A woman receives the rVSV-ZEBOV Ebola vaccine at a clinical trial in Conakry, Guinea. The vaccine appears effective after only one shot. Cellou Binani/AFP/Getty Images hide caption

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Slum dwellers near Calcutta get their water from a municipal pipe. Water coming out of the tap on the left is for bathing and so is untreated. The blue Zimba chlorinator is hooked up to the tap on the right, which is used for drinking water. Courtesy of Suprio Das/Zimba hide caption

itoggle caption Courtesy of Suprio Das/Zimba

A family receives treatment for cholera at a clinic run by Doctors Without Borders in Port-au-Prince, Haiti, in October 2011, a year after the overwhelming outbreak began. Ramon Espinosa/AP hide caption

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Russia has strict rules on dispensing painkillers. Family members say some cancer patients killed themselves because they could not obtain the medicine and the pain was too great. Andy Baker/Ikon Images/Getty Images hide caption

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Health workers wash their hands after taking a blood sample from a child to test for the Ebola virus. On Tuesday, the workers tested people in the village outside Monrovia where a 17-year-old boy died of the disease over the weekend. Abbas Dulleh /AP hide caption

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The outbreak of Middle East respiratory syndrome is slowing down in South Korea, but people were still wearing surgical masks around Seoul on Monday. Ed Jones/AFP/Getty Images hide caption

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A police officer guards the home of a family under a 21-day Ebola quarantine in Freetown, Sierra Leone, back in March. Michael Duff/AP hide caption

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In front of the emergency room at the Samsung Medical Center in Seoul, medical workers care for a man suspected of having the Middle Respiratory syndrome on Monday. Jung Yeon-Je/AFP/Getty Images hide caption

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Primal posture: Ubong tribesmen in Borneo (right) display the perfect J-shaped spines. A woman in Burkina Faso (left) holds her baby so that his spine stays straight. The center image shows the S-shaped spine drawn in a modern anatomy book (Fig. I) and the J-shaped spine (Fig. II) drawn in the 1897 anatomy book Traite d'Anatomie Humaine. Courtesy of Esther Gokhale and Ian Mackenzie/Nomads of the Dawn hide caption

itoggle caption Courtesy of Esther Gokhale and Ian Mackenzie/Nomads of the Dawn

Patient one: A businessman brought the Middle East respiratory syndrome to South Korea in early May. Since then, he has likely spread the virus to more than 20 other people. Several of those have passed the virus onto others. Maia Majumder/Health Map hide caption

itoggle caption Maia Majumder/Health Map

Health workers collect the body of a cholera victim in Petionville, Haiti, February 2011. The cholera outbreak in Haiti began in October 2010. Nearly 9,000 people have died. David Gilkey/NPR hide caption

itoggle caption David Gilkey/NPR

Patients receive treatment at the Chest Disease Hospital in Srinagar, India. The country has one of the highest rates of drug-resistant tuberculosis in the world, in part because antibiotics for the disease are poorly regulated by the government. Dar Yasin/AP hide caption

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The Ebola outbreak "overwhelmed" the World Health Organization and made it clear the agency must change, WHO's director-general, Dr. Margaret Chan, said Monday in Geneva. Fabrice Coffrini /AFP/Getty Images hide caption

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Worth a little pain? Back in 1990, a school boy got a measles shot in the U.K., and it turns out, he got more than protection against the measles. Photofusion/UIG via Getty Images hide caption

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Lucy Barh, head of the Liberian Midwives Association, says of the impending end of the Ebola outbreak: "It is a joy, it is a joy. And I am so grateful to God. The Lord almighty has love for this nation. That is why we have come to this point." Jason Beaubien/NPR hide caption

itoggle caption Jason Beaubien/NPR

Health worker Jackie Carnegie delivers a rubella vaccine in Colorado in 1972. Ira Gay Sealy/Denver Post via Getty Images hide caption

itoggle caption Ira Gay Sealy/Denver Post via Getty Images