Usman (right), 7 months, and Abdullah (left), 18 months, are held by their mothers while they wait to receive the polio vaccine at the Jalozai refugee camp near Peshawar, Pakistan.
Daniel Berehulak/Getty Images
Medical workers treat Ebola patients at the Eternal Love Winning Africa hospital in Monrovia, Liberia. Three workers at the hospital, including Dr. Kent Brantly (left), have tested positive for Ebola.
Courtesy of Samaritan's Purse
A health worker gives a child the polio vaccine in Bannu, Pakistan, June 25. More than a quarter-million children in Taliban-controlled areas are likely to miss their immunizations.
A. Majeed/AFP/Getty Images
Clear and clean, bubble wrap is well-suited to serve as an array of tiny test tubes. Here a dye solution is injected into the bubbles to measure the hemoglobin concentration in blood.
American Chemical Society
Dogs throughout Latin America carry the Chagas parasite — and boost the risk of people catching it. And it's not just shelter dogs, like these in Mexico, who are at risk. Even family dogs get the deadly disease.
Jose Luis Gonzalez /Reuters/Landov