Bats harbor many types of coronaviruses and were probably the original source of the new coronavirus that appeared in the Middle East. iStockphoto.com hide caption

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Cheryl Gleasner, a research technologist at the Los Alamos National Laboratory, works with a genome sequencing machine designed for disease surveillance. Since the SARS epidemic in 2003, advances in sequencing technologies have greatly speed up the ability to detect and track a new virus. Ross D. Franklin/AP hide caption

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Dr. Vanessa Kerry talks with her father, Sen. John Kerry, before he delivers a speech on health care in Boston. Chitose Suzuki/AP hide caption

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The Durban Children's hospital opened in 1931, as a facility for all races, but tensions during the apartheid era forced it to close in the 1980s. Courtesy of KwaZulu-Natal Children's Hospital hide caption

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Ayo Bello grabs a box of malaria medication at a pharmacy in Lagos, Nigeria. A pilot project by the Global Fund has helped private pharmacies and clinics sell top quality malaria drugs at wholesale prices in Nigeria and seven other African countries. Sunday Alamba/Associated Press hide caption

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A medical worker from the U.S. Centers for Disease Control and Prevention works at the laboratory where Ebola specimens from the Congo were tested at the start of the latest outbreak. Stephen Wandera/AP hide caption

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Doreen Ramogola-Masire, an obstetrician-gynecologist in Botswana, hopes that a simple, quick screen for cervical cancer with vinegar will catch the disease early and save women's lives. Jason Beaubien/NPR hide caption

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A medical worker from the U.S. Centers for Disease Control and Prevention works at the laboratory in Uganda where Ebola specimens were tested at the start of the latest outbreak in the Democratic Republic of Congo. Stephen Wandera/Associated Press hide caption

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A health worker in the Domincan Republic sprays insecticide between houses to stop dengue fever outbreaks this month. Erika Santelices/AFP/Getty Images hide caption

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Nurse Irena Majola tests Justice Mlambo's blood for HIV at a roadside AIDS testing table in a suburb near Cape Town. Under the "test and treat" strategy, about 45 million South Africans would need to be screened for HIV each year. Rodger Bosch/AFP/Getty Images hide caption

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A small, plastic vaginal ring loaded up with an HIV drug protects monkeys from infection with simian immunodeficiency virus. Julie Sitney/Courtesy of the Population Council hide caption

itoggle caption Julie Sitney/Courtesy of the Population Council