Son to father spread of bird flu panics experts

According to a top scientist at China's Centre for Disease Control, a man who died in December infected his father with the deadly H5N1 strain of bird flu before he died.

The revelation by Professor Yu Wang and colleagues, published in the current online edition of the Lancet, has prompted experts to renew calls for increased vigilance.

Experts have been concerned for a number of years that the H5N1 strain of the avian virus will eventually mutate into a form capable of being transferred between humans; this could potentially trigger a pandemic which could kill millions of people.

Apart from the odd case where scientists have suspected the transmission possibly occurred under very specific circumstances, the vast majority of the known 378 human cases were contracted by close contact with infected birds.

According to the World Health Organisation (WHO) since 2003 more than 60 percent of these cases have been fatal.

The 24-year old Chinese man, living in the city of Nanjing, in China's Jiangsu Province, had visited a poultry market six days before he became ill; he lived with his mother in an apartment six miles away from his father's house.

When he became ill his father nursed him in hospital and had very close contact with him.

Though the father was exposed to the fever, violent coughing and diarrhoea his son suffered, at no time was he exposed to poultry.

The 52-year-old father in turn also became ill with the virus but following drug treatment and blood transfusions he made a full recovery.

Experts suggest it was the extensive exposure to secretions from a person who was very sick in hospital and also a blood relative, which enabled the transmission to take place.

Professor Yu Wang and colleagues say of the 91 other people who came into contact with the son before he died, none have shown any sign of infection, nor was there any significant genetic variation between the viral strain in the father or the son.

Professor Wang says any new clusters of the virus demand urgent investigation because of the possibility that a change in the epidemiology of H5N1 cases could indicate that H5N1 viruses have acquired the ability to spread more easily among people.

The WHO says since 2003, there have been 107 H5N1 bird flu fatalities in Indonesia, 52 in Vietnam, 20 in China, 17 in Thailand, and under ten cases in seven other nations.