Haitians protest against the United Nations peacekeepers in Port-au-Prince in November 2010. Hector Retamal/AFP/Getty Images hide caption

itoggle caption Hector Retamal/AFP/Getty Images

Thousands of doses of cholera vaccine sit in a refrigerated trailer in a United Nations compound in Saint-Marc, Haiti, in March. After some delays, a vaccination project proved successful. John Poole/NPR hide caption

itoggle caption John Poole/NPR