China's Bird Flu Might Someday Spread More Easily
For now, however, the virus doesn't transfer well from human to human, experts say
WebMD News Archive
By Steven Reinberg
THURSDAY, July 18 (HealthDay News) -- The deadly H7N9 bird flu virus has the potential to be easily transmitted from human to human, a new study suggests.
Chinese scientists have found that the virus is highly transmissible between ferrets, a mammal often used to study possible virus transmission between humans. This discovery could portend a time where the virus might become pandemic, the researchers added.
"The situation raises many urgent questions and global public health concerns," said study co-author Hualan Chen, director of the National Avian Influenza Reference Laboratory at Harbin Veterinary Research Institute.
So far, more than more 130 people in China have been infected with the H7N9 flu, and at least 37 have died, the researchers noted.
However, one U.S. expert stressed that it isn't known whether large-scale spread among humans will actually occur.
"We already know H7N9 can spread human-to-human," said Dr. Marc Siegel, an associate professor of medicine at NYU Langone Medical Center in New York City. "So far, however, we are not seeing large outbreaks. That's not an accident. You can see something in a test tube or in a ferret that doesn't reproduce in real life."
The new study shows that the H7N9 virus does not sicken poultry, Chen said. This can make the virus hard to track as it infects people, since they can be around infected birds without being aware of it.
Replication in humans, however, provides opportunities for the virus to acquire more mutations and become more virulent and transmissible in mammals, she explained.
"Our results suggest that the H7N9 virus is likely to transmit among humans, and immediate action is needed to prevent an influenza pandemic caused by this virus," Chen said.
The new report was published July 18 in the online edition of the journal Science.
The U.S. Centers for Disease Control and Prevention is keeping a close eye on the H7N9 virus.
"Anytime a new flu virus emerges, especially one that can cause severe disease in humans, it's a virus we get very interested in," said Dr. Joseph Bresee, chief of the epidemiology and prevention branch in the CDC's Influenza Division.
Bresee noted that, so far, the H7N9 virus does not spread easily from human to human, but it is still concerning.
"It can cause severe disease and deaths in humans. The one thing that gives us comfort so far is that it doesn't seem to be able to spread efficiently between humans and that's what allows a flu virus to develop into a pandemic virus," he said.
Not only is the CDC watching this virus, Bresee said: "The whole world is watching."
Within the United States, the CDC has told state health departments what to look for and how to test for H7N9, Bresee said.