During the past 100 years, life expectancy more than doubled in developed countries. In the last few decades, however, thirty new infectious diseases have emerged and one of them — AIDS — is becoming perhaps the most devastating epidemic in history. New diseases travel the globe with unprecedented rapidity, and older killers that once seemed controllable are roaring back with a vengeance. How Safe Are We? examines the most critical threats we face today — including avian flu — and the pressing need to strengthen global public health systems.