Re: Bird flu strain infecting fewer wild birds - OIE
Bird Flu Virus May Be Near End of Cycle, Group Says (Update3)
By Jason Gale
May 21 (Bloomberg) -- The bird flu that threatens to spark the first pandemic in almost four decades may be nearing the end of a natural cycle after it killed fewer wild and migratory birds this year, an international veterinary body said.
Kuwait, Bangladesh and Ghana reported initial outbreaks of the H5N1 strain of avian influenza in domestic fowl between late February and early April, according to the World Organization for Animal Health. In comparison, 38 nations recorded initial infections in the first seven months of 2006, mostly in wild birds. The drop in new reports of outbreaks in wild birds ``could indicate the disease is coming closer to the end of a cycle,'' the Paris-based group said today.
Signs the H5N1 threat may be receding would indicate the $2.5 billion pledged by nations including the U.S. and Japan to fund efforts to monitor, manage and eradicate H5N1 and to prepare for a pandemic have been successful. A flu outbreak killing 70 million people worldwide may cause global economic losses of as much as $2 trillion, the World Bank said in June.
``
If we were to say we've won, the war is over, we'd be in a worse mess,'' said Juan Lubroth, head of infectious diseases in the animal health service of the Food and Agriculture Organization. ``This problem is not going to disappear in one or two years.''
The spread of H5N1 to 59 countries during the past four years brought the world closer to another pandemic than at any time since 1968, when the last of the previous century's three major outbreaks occurred, world health experts say.
Increased Risk
Diseased birds increase the risk of human infection and provide chances for H5N1 to mutate into a form that's as contagious to people as seasonal flu. The end of one cycle of infection in birds may mean that another is on its way, said Michael Osterholm, director of the Center for Infectious Disease andPolicy at the University of Minnesota in Minneapolis.
``The lifespan of birds is several years,'' he said in a telephone interview. ``In that time period they cycle through and you have a whole new population that's susceptible to the virus. You expect to see ebbs and flows in prevalence.''
Even if H5N1 were to fade, other families of flu might also produce a virus capable of setting off a pandemic, he said. Other flu researchers have said that the H9N2 strain of flu that infected a girl in Hong Kong might have pandemic potential.
`
Like Earthquakes'
``Pandemics are like earthquakes and hurricanes,'' Osterholm said. ``We're going to have another pandemic, we just don't know when it's going to occur, where it's going to start of what the infectious agent will be.''
H5N1 infected 306 people in a dozen countries since late 2003, according to the World Health Organization. About 60 percent of cases were fatal.
The virus may take as many as 10 years to eradicate from Indonesia, and possibly Bangladesh and Egypt, Lubroth said.
``I think we will see this disease diminish, not disappear, but definitely diminish'' as countries improve their surveillance, detection and response to it, he said in a telephone interview from Rome.
In January and February, Vietnam, Japan, Thailand, Hong Kong, Hungary, the U.K., Pakistan, Turkey, Russia, Laos, Nigeria, Afghanistan and Myanmar reported fresh outbreaks. Almost all of them have been controlled.
Quicker Reporting
Countries such as Ghana, Vietnam and Myanmar are reporting the disease soon after finding it, Lubroth said. ``I would say, three years ago they would not have been able to have done so.''
Most countries overcome avian influenza outbreaks when they occur in animals, the World Organization for Animal Health said. ``The veterinary services in the majority of these countries have successfully dealt with these outbreaks,'' it said.
Still, poultry flocks continue to be infected in countries including Indonesia, Nigeria and Egypt, which ``shows the international community needs to keep up its high level of prevention and control measures of the disease in animals,'' Bernard Vallat, the agency's director general, said in the statement.
The fact fewer countries reported H5N1 in wild birds this year may be attributed to a combination of reasons, including a possible drop in virus levels in the environment, a warmer winter in parts of Europe and the faster response of veterinary authorities, Lubroth said. There is no certainty the same pattern will be repeated next year, he said.
``
The more we study H5N1, the more questions we have,'' Lubroth said. ``Why is this year different from last year, that still has to be teased out.''
Also veterinarians have yet to find those species that are carrying H5N1 and can't be sure whether wild birds are picking up the virus from poultry farms and ``therefore they are more the victims than culprits,'' he said. ``We really have not found the `smoking gun' in wild life. We've not found the wild bird that is happily flying around and shedding H5N1.''
To contact the reporter for this story: Jason Gale in Singapore at
j.gale@bloomberg.net
Last Updated: May 21, 2007 15:44 EDT
http://www.bloomberg.com/apps/news?pid=20601202&sid=af5SEQC7m8hw&refer=healthcare
