New Bird Flu No Immediate Threat: U.S. Experts
There's been no clear evidence of human-to-human transmission in Chinese outbreak
WebMD News Archive
By Amanda Gardner
TUESDAY, April 9 (HealthDay News) -- At this point, there's no reason to believe that the emerging H7N9 strain of bird flu that has sickened at least 24 people and killed seven in China is cause for alarm, health officials in the United States say.
For one thing, no cases of human-to-human transmission of the virus have yet been reported -- a necessary precursor to a full-blown pandemic.
"This is very early in the course of identification of human cases," said Dr. John Midturi, assistant professor of internal medicine at the Texas A&M Health Science Center College of Medicine, in Temple.
"We do see something similar every few years with avian [bird] flu," added Richard Webby, a member of the department of infectious diseases at St. Jude's Children's Research Hospital in Memphis.
But this year's strain does seem a little different.
"What's making everyone a little bit more uneasy is that, looking at the sequence of the virus, it appears to have some mutations we think may indicate that the virus might have increased its ability to replicate in humans," Webby said.
But for now, there's no proof of that ability, he cautioned, and the genetic sequence of the virus would still need to change for it to pass easily from person to person.
The first human cases were not identified until March 31, according to published reports.
It's possible that the H7N9 virus is also found in some type of mammal, such as swine, and public-health officials are working to identify possible hosts.
"We don't think that necessarily just this virus growing in [birds] would cause some of these [genetic] changes," said Webby, who's also director of the World Health Organization Collaborating Center for Studies on the Ecology of Influenza Viruses in Lower Animals and Birds. "We can't say with any sort of gusto that the last host of this virus was an avian host. Avian flu is a very generic sort of term.
Chinese authorities are taking precautions against further spread of the virus, suspending sales of live poultry in Shanghai and slaughtering poultry in markets where the virus has been detected.