China said Friday none of the people who had come into close contact with the two most recent cases of bird flu — a young man who died and his infected father — had contracted the virus.

The 82 people who had close contact with the two were all released from medical observation Wednesday after they showed no unusual symptoms, health ministry spokesman Mao Qun'an told AFP.

The dead man, a 24-year-old surnamed Lu, died from avian flu on December 2. His 52-year-old father was confirmed a few days later to have also contracted the H5N1 strain of the virus.

The father was now in a stable condition and showing signs of improvement, according to a health ministry statement on its website.

The father-son case, in the eastern province of Jiangsu, raised concerns of possible human-to-human transmission, and the authorities' latest announcement seemed targeted at easing those fears.

The health ministry said Monday that there was no evidence the father had contracted the disease from his son and there was no reported outbreak of the disease among poultry.

However, exactly how the virus transmitted in their case remains unknown, because the son is not thought to have had any contact with dead poultry and authorities said there had been no bird flu epidemic locally.

This followed a familiar pattern in China where humans have contracted the disease in an area where there have been no reported outbreaks among poultry.

The father-son case has brought reports of human cases of bird flu in China to 27 since 2003. Seventeen of those people have died.