A cull of tens of thousands of chickens was continuing in Hong Kong Thursday as officials tried to calm fears over a new outbreak of bird flu, reported dpa.
More than 75,000 chickens had been slaughtered by Thursday afternoon at the farm in the Yuen Long district where the outbreak was detected and at a nearby wholesale market in Cheung Sha Wan.
Meanwhile birds killed by the virus were tested to find out if the type of bird flu they contracted was the H5N1 strain that jumps more easily from chickens to humans.
The the latest avian influenza scare gained pace on Tuesday when it was announced on that 200 chickens had died of the H5 virus at one farm. Hong Kong saw the first human deaths from bird flu in modern times in 1997.
Hong Kong Health Secretary York Chow said scientists were continuing to look into why the H5 virus had apparently been able to infect birds vaccinated against bird flu.
However, the city's Director of Health, Lam Ping-yan, said there was no evidence yet that the Dutch-made vaccine currently used on chickens in Hong Kong was no longer effective.
He said the government would consider at a later stage whether to use an alternative vaccine widely used in mainland China which was more effective against the H5N1 strain.
Six people died and 12 others were infected in an outbreak of bird flu in Hong Kong in 1997 that led to the culling of 1.2 million birds. Millions more birds were slaughtered in outbreaks in 2001 and 2002.
Hong Kong later implemented strict controls on markets and chicken imports and escaped any human infections when bird flu swept the region in 2006.
However, the new outbreak raises the possibility that the virus has mutated to develop immunity to the vaccine currently being used on chickens.
Experts have repeatedly warned that the H5N1 strain of bird flu threatens a global pandemic if it mutates into a form that is more easily transmitted between humans.