A police officer is silhouetted through the emergency room door at a public hospital in San Pedro Sula, Honduras. With 91 murders per 100,000 people, the Central American nation is often called the most violent in the world. The homicide rate is roughly 20 times that of the U.S. rate, according to a 2011 U.N. report. Esteban Felix/AP hide caption
Health workers suit up for Ebola duty in Monrovia, Liberia. John W. Poole/NPR hide caption
In November, the Ebola virus found in Mali was surprisingly similar to strains circulating in Sierra Leone six months earlier. Courtesy of NIAID hide caption
Two drops of polio vaccine are administered to a child in a Nigerian health clinic. David Gilkey/NPR hide caption
Kpetermeni Siakor (left), a Liberian who is studying in Ghana, used crowdsourcing software to help out during the Ebola epidemic. Courtesy of Ashesi University College hide caption
No thumping required: Ketchup easily slides out of a glass bottle treated with LiquiGlide. Screengrabs from LiquiGlide hide caption
Safe and small: The credit-card-sized test for anthrax destroys the deadly bacteria after the test completes. Courtesy of Sandia Nation hide caption
Maria Carmen Castro, 46, of Lima, Peru, is a survivor of MDR-TB — multidrug-resistant tuberculosis. Partners In Health treated her and loaned her money to open a small store. "Because of my TB and thanks to God and Partners In Health, now I have my own business," she says. Jason Beaubien/NPR hide caption
It's not the real deal. This Ebola Treatment Unit was set up for a TED talk in Vancouver so people could get a sense of what the units are like, and what it's like to put on the protective suit. Nina Gregory hide caption
Light shines through the chlorine-stained windows in the blood-testing area at Redemption Hospital in New Kru Town, Monrovia, Liberia. David Gilkey/NPR hide caption
Polina, 37, rests in a hospital bed in St. Petersburg, Russia, in 2011. She is severely malnourished and suffers from numerous diseases, including tuberculosis, hepatitis C and HIV. Misha Friedman hide caption
Liberians lay wreaths in memory of those cremated due to the deadly Ebola virus in Disco Hill, Margibi County, Liberia, earlier this month. Ahmed Jallanzo/EPA/Landov hide caption
Twins Watta and Fatta Balyon pose outside the home of their guardian Mamuedeh Kanneh in Barkedu, a village in Liberia. John W. Poole/NPR hide caption
The European Union banned the use of antibiotics to boost animals' growth in 2006. At first, the ban had little effect on the amount of drugs given to pigs. Carsten Rehder/Corbis hide caption