Researchers hope to predict the hot spots where dangerous flu strains may… (U.S. Centers for Disease…)
No one knows where the next deadly pandemic flu is likely to emerge. But a new analysis of flu surveillance and other data from a UCLA-led team suggests that coastal and central China and Egypt's Nile Delta might be areas worth watching.
UCLA postdoctoral researcher Trevon Fuller and colleagues published their work online on March 13 in the U.S. Centers for Disease Control and Prevention journal Emerging Infectious Diseases. The thinking behind their research goes something like this:
Dangerous influenza outbreaks, including pandemics in 1957 and 1968 that killed around a million people apiece, arise when new, aggressive flu strains arise through a process known as reassortment. A single animal is infected with several flu viruses at the same time -- which then swap genetic bits to create new and sometimes deadly strains.
Fuller and his colleagues used new techniques to assess conditions in a number of places to see how likely a reassortment event might be. While a new pandemic could possibly emerge from a number of combinations of flu strains, the team focused on reassortment between human H3N2, a version of which was prevalent in the U.S. this flu season; and avian H5N1, a widespread bird fluthat has been rare in humans so far but has proven deadly among the hundreds of people it has infected.
(Flu watchers worry a great deal about H5N1, because they fear reassortment could help it mutate to pass between people. This 2011 article from the Los Angeles Times explains some background about H5N1 and controversial scientific efforts to study its potential to create a pandemic. Updates about H5N1 research are available here, here, here and here.)
The UCLA-based research team, which also included scientists from Belgium, China and Egypt, looked at reports of cases of H3N2 in people and H5N1 in birds to see where both were high in a particular area. They also looked at how many pigs were present (because they can host co-infections of both flus) in some regions of interest and at other factors such as human, duck and chicken population density.
The flu surveillance wasn't always robust, but in the end, they found coastal and central China and the Nile Delta -- as well as major cities in India, Japan and Korea -- all could have the right mix of flu strains and other conditions to permit the H3N2 and H5N1 viruses to exchange genetic material and spawn a dangerous influenza.
That could give public health workers hoping to prevent a pandemic some ideas where to focus their efforts, said study senior author and UCLA professor Thomas Smith.
"These findings predicting potential outbreak sites can help decision-makers prioritize the most important areas where people, poultry and livestock should be vaccinated and animals should be monitored for novel viruses," he said.
Follow me on Twitter: @LATerynbrown