Measles had virtually vanished from the United States. But thanks to the anti-vaccine movement, outbreaks have returned.
World Health Organization
Antibiotic resistance occurs when a bacteria, fungi, or parasite is no longer curable by medicines previously able to treat them.
How can you best protect yourself from the Zika virus?
The H7N9 virus has proven deadly in China, but it is not yet a pandemic.
It takes months of work from around the world to create a flu shot.