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

itoggle caption Ramon Espinosa/AP

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

Village chiefs, residents and government officials take to the streets to celebrate the Chienge district's accomplishment of bringing sanitation to every home. Mark Maseko/Courtesy of UNICEF Zambia hide caption

itoggle caption Mark Maseko/Courtesy of UNICEF Zambia

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

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