Friday, May 22, 2009

This flu's been around for years: Science

A new report in the journal Science suggests the Type A H1N1 swine flu virus that is spreading around the world is a truly cosmopolitan virus, and may have been present in pigs for a long time before shifting to humans.

The report was released this morning by Science, written by a team of more than 60 researchers, led by Rebecca Garten, of the WHO Collaborating Center for Influenza, Centers for Disease Control and Prevention.

Portions of the genetic material “of this lineage of Eurasian swine viruses were originally derived from a wholly avian influenza virus that is thought to have entered the Eurasian swine population in 1979 and continues to circulate throughout the region,” the report said.

But other portions hail from North America, and still others from Asia. And it is related to a lot of previous flus, since flu viruses regularly swap genetic material.

The first human cases were reported in Mexico only a couple of months ago, but perhaps the newest information is that researchers now believe this virus may have evolved into its current form and been spreading among pigs for a long time before jumping to humans. Because these diseases are not closely tracked among swine populations, it might have gone unnoticed.

“This virus might have been circulating undetected among swine herds somewhere in the world,” the authors said.

They don't know where.

“Several scenarios exist, including reassortment in Asia or the Americas, for the events that have lead to the genesis of the novel A(H1N1) virus. Where the reassortment event(s) most likely happened is currently unclear.”

One of the issues for public health officials today is to keep close track of the virus, to see if it changes again—potentially making moot the work to develop a vaccine to the current form.

“ Worldwide monitoring of the antigenic and genetic properties of the novel A(H1N1) viruses continues for, among other reasons, detecting any changes and thus any necessity for selecting further vaccine candidates.”

© Jan TenBruggencate 2009

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