EVANSVILLE, Ind., Aug. 26 (UPI) -- A handful of Midwestern scientists are quietly hunting in an unlikely place for the next pandemic flu virus capable of killing thousands of people -- the swine barns at county fairs.
Scientists believe that all of the deadly influenza outbreaks in human history probably originated in domesticated pigs. But they don't understand exactly how the virus transforms from a swine disease into something that can infect humans.
That makes it difficult to predict when it could happen again.
"We may have one right under our noses right now, but we don't know it," said Andrew Bowman, a professor of veterinary preventive medicine at the Ohio State University, who is leading the effort to identify and monitor flu strains in county fair pigs. "That is part of the reason we are doing this research."
Deadly influenza pandemics hit about four times a century, said Richard Webby, the director of the World Health Organization Collaborating Centre for Studies on the Ecology of Influenza in Animals and Birds at St. Jude Children's Research Hospital in Memphis, Tenn.
The last such pandemic occurred in 2009, when the previously unknown H1N1 virus emerged in pigs in Mexico and crossed into the human population. It spread quickly. The Centers for Disease Control and Prevention estimates that virus killed between 150,000 and 575,000 people worldwide.
The virus -- and its swine origin -- caught everyone by surprise, Bowman said.
"Prior to 2009, we were looking mostly at bird flu," Bowman said. "All the flu experts would have said that H1N1 strain would not be likely to be our next pandemic. We were all wrong. So, we had to reinvent the game, and start looking at pigs."
So researchers in the United States and around the world began to focus their efforts on understanding how the flu virus moves from pigs into humans.
Bowman launched the county fair monitoring project, with the aim is to track existing swine viruses, and sequence new ones.
"We use county fairs as a way to do surveillance efficiently," Bowman said. "County fairs bring a lot of animals from a wide geographical area to a single location."
Elsewhere, Webby's team at St. Jude's began to monitor large commercial hog operations. The U.S. Department of Agriculture started its own surveillance program. And other veterinary researchers began looking in the opposite direction -- tracking viruses that move from people to pigs.
"We already knew the virus could transfer from humans to pigs," said Daniela Rajao, an assistant professor at the College of Veterinary Medicine at the University of Georgia. "I was looking at the spread of viruses from humans to pigs before the 2009 pandemic.
"And then, once the 2009 pandemic hit, the dynamic between the two became even more complex because it was being transferred back and forth."
The data collected from these various projects is shared with researchers all over the world. And over the last decade, scientists have uncovered several markers they believe make a virus more likely to cross species.
Using those markers, the World Health Organization monitors data gathered by independent researchers around the world looking for viruses that my make the jump. When they find one, the agency commissions one of its collaborative centers to make a "seed vaccine" -- the starter that manufactures use to mass produce a vaccine.
"That seed vaccine takes time to make," Webby said. "So if we think there is a potential that a virus could spread, we make the seed vaccine. At least then it takes a few weeks off the time it takes to start circulating a vaccine if the virus does become pandemic."
Meanwhile, scientists like Bowman continue looking for what causes viruses to hop species.
"All the major pandemics start in the animal population," Bowman said. "We only know about them after the fact. The questions is: Can we know about them before? Because if we know ahead of time we can get vaccines ready and maybe stop a pandemic from happening."