Scientists fear bird flu has spread from mammals to humans for the first time, marking another step in the evolution of the deadly virus.
New analysis concludes there is “strong evidence” that a Texas farm worker who tested positive for the H5N1 virus caught it from sick dairy cattle.
Although there have been other people infected with the virus in recent years – including some who have died – they all acquired it from birds.
There is growing concern about the failure of American authorities to contain the spread of the virus.
So far 36 herds in nine states have tested positive. But testing of milk has suggested the virus has spread far more widely.
The longer it spreads unchecked in a domesticated mammal, the greater the chance of it becoming adapted to a new species – and being passed on to humans who have close contact.
According to the report in The New England Journal of Medicine, the unidentified man’s symptoms were mild. He developed the eye infection conjunctivitis but had no fever and no trouble breathing. His lungs were also clear.
He and the people he lived with were given antiviral drugs as a precaution. Nobody else became ill.
The team, which included researchers from the Centres for Disease Control, said: “Given the infected human was a dairy farm worker with reported exposure to sick, presumably infected cows in Texas and without reported exposure to other mammals or birds, we believe the genetic and epidemiological data are strong evidence of infection of the human following exposure to presumably virus-infected cows.”
Some mammals infected
The highly pathogenic strain of H5N1 has been…
