The man went to a hospital in Shenzen on Dec. 21 and tested positive for bird flu, caused by the highly contagious H5N1 virus, the BBC reported.
Regional health officials said the man was a bus driver who hadn't had any direct contact with live poultry or other birds and hadn't traveled outside the city.
The same day the man was hospitalized, nearby Hong Kong ordered 17,000 chickens culled after one at a market tested positive for the virus, which has a 60 percent human mortality rate, CNN reported.
Officials said they had so far been unsuccessful at tracking where the infected bird originated.
World Health Organization statistics indicate 573 people are known to have been infected with H5N1, of which 336 died since 2003. The peak of infections was in 2006 and affected 63 countries.
Health officials say the virus also infects migratory birds such as ducks and geese, making containment difficult.