Health workers are disinfected with a chlorine solution after treating patients at the Hastings Ebola Treatment Center in Freetown, Sierra Leone. Nine American aid workers have contracted Ebola while working in West Africa. David Gilkey/NPR hide caption

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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

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