Cats can become sick with Avian flu by being fed virus-infected chickens or just by having contact with domestic or wild birds with the illness. Once infected, cats then excrete the virus from the respiratory and digestive tract, sometimes transmitting the flu to other cats, according to scientific commentary in this week's Nature magazine.
The commentary examines mounting reports of cats dying from Avian flu, or H5N1, and why cats are vulnerable. The first reported feline death was in Thailand in 2004, but since then 147 captive tigers had to be euthanized after being fed virus-infected chicken carcasses.
In this case, the tigers contracted the flu directly through the gut, which according to Nature, is a novel route for flu transmission in mammals. For this reason, the scientists argue that organizations like the World Health Organization may be overlooking the role of cats in the spread of the flu.