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Mix with human virus is bird flu's danger

The spread of Asian bird flu to a 10th country, China, is worrying but the real threat is that it might jump from one human to another, and then mutate to a deadly hybrid strain, an expert said.
/ Source: Reuters

The spread of Asian bird flu to a 10th country, China, is worrying but the real threat is that it might jump from one human to another, and then mutate to a deadly hybrid strain, an expert said Tuesday.

“Those are the two most important things,” Professor Albert Osterhaus, a leading virologist at Erasmus University in Rotterdam, Netherlands, said in an interview Tuesday.

There is no evidence that the bird flu, which has struck from Pakistan to Japan and killed eight people, has passed directly between humans.

Scientists fear if it does, this could increase its ability to mutate, possibly leading to a new virus that could spread as rapidly as human influenza, yet carry the surface proteins of an avian virus against which people have no immunity or antibodies.

'A virus with a pandemic potential'
“Then you would end up with a virus with a pandemic potential that could spread worldwide,” Osterhaus said.

Although the odds of that are very low, Professor Roy Anderson of Imperial College London, said they rise with each new infected nation.

“The more countries it spreads to and the more chickens it infects, then the net probability of something that unpleasant increases,” he said.

The worst-case scenario is that a person gets both human and avian flu, and that the two strains fuse -- though the virus might also adapt to humans on its own.

Protective measures
The World Health Organization has described the avian virus rampaging through Asia as a serious global threat to human health and has urged governments to provide funds and technical assistance to countries.

Osterhaus says it is time to update global pandemic preparedness plans: “No country in the world is fully prepared for that.”

The influenza pandemic of 1918, the biggest the world has seen, killed 20 million-40 million people worldwide. Scientists have warned about the threat of the next global pandemic for years.

In 1997 six people died in Hong Kong during an outbreak of avian flu and 1.4 million birds were slaughtered.

“This is really a warning for a pandemic outbreak,” Osterhaus said, referring the latest avian flu outbreak.

“The chances of this happening are not very big. But even a small chance of something as horrendous as a pandemic flu outbreak is something we should take seriously.”

Origin unclear
Scientists are still unclear about how bird flu emerged. Osterhaus believes it was transmitted by migratory birds to domestic poultry and then “heated up” or mutated and spread from flock to flock.

Why most of its victims are children is also puzzling but the virus is known to be excreted in the feces of birds which could provide some clues.

With animal illnesses posing such serious threats to humans, Imperial’s Anderson stressed the need for better monitoring of infectious disease outbreaks in animals and a method of tracking the movement of livestock around the world.

The SARS (Severe Acute Respiratory Syndrome) virus, which jumped from animals to humans, killed hundreds and infected thousands.

“We’ve got to invest more in international surveillance and cooperation and to develop research capabilities ... to develop a diagnostic method quickly and to look for antivirals and vaccines quickly,” he added.

Osterhaus echoed the urgency of improving the speed with which vaccines can be developed and produced. In the interim he said stockpiling of antiviral drugs should be considered.