A researcher works on a vaccine for H1N1 flu virus at the Infectious Disease Laboratory at the Centers for Disease Control in Atlanta, Georgia May 6, 2009. -- PHOTO: REUTERS
WASHINGTON - THE most complete analysis yet of the new H1N1 flu virus shows it must have been circulating undetected for years, most likely in pigs, researchers said on Friday.
They said it is important to start doing better surveillance of influenza viruses in pigs, as they are clearly a potential source of human pandemics.
'Pigs have become a reservoir of viruses with the potential to cause significant respiratory outbreaks or even a possible pandemic in humans,' the international team of researchers reported in the journal Science.
'This virus might have been circulating undetected among swine herds somewhere in the world,' they added.
They also confirmed the odd mixture of human, pig and bird genes in the new virus, which has infected more than 11,000 people in 42 countries, and killed 86 of them.
A team at Britain's Cambridge University, the US Centres for Disease Control and Prevention and elsewhere sequenced the genetic codes of 51 different samples of the new virus from the United States and Mexico.
They confirmed what flu experts have been saying for years - that influenza viruses can not only mutate quickly into new forms, but can swap whole segments of genetic information with other viruses, creating new versions to infect people.
How this particular mixture arose is still a mystery, they said.
'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,' they wrote.
They also said they cannot yet find out how this particular virus acquired the ability to infect people. It does not have the usual mutations that allow animal viruses to jump into people and then to pass easily from one person to another. -- REUTERS
