A middle-aged man who transported poultry for a living and another unidentified person have died from a new strain of bird flu, bringing the death toll to five among 14 confirmed cases in China, the government and state media reported Thursday.

The 48-year-old man, who died in Shanghai, is one of several among the infected believed to have had direct contact with fowl. Until recently, the virus, called H7N9, was not known to infect humans.

The official Xinhua News Agency did not identify the fifth fatality, but said that person also died in Shanghai on Wednesday.

It said the Ministry of Agriculture confirmed on Thursday that the H7N9 virus had been detected in pigeons at a market selling agricultural products in Shanghai.

It is not known how people are becoming sick with the virus, and health officials and scientists caution that there are no indications it can be transmitted from one person to another. Scientists who have studied the virus's genetic sequence said this week that the virus may have mutated, spreading more easily to other animals and potentially posing a bigger threat to humans.

Guidelines issued Wednesday by the national health agency identify butchers, breeders and sellers of poultry, and those in the meat processing industry as at higher risk.

Experts only identified the first cases on Sunday. Some among the 14 confirmed cases fell ill several weeks ago but only now are being classified as having H7N9.

Xinhua said six cases have been confirmed in Shanghai, four in Jiangsu, three in Zhejiang and one in Anhui. (AP)