A man in eastern China has contracted what might be the world’s first human case of the H10N3 strain of bird flu, but the risk of large-scale spread is low, the government said Tuesday.

The 41-year-old man in Jiangsu province, northwest of Shanghai, was hospitalized on April 28 and is in stable condition, the National Health Commission (NHC) said on its website. He was diagnosed as having the H10N3 avian influenza virus on May 28, it said, but did not give details on how the man had been infected with the virus.

"This infection is an accidental cross-species transmission," its statement said, according to remarks carried by The Associated Press (AP). "The risk of large-scale transmission is low."

It described H10N3 as low pathogenic – less likely to cause death or severe illness – in birds. The NHC said there had been no human cases of H10N3 previously reported in the world. Several strains of bird flu have been found among animals in China but mass outbreaks in humans are rare.

The strain is "not a very common virus," said Filip Claes, regional laboratory coordinator of the Food and Agriculture Organization's Emergency Centre for Transboundary Animal Diseases at the regional office for Asia and the Pacific. Only around 160 isolates of the virus were reported in the 40 years prior to 2018, mostly in wild birds or waterfowl in Asia and some limited parts of North America, and none had been detected in chickens so far, he added.

The last human epidemic of bird flu in China occurred from late 2016 to 2017, with the H7N9 virus.

Analyzing the genetic data of the virus will be necessary to determine whether it resembles older viruses or if it is a novel mix of different viruses, Claes said. Many different strains of avian influenza are present in China and some sporadically infect people, usually those working with poultry. There have been no significant numbers of human infections with bird flu since the H7N9 strain killed around 300 people during 2016-2017.

Following recent avian flu outbreaks in Africa and Eurasia, the head of the Chinese Center for Disease Control and Prevention (CCDC) last week urged stricter surveillance in poultry farms, markets and of wild birds. COVID-19 was first detected at a food and animal market in the central Chinese city of Wuhan in late 2019.