Pet birds may harbour killer flu

Ring-nosed parakeets harbour potentially deadly disease

A virus found in pet birds could trigger a deadly mass outbreak of flu, scientists have warned.

A team from the National Institute of Animal Health in Tsukuba, Japan, found that Indian ring-necked parakeets pose a possible danger.

The researchers discovered that the birds harbour avian flu viruses closely related to the strain that killed six people in Hong Kong in 1997.

New Scientist magazine reports that the scientists examined birds that died after being imported to Japan from Pakistan.

The viruses that they discovered are also able to infect chickens and mice.

They were of the H9N2 variety, a type of bird flu that infected two people in Hong Kong in 1999 and five people in China last year.

H9N2 causes only mild symptoms in people and is not a threat in its existing form.

However, it is very closely related to a much more lethal strain, H5N1.

Jumped to humans

This strain normally infects chickens. But in Hong Kong in the summer of 1997, it jumped directly to humans.

A total of 18 people were infected, and six were killed, including a three-year-old boy.

The outbreak prompted the mass slaughter of millions of chickens in Hong Kong's open-air markets to contain the virus.

Dr Terrence Tumpey, of the US Department of Agriculture in Athens, Georgia, told New Scientist that the H9N2 virus could cause a serious outbreak in humans if it mutates or mixes with more virulent influenza A strains such as H5N1.

Masaji Mase, who led the Japanese research, says countries that trade in pet birds should adopt quarantine and surveillance procedures.

He said: "I think that quarantine is most important."

There have been three great flu pandemics in recent history.

In 1918, Spanish flu swept the globe, killing 40 million people before disappearing as mysteriously as it arrived.

Its origins remain unclear. Avian flu strains caused two smaller pandemics in 1957 and 1968, which each killed over a million people.