AN OUTBREAK of 鈥渂ird flu鈥� in a Hong Kong family who visited Fujian province in southern China is fuelling fears that the country will be the source of the next global flu pandemic.
鈥淐hina is a huge country and surveillance [for the virus] is poor,鈥� says Graeme Laver, who helped develop the anti-flu drug Relenza at the Australian National University in Canberra. Flu experts are fearful because Chinese practices of keeping large numbers of different birds in close proximity to humans favours the emergence of new strains of flu.
The family, who had visited Fujian for the Chinese New Year, was struck by tragedy when their 8-year-old daughter became ill and died on 4 February. The father and son also fell ill with similar symptoms. The father died shortly after they returned to Hong Kong, and the son was admitted to hospital where health officials diagnosed his illness as the bird flu virus H5N1. Tests found that the father had also been infected with the virus, but as 快猫短视频 went to press, the reason for the daughter鈥檚 death had not been confirmed. The son has now recovered.
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The immediate worry is that the virus will spread from human to human. So concerned is the World Health Organization that it has activated its global flu response plan, which involves discussing how to develop vaccines against that particular strain of virus.
In 1997, eighteen people in Hong Kong became infected with H5N1, and six died. That was the first time the virus is known to have jumped from chickens to humans. But because it could not pass from human to human, the epidemic spluttered out, averting a global disaster akin to the 1918 flu pandemic that killed at least 20 million people worldwide.
The most likely scenario is that each member of the family contracted the virus directly from poultry that they reportedly came into close contact with in China, says microbiologist Malik Peiris, whose lab at the University of Hong Kong is sequencing the virus. Preliminary results suggest the virus that infected the family does not contain any human flu genes, which makes human to human transmission less likely. But the only way we will know for sure, says Peiris, is if someone who has been nowhere near poultry becomes infected after contact with a flu patient.
Why the flu virus sometimes turns lethal is a mystery, but the worst outbreaks have happened when a human flu virus picks up new genes from fowl flu viruses, or jumps directly from chickens to humans.
Since 1997, Hong Kong has run a rigorous bird flu surveillance programme and slaughtered hundreds of thousands of poultry infected with H5N1. It has also instigated laws that prevent different poultry species mixing in the live poultry markets, which would limit the chances of the virus picking up new genes.
But all those efforts could be in vain because of Hong Kong鈥檚 close proximity to mainland China. In the past three years, H5N1 flu viruses in Hong Kong鈥檚 birds have been evolving at a startling rate, picking up genes from at least three different species of waterfowl, not all of which exist in Hong Kong. Last September, H5N1 was detected in wild birds, confirming that the virus is highly unlikely to be restricted to Hong Kong but must also be circulating in mainland China.