Control of infectious diseases has resulted from clean water and better sanitation. Infections such as typhoid and cholera, major causes of illness and death early in the 20th century, have been reduced dramatically by improved sanitation. However, many diseases thought to have been conquered are making a resurgence in the developing world. In addition, new diseases threaten to emerge wreaking large-scale havoc on human populations. Infectious diseases studied by our faculty include pandemic influenza, hospital-acquired infections, and the spread of Methicillin-resistant Staphylococcus aureus (MRSA) between people and their pets.