Sharjah24 – Reuters: A jump in the number of people in China infected with bird flu this year is raising concern among experts, who say a previously circulating strain appears to have changed and may be more infectious to people.

China has reported 21 human infections with the H5N6 subtype of avian influenza in 2021 to the World Health Organization (WHO), compared with only five last year, it said.

Though the numbers are much lower than the hundreds infected with H7N9 in 2017, the infections are serious, leaving many critically ill, and at least six dead.

"The increase in human cases in China this year is of concern. It's a virus that causes high mortality," said Thijs Kuiken, professor of comparative pathology at Erasmus University Medical Centre in Rotterdam.

Most of the cases had come into contact with poultry, and there are no confirmed cases of human-to-human transmission, said the WHO, which highlighted the rise in cases in a statement on Oct. 4.

It said further investigation was "urgently" required to understand the risk and the increase in spill over to people.