China has reported 21 cases of the H5N6 subtype of bird flu this year, compared with only five last year, leaving experts concerned that the strain currently circulating is more infectious than past versions of the virus, Reuters reported (opens in new tab).
Scientists first identified H5N6 avian influenza in poultry in Laos in 2013, according to a 2020 report in the journal Emerging Infectious Diseases (opens in new tab) (EID). And since 2014, a total of 49 confirmed cases of humans infected with H5N6 have been reported to the World Health Organization (WHO), according to the WHO's Avian Influenza Weekly Update (opens in new tab).
The 21 cases reported in China this year have resulted in at least six deaths and left many of the remaining infected people critically ill. "The increase in human cases in China this year is of concern. It's a virus that causes high mortality," Thijs Kuiken, a professor of comparative pathology at Erasmus University Medical Center in Rotterdam, Netherlands, told Reuters. According to the EID report, human H5N6 infections have a 67% mortality rate.
The WHO has confirmed that, among the 21 infected individuals in China, most came into contact with poultry, and there have been no confirmed cases of human-to-human transmission, Reuters reported.
"Currently available epidemiologic and virologic evidence suggest that A(H5N6) influenza viruses have not acquired the ability of sustained transmission among humans, thus the likelihood of human-to-human spread is low," a WHO spokesperson told BNO News (opens in new tab) on Oct. 5. The spokesperson also stated that wider geographical surveillance of affected areas in China and nearby regions is "urgently required" to understand the recent uptick in human cases.
It could be that the H5N6 currently circulating is a new variant that infects humans more easily than past versions of the virus, Kuiken told Reuters. Or there may be a significant increase in H5N6 among poultry, which could result in more human exposure to the virus.
Originally published on Live Science.