indirect contact with the fecal matter or other products . Of course , if the food is being cooked properly then the risk is limited , '' said Dr. Leo Poon Lit-man , associate professor , at the School of Public Health at the University of Hong Kong . While the World Health Organisation has not established a direct link , medical investigators are concentrating their efforts on China 's poultry farms and vendors . `` That is the reality , '' he said . `` That is what we learned from H5N1 , '' he added , referring to the outbreak of the bird flu virus in Hong Kong in 1997 that killed six and left 18 seriously ill. Like most of China , Hong Kong back then liked its chickens fresh . Poultry in bamboo cages on street corners was a common sight and grandmothers could be regularly seen blowing on chickens ' anuses -- a common local method of checking the bird 's cloaca to gauge its age . All of these practices have ended in Hong Kong . After 1997 , millions of poultry were slaughtered and hundreds of vendors put out of business . According to Poon , reducing the risk in any market place is not just a matter of improving hygiene , restricting transport and creating overnight `` rest days '' are all ways of bringing down the viral load in China 's ubiquitous wet markets . `` Once a month we leave a day that allows the poultry to sleep and then on that day we have a very thorough cleaning procedure of the market , '' Poon said , adding that the almost 24/7 nature of many market places in China made it difficult for health authorities to break the cycle of the virus . `` Basically , we come up with a package -- we need more than one single measure to reduce the risk , '' he added . Virologists , meanwhile , are now looking at how viruses pass , not just from animals to humans , but from humans to animals and then back to humans again . According to Professor Gabriel Leung , head of the Department of Community Medicine at Hong Kong University , the spread of disease does not just work in one direction . He said that dangerous outbreaks of epidemics such as SARS and bird flu are a wake-up call , demonstrating that the fate of humans is inextricably linked with that of the animals we raise and eat . `` It reminds us that human health and veterinary health are one and the same thing and we need to be constantly vigilant , '' he said . `` We are linked to animals not just by contact but also by the food chain . ''
Chinese society demands that food be as fresh as possible . But problems arise with the way live poultry is prepared , stored and sold . China 's public health authorities taking throat swabs from live food birds . A strain of bird flu virus has resulted in more than 17 deaths .