Bird Flu Returns, and This Time It's Mutated

During the last couple of flu seasons, we were all worried about H1N1, a new and virulent strain of influenza, but this winter we may have to contend with a much deadlier foe: H5N1, or bird flu. Some Asian countries are reporting this week the first cases of a mutant strain of the virus spreading in poultry.

The U.N. Food and Agriculture Organization (FAO) reported on Monday that the H5N1 virus has mutated, something that public health officials had feared would happen and that could possibly make the virus more dangerous to people.

In its original form, H5N1 primarily infects wild birds and poultry, including geese, chickens, ducks and turkeys, but only rarely jumps into people. Still, the fact that some people have become infected with H5N1 by eating improperly prepared and contaminated poultry — the virus has killed 331 people and infected 565 since it first appeared in 2003 — led experts to warn that it was only a matter of time before it altered into a form that made it easier to spread to humans.

It's not clear yet whether that has happened, but health authorities are concerned by the an new H5N1 variant spreading in poultry in both China and Vietnam; the new strain is resistant to current vaccines. In the years since H5N1 began spreading among bird and poultry flocks, millions of birds have been culled, and many countries have adopted vaccination programs to inoculate domestic fowl to prevent the spread of the virus. But six countries have continued to see H5N1 among their poultry population each year: Bangladesh, China, Egypt, India, Indonesia and Vietnam.

And after declining since a peak in cases in 2005-06, when some 4,000 cases were reported, the rate of H5N1 outbreaks among both animals and people has started to inch up this year. "When you look at 2011, there is a trend upward in cases," says Juan Lubroth, FAO's chief veterinary officer. "And in several countries that had experience with H5N1 already, they are seeing a new introduction of [the virus]. We want to alert the community that we are seeing an upswing of cases."

Already, Cambodia, which shares a border with Vietnam, has reported eight cases of H5N1 infection this year, and all have been fatal. It's not clear whether any of these involved the mutant strain, but experts say the more cases of infection among humans and birds there are, the more opportunities the virus has to recombine and mutate into a form that is more easily transmissible to people.

Containing the new H5N1 strain, known as H5N1 2.3.2.1, may be a challenge, since many of the infected fowl are wild species that migrate, and can easily spread the virus over thousands of miles. In the past two years, experts have tracked the original version of H5N1 to regions where it has never been reported before. It has also shown up again in places that had been virus-free for several years, including Israel, the Palestinian territories, Bulgaria, Romania, Nepal and Mongolia.

The same could happen with H5N1 2.3.2.1. "What has surprised us a bit is the geographical spread and also some concerns that the vaccine readily used in combating H5N1 is not as effective with this particular strain," says Lubroth. "There is a concern there, so we wanted to alert the world community."

http://healthland.time.com/2011/08/30/its-back-bird-flu-returns-and-this-time-its-mutated/