Bird Flu Warning - WebMD

[This post is by WebMD, and will be helpful to those of you just becoming familiar with Bird Flu H5N1]

Tuesday, August 30, 2011
by Daniel J. DeNoon

Bird flu is on the rise, warns the UN’s Food and Agriculture Organization (FAO).

“[It] could mean that there will be a flareup of [bird flu] this fall and winter, with people unexpectedly finding the virus in their back yard,” FAO chief veterinary officer Juan Lubroth suggested in a news release.

Bird flu, for those who may have forgotten, is the bug that health authorities have been losing sleep over since it first infected humans in 2003. Officially called avian influenza, it’s caused by a virus known as H5N1. True to its name, bird flu has devastated chicken flocks in the 63 countries to which it spread.

There’s a lot of good news. Bird flu has never yet learned to spread easily from person to person. Nearly all human infections have come from close contact with poultry or consumption of raw (not cooked) chicken products. And thanks to drastic culling of infected chicken flocks, bird flu has been eliminated from most of the countries in which it has appeared.

The bad news is that when humans do get the bug, it causes a deadly illness. Of the 565 people known to have been infected, 331 have died — nearly a 60% mortality rate. And, the FAO says, bird flu “is still firmly entrenched” in Bangladesh, China, Egypt, India, Indonesia, and Vietnam.

What worries the FAO is that after winding down over the past five years, the last year has seen a rising number of poultry outbreaks, including outbreaks in countries that previously eliminated the virus or were never before affected.

“There is a legitimate concern we are seeing an upswing in the last year compared to the last five,” Lubroth said today in a telephone interview. “We are warning the world that this fall we may be seeing an increased geographical distribution.”

Lubroth suspects that wild bird migrations are spreading bird flu far and wide. He notes that the virus has recently popped up in faraway places such as Israel, the Palestinian territories, Bulgaria, Romania, Nepal, and Mongolia.

There’s another piece of potentially bad news. A mutant H5N1 bird flu virus is spreading in Vietnam. The mutant, dubbed H5N1 2.3.2.1, has evolved to escape the poultry vaccine currently used in Vietnam and perhaps elsewhere.

But there’s no sign that this mutant is more or less virulent than previous versions of H5N1, and no sign that it’s more easily transmitted from person to person. In fact, Lubroth suspects that humans already have been infected with the mutant strain, although the mutant’s genetic fingerprints have yet to be detected in an infected person.

How big a deal is this mutant? It’s nothing new for flu bugs to mutate, says virologist Ruben Donis, PhD, chief of the molecular virology and vaccines branch in the CDC’s influenza division.

“We are not extremely alarmed by this news,” Donis today told me. “This group of viruses has been circulating wildly in Vietnam, and so far there have been very few human infections. Vietnam had no human infections in 2011 so far.”

Lubroth agrees. “This [mutation] should not be interpreted as making the world a more dangerous place. Not at all,” he said.