Expert: H5N1 Worst Flu Virus He's Ever Seen

A leading expert said Thursday the H5N1 virus is the worst flu virus he's ever encountered, and far too many gaps in planning and knowledge persist for the world to handle it in the event of a pandemic.

The virus is a vicious killer in poultry, moving into the brain and destroying the respiratory tract, said Robert G. Webster, a virologist at the St. Jude Children's Research Hospital in Memphis, Tenn.

"I've worked with flu all my life, and this is the worst influenza virus that I have ever seen," said Webster, who has studied avian flu for decades. "If that happens in humans, God help us."

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So far, most human cases have been linked to contact with infected birds, but experts fear the virus will mutate into a form that easily spreads from person to person, potentially sparking a global pandemic.

Webster predicted it would take at least 10 more mutations before the H5N1 virus could potentially begin spreading from human to human, but said there's no way to know when — or if — that will ever happen.

"All of those mutations are out there, but ... the virus hasn't succeeded in bringing it together," he said at the end of a two-day bird flu conference in Singapore organized by The Lancet medical journal.

Webster also called for more vaccine to be stockpiled, calling current efforts "miserable."

He said research in ferrets suggests that vaccination with a bird flu virus that circulated earlier in Hong Kong protected the animals from dying when they were later infected with the H5N1 virus now spreading in Vietnam. Such vaccination could potentially be used as a primer to prepare humans for a pandemic flu strain, he said.

Webster said much more research is needed to understand the virus' behavior and how it is spread. Research is being hindered, he said, by cultural issues preventing autopsies of victims. In many Asian countries, where most of the human deaths have occurred, many people do not believe in disturbing the body after death.

He said autopsies have been done on only six of the 113 people killed by bird flu since the virus began ravaging Asian poultry stocks in late 2003.

"The cultural ban in this region on autopsies has to be worked out somehow," Webster said. "Tissues have to be taken from cadavers to understand the biology of these viruses."

Dr. Frederick G. Hayden, a University of Virginia virus expert, said more research also is needed for antiviral drugs.

Hayden is collaborating on the first controlled clinical study looking at the effectiveness of Tamiflu in people infected with the H5N1 virus. It will examine how adults and children in Vietnam, Thailand and Indonesia respond to standard doses of Tamiflu currently recommended for annual seasonal flu versus higher doses.

Health experts have touted the antiviral Tamiflu as the most effective medicine available to fight bird flu, and countries worldwide have been racing to stockpile it in case the virus mutates into a pandemic strain. But little is known about drug resistance and how much Tamiflu should be given to a person infected with the H5N1 bird flu virus. Dosage recommendations are currently not even available for children under 1 year of age.

Hayden said the World Health Organization is expected to announce revised dosing recommendations for Tamiflu soon.