The risk of human-to-human transmission of the bird flu virus exists, said a top Chinese medical expert on Wednesday.

The risk will increase if influenza viruses, such as those involved in the recent outbreak of flu in north China, combine with bird flu virus strains, said Zhong Nanshan, a renowned medical expert and academician with the Chinese Academy of Engineering.

Scientists said two pigs on the Indonesian island of Bali had produced a variation of the bird flu virus after they contracted bird flu. The pigs acted as a kind of mixing vessel in which genetic material from avian flu viruses combined with influenza strains.

Because some pig organs are similar to human organs, a similar risk could not be discounted where humans are concerned, said Zhong.

The best way to prevent bird flu is to dispose of infected birds as quickly as possible, establish stringent quarantine requirements and treat human patients rapidly, said Zhong at a China-Japan infection prevention conference in Guangzhou.

So far 269 people around the world have contracted bird flu and 163 of them have died, a mortality rate of over 60 percent, said Zhong.

In China, 22 people have contracted the virus and 14 died.

A 37-year-old farmer named Li from Tunxi in east China's Anhui Province contracted the H5N1 strain of bird flu in December -- the first human case reported on the Chinese mainland this winter.

After being treated in hospital for symptoms of fever and pneumonia, he was discharged on Jan. 6, according to the Ministry of Health.

Hundreds of thousands of people have been affected by ordinary flu this month in north China's Beijing and Tianjin municipalities but it is expected that the number of infections will soon drop.

The December-January period is a peak period for influenza in north China. Northeast China's Jilin and Heilongjiang provinces, and northwestern Gansu and Shaanxi provinces have also seen a spike in influenza cases.

(Xinhua News Agency January 25, 2007)