Smoke rises from chimneys of coal-based power plants in the Sonbhadra District of Uttar Pradesh, India. The Washington Post/Getty Images hide caption

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Burmese migrant Thazin Mon Htay and her father Ko Ngwe Htay were trafficked to Thailand to peel shrimp. They worked 16-hour shifts, seven days a week, for less than $10 a day, Ko Ngwe told PBS NewsHour. Jason Motlagh/Pulitzer Center on Crisis Reporting for NPR hide caption

itoggle caption Jason Motlagh/Pulitzer Center on Crisis Reporting for NPR

The rapid Ebola test from Corgenix Medical Corporation is small and easy to use. But because it involves blood, health workers would still need to run the test at a lab to stay safe. Courtesy of Corgenix Medical Corp. hide caption

itoggle caption Courtesy of Corgenix Medical Corp.

A health worker with Doctors Without Borders carries a child suspected of having Ebola at the treatment center in Paynesville, Liberia, last October. Ebola is especially deadly for young children and babies. About 4 in 5 infected died. John Moore/Getty Images hide caption

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You want that soda bottle. But it may not be because you crave soda. It might just be that you love the idea of wrapping your fingers around its enticing shape. Ariel Zambelich/NPR hide caption

itoggle caption Ariel Zambelich/NPR

Dr. Kwan Kew Lai volunteered for six weeks at an Ebola treatment center run by International Medical Corps in Bong, Liberia. Courtesy of Kwan Kew Lai hide caption

itoggle caption Courtesy of Kwan Kew Lai

Random violence in Syria makes it a dangerous place for aid workers. This month, members of the Syrian Arab Red Crescent transported Syrians from a rebel area to a part of Aleppo controlled by the Assad regime. Baraa Al-Halabi/AFP/Getty Images hide caption

itoggle caption Baraa Al-Halabi/AFP/Getty Images

This World Health Organization map shows the percent of the population vaccinated for measles in each country in 2013. Dark green is at least 90 percent. Light green is 80 to 89 percent. Orange is 50 to 79 percent. Red is less than 50 percent. Courtesy of WHO hide caption

itoggle caption Courtesy of WHO

Dr. Margaret Chan, director-general of the World Health Organization, has said of Ebola: "It overwhelmed the capacity of WHO, and it is a crisis that cannot be solved by a single agency or single country." Fabrice Coffrini/AFP/Getty Images hide caption

itoggle caption Fabrice Coffrini/AFP/Getty Images

The number of children who need glasses has risen quickly across East Asia and Southeast Asia. But some parents and doctors in China are skeptical of lenses. They think glasses weaken children's vision. Imaginechina/Corbis hide caption

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Writer Roald Dahl and his wife, actress Patricia Neal, with two of their children, Theo and Chantel Sophia "Tessa." The photo was taken a few years after oldest daughter, Olivia, died of measles. Hulton Archive/Getty Images hide caption

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A nurse administers an experimental Ebola vaccine Monday at Redemption Hospital in Monrovia, Liberia. Researchers aim to give shots to 27,000 people during the large trial. John Moore/Getty Images hide caption

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Can you find Australia and Canada? The cartogram scales each country's geographic area by its population. (Click through to see a high-resolution map.) Original work courtesy of Paul Breding. Copyright 2005, ODTMaps.com, Amherst, MA. Adapted by Reddit user TeaDranks hide caption

itoggle caption Original work courtesy of Paul Breding. Copyright 2005, ODTMaps.com, Amherst, MA. Adapted by Reddit user TeaDranks

An employee of the drug company Apotex, examines some Ciprofloxacin at the plant in Canada. Cipro is commonly given to travelers for diarrhea. More than 20 million Cipro doses are prescribed each year in the U.S. Getty Images hide caption

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Cellphones are everywhere in the developing world, as this Nairobi street scene shows. Bill and Melinda Gates believe the phones can be used for everything from farmer education to instant banking. Simon Maina/AFP/Getty Images hide caption

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In November, women in El Salvador marched for the freedom of 17 women accused of abortion, including Carmen Guadalupe Vasquez Aldana. She was pardoned this week. Luis Galdamez/Xinhua /Landov hide caption

itoggle caption Luis Galdamez/Xinhua /Landov

After the earthquake in 2010, about 1,000 people were living in tents on the median of Highway 2, one of Haiti's busiest roads. Five years later, tens of thousands of people in Port-au-Prince still live in tents and other temporary housing. David Gilkey/NPR hide caption

itoggle caption David Gilkey/NPR

Ecologists found signs of Ebola in a Rousettus leschenaultii fruit bat. These bats are widespread across south Asia, from India to China. Kevin Olival/EcoHealth Alliance hide caption

itoggle caption Kevin Olival/EcoHealth Alliance