Bird Flu Takes Flight

Winter in the northern hemisphere means one chilling thing for global health officials: it's bird-flu season. Nine countries have announced outbreaks in recent weeks, and infections are expected to accelerate as temperatures drop and migratory birds carry the virus to new areas. A replay of 2006—when H5N1 killed 80 people and spread to the Middle East and Africa—could well be on the way. Worst-case scenario: the virus might mutate and become easily transmissible among humans, potentially triggering a global pandemic. "Like last year's bird-flu season," says WHO spokesman Peter Cordingley, "this year could be very uncomfortable." Here's a look at some...