Bird flu: father infected by dying son Alarm about a flu pandemic has been restarted by clear evidence that bird flu, which is rife in the Far East, can be transmitted person to person. This could be one of the first steps in the evolution of the H5N1 strain of avian flu into a deadly pandemic strain that could infect hundreds of millions of people. The new evidence involves a 52-year-old man who caught the disease from his 24-year-old son, who himself seems to have picked it up at a poultry market. The son died, while his father narrowly survived. A team of doctors led by Yu Wang, of the Chinese Centre for Disease Control and Prevention in Beijing, report in The Lancet online that the two cases of avian flu were detected in the family from Nanjing, in Jiangsu Province, in December last year. The man of 24, a salesman, developed fever, chills, headache, a sore throat and a cough. He was treated with antibiotics but his condition worsened and he was admitted to hospital, where he died five days later. Just before he died, tests showed that he was infected by H5N1 avian flu virus. His father, a retired engineer, lived six miles away. When his son fell ill he went to see him and helped to look after him in hospital for two days. The father fell ill a week later but survived after being treated with antiviral drugs and blood plasma from a woman who had been deliberately infected with inactive H5N1 in a clinical trial. He spent 22 days in hospital. Samples of H5N1 virus taken from the father and son were genetically identical, save for one small change. Flu virus mutates rapidly, so the fact that these two samples were so nearly identical is strong evidence of direct infection from son to father. Jeremy Farrar and colleagues from the Hospital for Tropical Diseases in Vietnam said in The Lancet: "If we continue to experience widespread, uncontrolled outbreaks of H5N1 in poultry, the appearance of strains well-adapted to human beings might be just a matter of time."