(Xinhua)
Updated: 2007-12-14 11:28

Two cases of bird flu in humans involving family members in Nanjing, Jiangsu Province, have been effectively contained, China's Ministry of Health announced. It added all close contacts involved had been released from medical observation.

"None of those in close contact showed unusual symptoms and they were all released from medical observation on December 12," the ministry said in a statement posted at its Website (www.moh.gov.cn) on Thursday.

China announced on December 2 that a 24-year-old man surnamed Lu in the provincial capital Nanjing died of H5N1 infection. On December 7, the man's father was also confirmed to be infected with the virus.

Eighty-two people who had contact with either man were put under close medical observation.

"The father, who has been under intensive medical treatment, is in stable condition and showing signs of improvement," the ministry said in the statement.

Neither men was said to have known contact with sick or dead poultry and so far the source of the infection remained unknown.

Mao Qun'an, spokesman of the Health Ministry, said earlier that there were several possibilities for infection in the second case, including close contact between the father and the son. It was also possible that both men were either infected by the same source or separately by different sources.

Joanna Brent, a Beijing-based the WHO spokeswoman, told Xinhua that "there is no strong indication of human-to-human transmission. But because this possibility cannot be ruled out, the WHO is monitoring this case closely."

"If this (the second case) was proved to be a case of human-to-human transmission, it seems likely that the transmission is inefficient since, so far, there is just one confirmed case out of 83 close contacts and the two cases were directly related, with no second-generation transmission," she said.

She also said that at this stage a possible common source has not been identified and based on preliminary laboratory results of these two cases, the possibility of infection from two separate sources is least likely.

Brent said that like most H5N1 cases in China, these cases were not foreshadowed by a poultry outbreak reported to the Ministry of Agriculture. "This suggests that strategies for monitoring H5N1 in poultry need further strengthening," she said.

China's Ministry of Health said that local health authorities had tightened monitoring of pneumonia cases over the past 10 days and collected a large number of samples. "All samples tested (H5N1) negative and no suspected or unusual cases were discovered, " it said.

The latest cases bring the number of confirmed bird flu cases in humans in China to 27 since 2003. During that period, there have been 17 deaths.