A cholera outbreak has killed more than 6,000 people in Haiti since October and is far from under control. More than 420,000 people have been sickened since the disease emerged in a rural area north of Port-au-Prince, apparently after sewage from an encampment of United Nations peacekeepers contaminated the Artibonite River.

Cholera is preventable and easily treated, but containment has been stymied by the chronic deficiency — or utter absence — of clean water and sanitation systems in Haiti, particularly in the countryside, where cholera hit first and hardest. The cholera mortality rate in Haiti’s vulnerable Southeast region was 5.3 percent in July. Access to proper treatment could keep that rate below 1 percent.

The United Nations’s Pan-American Health Organization, the United States and the rest of the international community should be working with the Haitian Health Ministry to wage a more aggressive and effective effort, which should include not only clean water and sanitation systems but more antibiotics and cholera vaccinations. A cheap, effective cholera vaccine is available, but there are currently fewer than 400,000 doses worldwide. Ramping up manufacturing to make more vaccine could be readily done and would have global benefits.

Cholera victims are among the many casualties of the unfinished rebuilding of Haiti, still choked by rubble and political paralysis. Haiti’s new president, Michel Martelly, a political novice, has been unable to form a government. Donations have lagged, construction plans are stuck on drawing boards and hundreds of thousands are in displaced-persons camps, hot spots of disease and suffering.