Demonstrators waving tree branches and carrying anti-U.N. banners walked from the central plateau city of Mirebalais several miles to the gates of the base perched above a tributary of the Artibonite River — a waterway identified by health officials as a conduit for the infection.

The protesters chanted "Like it or not, they must go" as the Nepalese soldiers and other U.N. peacekeepers remained inside.

Cholera has sparked widespread fear in Haiti, where it was unknown before the outbreak was first noticed by authorities Oct. 20. As of Friday morning, more than 4,700 people have been hospitalized and at least 330 have died, according to the U.N. Office for the Coordination of Humanitarian Affairs.

There has been no scientific conclusion on the origin of the epidemic, which became evident when dozens of patients began dying with high fevers and watery diarrhea at a hospital in the town of St. Marc a few miles from the last stretch of the river.

Experts say the disease was likely imported. Until this month there had not been a diagnosed case of cholera in Haiti as far back as records go in the mid-20th Century, said Claire-Lise Chaignat, head of the global task force on cholera control at the World Health Organization. The disease is pandemic in parts of Africa and Asia.