Second outbreak, with 318 human infections and 100 deaths, twice as big as first outbreak
WebMD News from HealthDay
By Dennis Thompson
WEDNESDAY, March 11, 2015 (HealthDay News) -- Avian flu, commonly called "bird flu," is gaining strength in China and has the potential to emerge as a life-threatening virus for humans across the globe, a new report suggests.
In the year since avian flu first surfaced in China, it has expanded throughout that country and become a persistent infection in chickens there, the new report states.
The virus also has begun to mutate in chickens, raising concerns that it could gain the ability to more easily infect humans and spread beyond China, the study authors warned.
"Therefore, H7N9 viruses should be considered as a major candidate to emerge as a pandemic strain in humans," Yi Guan, from the University of Hong Kong, and colleagues concluded in the March 11 issue of the journal Nature.
Avian flu, also known as H7N9 influenza, first appeared in eastern China in March 2013 when the virus spread to humans from infected poultry, according to the U.S. Centers for Disease Control and Prevention.
A second wave of the H7N9 outbreak that began in late 2013 has resulted in at least 318 human infections and more than 100 deaths -- more than twice that of the first wave, the study authors said.
To better understand this second wave and predict its path, researchers monitored the evolution and spread of H7N9 over 15 cities across five provinces in China.
The researchers identified a large number of new genetic variants that have become established in chickens, and tracked the march of those viral mutations across the country as chickens were sold and transported.
"With the recent reports of H7N9 infections in Xinjiang in the far northwest of China, it is probable that the H7N9 virus is now present across most of China," the study authors wrote. "As this virus does not cause obvious symptoms in chickens and only limited surveillance has been conducted, the prevalence of this virus is likely to be higher than we document here," they added.
U.S. infectious disease experts said the new report out of China raises serious concerns.
source : Bird Flu Spreads Across China, Posing Threat to People: Report