Haitian leaders, while dependent on the United Nations to help maintain stability and provide other important services, have also expressed unhappiness over the cholera issue. In an address last Thursday at the annual United Nations General Assembly opening session, Haiti’s prime minister, Laurent Lamothe, spoke of what he called the “moral responsibility” of the United Nations in the outbreak, and said the efforts to combat it had been far from sufficient.

Forensic studies, including one ordered by the United Nations, have identified the culprit bacteria as an Asian strain imported to Haiti by Nepalese members of the United Nations peacekeeping force, known as the United Nations Stabilization Mission in Haiti, which was first authorized in 2004 and maintains about 8,700 soldiers and police officers there, drawn from more than three dozen member states. The forensic studies have also linked the spread of the cholera to a flawed sanitation system at the Nepalese peacekeeper base, which contaminated a tributary that feeds Haiti’s largest river, used by Haitians for drinking and bathing.

Beatrice Lindstrom, a spokeswoman for the Institute for Justice and Democracy in Haiti, the Boston-based rights group that prepared the lawsuit, said in a telephone interview that the listed plaintiffs were five cholera victims, who were seeking redress for themselves and all afflicted Haitians and their families. Ms. Lindstrom said the institute had decided to file the suit in New York because it is the site of United Nations headquarters and has an enormous Haitian expatriate population.

“We are asking for the judge to find the United Nations liable,” she said. “It has violated its legal obligations through reckless actions that brought cholera to Haiti.” The lawsuit did not specify the amount of compensation sought, which Ms. Lindstrom said would be “determined at trial.”

It was far from clear that the lawsuit would be accepted by the court, which affords broad latitude to diplomatic protections for the United Nations against such litigation. These protections are partly rooted in the formal legal conventions created with the inception of the United Nations after World War II. “The majority view is that the U.N. and U.N. entities are immune from domestic lawsuits,” said Jordan J. Paust, a professor of international law at the Law Center of the University of Houston.