Hong Kong Raises Bird Flu Alert After H5 Cases

Although H5N1 is mainly a disease among birds, it may mutate into a form that spreads easily among people.

Hong Kong health authorities raised the city's bird flu alert level to "serious" on Tuesday after the H5 virus killed dozens of chickens at a farm, prompting the cull of 80,000 birds.

Laboratories in the city were now trying to determine the precise identity of the virus. A leading expert said it was likely to turn out to be the highly pathogenic H5N1 strain, which turns up regularly in flocks in Asia, parts of Europe and Africa.

"It's highly likely it's the highly-pathogenic H5N1 strain because others (other H5 strains) don't kill chickens like this. But this has to be confirmed," virologist Malik Peiris at the University of Hong Kong said.

Although H5N1 is mainly a disease among birds, it may mutate into a form that spreads easily among people.

If that happens, it could trigger a pandemic and kill millions. Even in its current hard-to-catch form, H5N1 has infected 387 people since 2003, killing 245 of them.

The city's Health Secretary York Chow said the affected farm was in Hong Kong's northern Yuen Long district near the border with China, which reported the unusual deaths of 60 chickens on Monday.

"After a series of tests, we have confirmed this morning that the chickens died from the H5 virus," Chow told reporters, adding three dead chickens were tested and 20 faeces samples were taken.

CULLING

Workers clad in masks, white medical suits and black rubber gloves began the mass cull of some 80,000 birds at the farm on Tuesday afternoon, and were shown stuffing piles of chicken carcasses into black bin bags.

All chickens within a 3 km radius of the farm will be destroyed, along with birds at a wholesale market, Chow said.

Chicken farms in Hong Kong observe strict biosecurity measures to prevent disease and cross-infection between species, and chickens are vaccinated against the H5N1.

It was not immediately known how the chickens became infected. "It could be injection (of the virus) from wild birds. These (incidences) increase in winter. But it is not the only possibility," Peiris said.

The scenes were reminiscent of previous culls in 1997 and 2001, when the H5N1 virus prompted the slaughter of more than one million birds each time. In the 1997 outbreak, six people died.

Chow also ordered a precautionary three-week ban on poultry imports to contain any potential spread of the virus.

"We will ban all the outlets of all chickens from our farms for 21 days and also suspend all the imports of chicken and poultry including birds for the next 21 days," Chow added.

The last bird flu outbreak at a Hong Kong farm occurred in early 2003.