Friday, May 01, 2009

Swine Flu Ancestor Born on U.S. Factory Farms

Wired Science: "Scientists have traced the genetic lineage of the new H1N1 swine flu to a strain that emerged in 1998 in U.S. factory farms, where it spread and mutated at an alarming rate. Experts warned then that a pocket of the virus would someday evolve to infect humans, perhaps setting off a global pandemic.
The new findings challenge recent protests by pork industry leaders and U.S., Mexican and United Nations agriculture officials that industrial farms shouldn’t be implicated in the new swine flu, which has killed 176 people and on Thursday was formally declared a pandemic by the World Health Organization.
“Industrial farms are super-incubators for viruses,” said Bob Martin, former executive director of the Pew Commission on Industrial Animal Farm Production, and a long-time critic of the so-called “contained animal feeding operations.”
As Wired.com reported on Tuesday, geneticists studying the composition of viruses taken from swine flu victims described it as the product of a DNA swap between North American and Eurasian swine flu strains.
On Wednesday, Columbia University biomedical informaticist Raul Rabadan added new information on the virus’ family history in a posting to ProMed, a public health mailing list. His description paralleled that of other researchers who had analyzed the new strains, but with an extra bit of detail. Six of the genes in swine flu looked to be descended from “H1N2 and H3N2 swine viruses isolated since 1998.”
Experts contacted by Wired.com agreed with Rabadan’s analysis. For researchers who track the evolution of influenza viruses, the news was chilling.
H3N2 — the letters denote specific gene variants that code for replication-enhancing enzymes — is the name of a hybrid first identified in North Carolina in 1998, the tail end of a decade which saw the state’s hog production rise from two million to 10 million, even as the number of farms dropped. H3N2 originated in a relatively benign swine flu strain first identified in 1918, but had absorbed new genes from bird and human flus."

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