U.N. Secretary General Ban Ki-moon visits a shelter in Les Cayes, Haiti. (Hector Retamal/Agence France-Presse via Getty Images)

MORE THAN six years after a brigade of U.N. peacekeepers from Nepal introduced cholera in Haiti, triggering an epidemic that has killed at least 10,000 and sickened many more, U.N. Secretary General Ban Ki-moon has finally uttered the word “sorry.” Mr. Ban’s tortuously worded apology, delivered recently in a speech to the U.N. General Assembly, must be the beginning, not the end, of official contrition and accountability by the United Nations in Haiti.

The glacial rate at which the United Nations grasped its moral responsibility for having wreaked a public-health disaster in the Western Hemisphere’s most impoverished nation has tarnished the institution. Cowed by its lawyers, jealously guarding its prestige, the United Nations averted its gaze from the victims, ignored incontrovertible scientific evidence and trembled at its potential legal liability.

Only when it became clear that its credibility was in tatters, and its authority to insist that member states adhere to international norms was in jeopardy, did the United Nations finally come to terms publicly with its culpability in the cholera outbreak. “We simply didn’t do enough with regard to the cholera outbreak and its spread in Haiti,” Mr. Ban said. “We are profoundly sorry about our role.”

His statement, coming just a month before his term as the United Nations’ eighth secretary general expires, painstakingly avoided an overt admission of what is already known: that the outbreak began when Nepalese peacekeepers, failing to use basic protocols of sanitation at their base when they arrived in 2010, contaminated a nearby river that provided drinking water for Haitians. Cholera was rampant in Nepal at the time; it had been unknown in Haiti for decades.

What is critical now, as U.N. officials have acknowledged, is that the organization take concrete steps to make amends, namely by leading a public health blitzkrieg to eradicate the disease in Haiti and by making reparations, to victims’ families, their communities or both.

Legal accountability is not the point; a federal appeals panel ruled this summer that the United Nations enjoys diplomatic immunity from the victims’ claims. But moral accountability demands a sustained effort to wipe out a disease that has caused so much suffering in that country.

It won’t be easy. U.N. officials say they have nearly raised the $200 million they sought to overhaul water and sanitation infrastructure in Haiti, and to treat cholera’s steady flow of fresh patients there. That’s a first step toward what is likely to be a long struggle for eradication. Unfortunately, they have made little progress in raising from member states what they hope will be an identical amount of money to provide payouts, scholarships and other benefits to the relatives and communities of the dead.

Under Mr. Ban’s successor, former Portuguese prime minister Antonio Guterres, who takes office Jan. 1, the United Nations has every incentive to press ahead both to heal Haiti to the extent possible and to restore its own moral standing.