New bird flu virus could spark pandemic
By Karen Herzog
July 13, 2013
A new bird flu virus responsible for at least 37 deaths in China since March – more than one-fourth of those it infected – has the potential to spark a global outbreak, a team of researchers led by virologist Yoshihiro Kawaoka of the University of Wisconsin-Madison and the University of Tokyo concludes in latest findings.
Once live poultry markets in China reopen this winter, after being shut down in recent months to stop the spread of the H7N9 virus, scientists expect there will be more illnesses and more deaths, Kawaoka, one of the world’s leading experts on avian flu, said in a telephone interview.
Scientists don’t know whether the virus will have the ability to spread beyond China. They also don’t know whether H7N9 will re-emerge in strains already seen, or whether new strains will appear. Viruses circulate and naturally mutate in nature.
“It almost certainly will come back in the winter,” Kawaoka said, “and very similar viruses to this one are also there in China. This is not the only virus that will transmit to humans.”
Scientists elsewhere are working on developing a vaccine to provide some protection against H7N9.
Most human cases have been linked to contact with chickens, though the World Health Organisation and others have warned that the virus could be spread among humans, possibly triggering a global pandemic.
The new research published in the journal Nature is a comprehensive analysis of two of the first human isolates of the H7N9 virus from patients in China.
Kawaoka noted that the H7N9 virus is “quite different” from the 2009 H1N1 “swine flu” virus that most severely affected those ages 25 and younger worldwide. H7N9 in China has disproportionately hit those over age 60, and males in particular, Kawaoka said.
Scientists in Madison and Tokyo researched the H7N9 virus’ pandemic potential by studying how it infects various mammals, how it replicates in cells, and whether it could be spread by respiratory droplets through coughing and sneezing.
Scientists laid the groundwork for the research and analysed the results in Madison. In Tokyo, they transmitted the virus to mice, ferrets, macaque monkeys, miniature pigs, chickens and quail to see how each responded, and whether the animals became infected.