Two people in the central Chinese province of Henan have been infected by a new strain of avian influenza, the first cases found in the region and bringing the total number nationwide to 51, Xinhua state news agency said on Sunday.
One of the victims, a 34-year old man in the city of Kaifeng, is now critically ill in hospital, while the other, a 65-year old farmer from Zhoukou, is stable. The two cases do not appear to be connected.
A total of 19 people in close contact with the two victims were under observation but had shown no signs of infection, Xinhua said.
On Saturday, the China Centre for Disease Control and Prevention confirmed that a seven year-old child in the capital of Beijing had been infected by the H7N9 bird flu virus, the first case to be reported outside of eastern China, where the new strain emerged last month.
The child's parents work in the poultry trade.
Investigators are trying to ascertain the source amid fears that it could cause a deadly pandemic similar to Severe Acute Respiratory Syndrome (SARS) in 2003, which killed about one in 10 of the 8,000 people it infected worldwide.
But authorities say there is still no indication of human-to-human transmission of the virus, which has already killed 11 people in Shanghai and the provinces of Zhejiang, Jiangsu and Anhui.