ST. MARC, Haiti — An outbreak of cholera has spread outside a rural valley in central Haiti, intensifying worries the disease could reach squalid tarp camps that house hundreds of thousands of earthquake survivors in the capital.

By Saturday more than 200 were confirmed dead in the poor Caribbean nation’s worst health crisis since the Jan. 12 quake, and authorities said more than 2,000 were sick.

The cholera outbreak has been centered in the central Artibonite region, but at least five cases were confirmed in Arcahaie, a town closer to the quake-devastated capital, Port-au-Prince. Another four cases were reported in Limbe, a small northern municipality.

Experts also were investigating possible cases in Croix-des-Bouquet, a suburb of the capital. Another 10 cases were reported in Gonaives, the largest city in the Artibonite, according to Partners in Health, a U.S.-based humanitarian group.

The sick include 50 inmates at a prison in Mirebalais, just north of Port-au-Prince, Health Ministry director Gabriel Thimothe said.

Health officials are fearful about the outbreak spreading into the capital, where thousands and thousands of people are living in unsanitary conditions in refugee camps.

“It will be very, very dangerous,” said Claude Surena, president of the Haitian Medical Association. “Port-au-Prince already has more than 2.4 million people, and the way they are living is dangerous enough already.” clearly a lot more needs to be done.”

Aid groups and the government were rushing in medical and relief supplies, including 10,000 boxes of water purification, according to the World Health Organization.

The Ministry of Health has confirmed 208 deaths and a total of 2,394 cases of cholera, said Imogen Wall, a spokeswoman for the U.N. Office for the Coordination of Humanitarian Affairs.

“It’s concentrated in Artibonite right now and we’re doing our best to keep it that way,” Wall said.

Dozens of patients lay on the floor awaiting treatment at the St. Nicholas hospital in the seaside city of St. Marc on Friday, some of them brushing away flies on mattresses stained with human feces.

One, 55-year-old Jille Sanatus, was brought in by his son Jordany the night before. A doctor was struggling to stick a needle into his arm.

“He’s completely dehydrated, so it’s difficult. It’s hard to find the vein,” said Dr. Roasana Casimir, who had been working nearly without rest since the outbreak became apparent Wednesday.

Casimir finally penetrated the vein and fluid from an IV bag began to trickle in, but half an hour later the father of 10 was dead. Two hospital employees carried the body to the morgue behind the hospital and placed it on the ground for the family to reclaim for a funeral.

Sanatus’ son said the family had been drinking water from a river running down from the central plateau region. Health Minister Alex Larsen said Friday that the river tested positive for cholera.

Wall said the sick patients and the contagious remains of the dead were insufficiently quarantined.

“Part of the problem has been people are moving around a lot, and there hasn’t been proper isolation in place at the clinics,” she said.

The sick come from across the desolate Artibonite Valley, a region that received thousands of refugees following the Jan. 12 earthquake that killed as many as 300,000 people and destroyed the capital 45 miles (70 kilometers) south of St. Marc. Most of the new arrivals have been taken in by host families.

Cholera was not present in Haiti before the earthquake, but experts had warned that conditions were ripe for disease to strike in areas with limited access to clean water.

“You cannot say it is because of the earthquake, but because of the earthquake the situation here requires a high level of attention in case the epidemic extends,” said Michel Thieren, a program officer for the Pan-American Health Organization.

Cholera is a bacterial infection spread through contaminated water. It causes severe diarrhea and vomiting that can lead to dehydration and death within hours.

Larsen, the health minister, urged anyone suffering diarrhea to make their own rehydration serum out of salt, sugar and water to drink on the way to a hospital.

The number of cases will continue to grow because Haitians do not have any built-up immunity to cholera, said Jon Andrus, deputy director of the Pan American Health Organization’s Regional Office for the Americas, which is sending medical teams to the neighboring Dominican Republic as a preventive measure.

“We have all the things in place for something we know will get bigger,” Andrus said.

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Associated Press writers Mike Melia and Danica Coto in San Juan, Puerto Rico, contributed to this report.