Tuesday, March 14, 2006

H2H Avian Flu…Who Knew?

H2H Avian Flu…Who Knew?

‘H2H’ may soon join our lexicon much in the way ‘Y2K’ did at the turn of our last global crisis. If H2H is new to you, it is shorthand for ‘Human to Human’, as in Human to Human transmission of the bird flu. The term H2H is spreading just like the bird flu. In February, the term was searched on Yahoo 471 times; bloggers enter H2H into Technorati’s search engine about eight times a day.

H2H is important because it represents the next big step in the evolution of the H5N1 virus. The question is, when will H5N1 go H2H? The answer is, it already has! With all the hype surrounding bird flu, why don’t more people know about this development? Why aren’t the CDC and WHO telling us?

It turns out that they are, in a muted way. Here’s the alert level posted on WHO’s site:

Note we are in phase 3, “No, or LIMITED H2H transmission”.

From the CDC:

“While H5N1 does not usually infect people, human cases of H5N1 infection associated with these outbreaks have been reported Most of these cases have occurred from direct or close contact with infected poultry or contaminated surfaces; however, a few rare cases of human-to-human spread of H5N1 virus have occurred, though transmission has not continued beyond one person.”

In reality, the medical world has known about H5N1 H2H for awhile. One of medicine’s most prestigious periodicals, The New England Journal of Medicine, featured this study in January of 2005:

Results: The index patient became ill three to four days after her last exposure to dying household chickens. Her mother came from a distant city to care for her in the hospital, had no recognized exposure to poultry, and died from pneumonia after providing 16 to 18 hours of unprotected nursing care. The aunt also provided unprotected nursing care; No additional chains of transmission were identified....
Conclusions: Disease in the mother and aunt probably resulted from person-to-person transmission of this lethal avian influenzavirus during unprotected exposure to the critically ill index patient."

Why aren’t we panicking? The rare cases of documented H2H for H5N1 prove that the chain of transmission is very short. It appears that the virus does not efficiently transfer between humans, leading to the rare H2H infections. As the virus changes, it could acquire the ability to spread easily between humans—or it may not. The only safe prediction is that this virus will change and that the best thing for us to do is to support the researchers who are tracking H5N1.

While there is no cause for panic, there is one fact surrounding H5N1 that is of concern. The most recent great pandemic in 1918 killed upwards of 50 million people worldwide, according to the CDC. Its mortality rate (number of deaths as a percentage of total people who got infected) was under 2.5%.
Today’s H5N1has infected a total of 177 people, killing 98. Its mortality rate is 55%.
Let’s hope that like Y2K, H2H will become a footnote in history, rather than a chapter of global suffering.

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