Fishermen drag a net in Lake Malawi in 2012. About the size of New Jersey, the lake is home to hundreds of fish species and is considered one of the most biologically diverse lakes in the world.
Dr. Lisa Sterman held a Truvada pill at her office in San Francisco in 2012. She prescribed Truvada to patients at high risk for HIV infection even before the Food and Drug Administration approved the medicine explicitly for that purpose.
A farmworker in Riyadh, Saudi Arabia, wears a mask to protect against Middle East respiratory syndrome earlier this month. The MERS virus is common in camels.
Fayez Nureldine/AFP/Getty Images
An Egyptian Muslim prays during a ritual in Mina, Saudi Arabia, October 2013. Some people wore masks during the hajj pilgrimage last year to protect against the Middle East Respiratory Syndrome.
Rose Komano, 18 and the mother of three, was the first Ebola patient to overcome the virus in southeastern Guinea, the epicenter of the outbreak. On April 3, she posed at a health clinic in the Gueckedou region.
Misha Hussain /Reuters /Landov