CHINA - Scientists studying the H7N9 bird flu virus that has killed more than 40 people since March said Wednesday they had discovered another H7-type virus lurking in chickens in China.
Dubbed H7N7, the virus was able to infect mammals in a lab experiment, said the team, warning H7 viruses "may pose threats beyond the current outbreak".
"The continuing prevalence of H7 viruses in poultry could lead to the generation of highly pathogenic variants and further sporadic human infections," they wrote in the journal Nature.
According to the World Health Organisation (WHO), there have been 135 confirmed cases of people contracting H7N9 bird flu, of whom 44 died. All the cases were in China, except for one in Taiwan.
Earlier this month, Chinese scientists reported the first likely case of direct person-to-person transmission, but stressed the H7N9 virus, which jumps from birds to people, was not yet able to spread easily between humans.
The new work points to yet another viral threat.
"If (we) let this H7N7 continue circulating in chickens, I am sure that human infection cases will occur," study co-author Yi Guan from the University of Hong Kong told AFP by email.
"This virus could cause more severe infection than... H7N9, based on our animal experiment."