Loved ones express their grief at the burial of Ramon Romero Ramirez in Chichigalpa, Nicaragua, January 2013. The 36-year-old died of chronic kidney disease after working in the sugar cane fields for 12 years. Ramirez is part of a steady procession of deaths among cane workers. Ed Kashi/VII hide caption
Fearful of catching the MERS virus, workers wear masks during a soccer match on April 22 at King Fahad stadium in Riyadh. Fayez Nureldine/AFP/Getty Images hide caption
There today, here tomorrow: A mother holds her child for a measles vaccination in Manila, Philippines, in January. Travelers are bringing measles from the Philippines to the United States. Noel Celis/AFP/Getty Images hide caption
By ensuring vaccines are invented and distributed, Bill Gates says, his foundation is dramatically reducing the number of childhood deaths in poor countries. Marie McGrory/NPR hide caption
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. Amr Nabil/AP hide caption
Gado Labbo holds her 5-year-old son, Yusuf, at a clinic in Dareta, Nigeria. In 2010, when Yusuf first entered the clinic, he had a blood lead level 30 times higher than the amount the Centers for Disease Control and Prevention considers dangerous. David Gilkey/NPR hide caption
Chemist Facundo Fernandez of the Georgia Institute of Technology tested morning-after pills collected from 15 different pharmacies in Lima, Peru. Rob Felt/Georgia Tech hide caption
Potent but not perfect: Medical assistant Elissa Ortivez prepares a measles, mumps and rubella vaccine at a clinic in Walsenburg, Colo. John Moore/Getty Images hide caption
A child receives a polio vaccine Sunday in Kano, Nigeria. The country is the primary source of the virus in Africa but appears to be making progress against the disease; the current outbreak in Cameroon that has spread to Equatorial Guinea came by way of Chad, not Nigeria. Sunday Alamba/AP hide caption
In this colored transmission electron micrograph, an infected cell (reddish brown) releases a single Ebola virus (the blue hook). As it exits, the virus takes along part of the host cell's membrane (pink, center), too. That deters the host's immune defenses from recognizing the virus as foreign. London School of Hygiene & Tropical Medicine/Science Source hide caption
Testing for Ebola, a scientist in a mobile lab at Gueckedou, Guinea, separates blood cells from plasma cells to isolate the virus's genetic sequence. Misha Hussain/Reuters /Landov hide caption
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 hide caption
Not nice: A gut-eating amoeba (green) nibbles on a live human cell (purple) under the microscope. The parasite chews on the cell before killing and discarding it. Courtesy of Katy Ralston hide caption
Advocates demonstrate in favor of cheaper generic drugs to treat hepatitis C in New Delhi on March 21. The disease is common among people who are HIV positive. Saurabh Das/AP hide caption
The new normal in Guinea is washing hands with a mixture of water and bleach--shown here at the border entrance of Buruntuma, in the Gabu area on Tuesday. Tiago Petinga/EPA /LANDOV hide caption