HANOI, Vietnam - One of the many mysteries of bird flu is that it has not infected more people like Ha Thi Quynh.
Quynh and the others at Hanoi's largest poultry market, Long Bien, say they're living proof that bird flu is hard for people to catch. They work without fear or protective gear in a place where fresh blood runs through open gutters. They say not a single person from the market has ever gotten sick or died from the H5N1 bird flu virus.
Researchers agree. They're just not sure why these people have stayed healthy.
Dr. Jeremy Farrar, director of Oxford University's clinical research unit at the Hospital for Tropical Diseases in Ho Chi Minh City, theorized that "it may be ... because of the nature of the way that people prepare chickens in their houses. It could be because there's some difference in the immune response between younger people and older people."
Farrar was part of a large research committee that reported in the New England Journal of Medicine last month what's known about those infected with bird flu. The youth of most of the virus' victims was striking.
The researchers also noted that recent infections have caused "high rates of death among infants and young children."
The paper says most victims were those who plucked and prepared sick birds, handled and groomed fighting cocks, played with birds, or ate raw duck blood pudding or possibly undercooked meat.
Farrar said it's possible some people could have a pre-existing immunity protecting them, but there has been no research to prove that. He also said the type of contact between people and poultry could play a role.
