Exterminator: Stopping the World's Most Infectious Diseases

Germs--bacteria, viruses, and other organisms--surround us. While some germs are good, others are downright nasty. Germs cause infectious illnesses from the common cold to mad cow disease. Drugs and vaccines have wiped out deadly diseases such as smallpox. Still, we face new infectious enemies every day. Find out how medical researchers are working to win the battle.