Next Up, Locusts: Bird Flu Closes In on Humans

A new mutation of bird flu virus H5N1 allows it to survive in humans, which have cooler body temperatures than birds. The virus doesn’t currently transmit between humans, but the ability to survive in our respiratory tract could start an epidemic, researchers warn. "I don't like to scare the public, but it is important to the scientific community to understand what is happening," said one.

The virus has infected 329 people since 2003, killing 201 of them, Reuters reports, a mortality rate that would make for a global epidemic far worse than the 1918 flu. But scientists caution that the viruses are constantly evolving and that they “don't know how many mutations are needed for them to become pandemic strains." (More avian flu stories.)