Mexico City ends swine flu alert, no cases in week
MEXICO CITY (AP) - Mexico City lowered its swine flu alert level from yellow to green on Thursday, and the mayor said "we can relax" now that there have been no new infections for a week.
Meanwhile, the A.P has a story out that incorrectly states the origin of the H1N1 virus.
Other scientists believe the new strain could have been circulating in humans long before it reached La Gloria. The new strain's ancestry has ties to a pig farm in North Carolina where in 1998, scientists discovered that pig, bird and human viruses had combined in pigs to form a new strain of swine flu that also infected a handful of humans.
The H1N1 strain goes back further.
Why were the viral genomes of the 1977 H1N1 isolate and the 1950 virus so similar? If the H1N1 viruses had been replicating in an animal host for 27 years, far more genetic differences would have been identified. The authors suggested several possibilities, but only one is compelling:
…it is possible that the 1950 H1N1 influenza virus was truly frozen in nature or elsewhere and that such a strain was only recently introduced into man.
The suggestion is clear: the virus was frozen in a laboratory freezer since 1950, and was released, either by intent or accident, in 1977. This possibility has been denied by Chinese and Russian scientists, but remains to this day the only scientifically plausible explanation.