Bird flu is highly lethal to some animals, but not to others. Scientists wants to know why

Scientists are trying to determine why bird flu kills some animals quickly but leads to mild illnesses in others. In the last two years, the virus has been blamed for the deaths of millions of wild and domestic birds worldwide. It’s killed legions of seals, wiped out mink farms, and dispatched cats, dogs and even a polar bear. But it seems to have hardly touched people. And, as it spreads in U.S. dairy cows, it seems to be causing relatively few severe illnesses. Scientists are exploring what’s behind the differences — and whether the situation will change. Scientists are trying to determine why bird flu kills some animals quickly but leads to mild illnesses in others. In the last two years, the virus has been blamed for the deaths of millions of wild and domestic birds worldwide. It’s killed legions of seals, wiped out mink farms, and dispatched cats, dogs and even a polar bear. But it seems to have hardly touched people. And, as it spreads in U.S. dairy cows, it seems to be causing relatively few severe illnesses. Scientists are exploring what’s behind the differences — and whether the situation will change.  AP Technology and Science