Health officials said at least 208 people had died and 2,674 others were infected in an outbreak mostly centered in the Artibonite region north of the capital.

But the number of cases in towns near Port-au-Prince were rising, and officials worried the next target will be hundreds of thousands of Haitians left homeless by January's devastating quake and now living in camps across the capital.

"If the epidemic makes its way to Port-au-Prince, where children and families are living in unsanitary, overcrowded camps, the results could be disastrous," said Dr. Estrella Serrano, World Vision's emergency response health and nutrition manager.

Reports trickled in of patients seeking treatment in clinics closer to Port-au-Prince because the St. Nicholas hospital in the seaside city of St. Marc is overflowing, said Margaret Aguirre, an International Medical Corps spokeswoman.

At least five people who traveled from the Artibonite region to Port-au-Prince on Saturday tested positive for cholera once they arrived in the capital, where they are being treated, she said.

Aguirre said they are not considered the first cholera cases of Port-au-Prince because officials believe the people contracted the disease in Artibonite.

One doctor in the capital reported that a 6-year-old girl from Port-au-Prince's southern Carrefour district tested positive for cholera, although government health officials were investigating and had not confirmed the case.

"The child was in very weak condition," Dr. Willy Lafond Edwight said.

"She couldn't stand up. She couldn't even talk. ... I guarantee that if you find one case, many more cases will appear."

Officials confirmed at least five cholera cases in Arcahaie, a town close to Port-au-Prince, and four cases in Limbe, a small northern municipality.

Ten cases were reported in Gonaives, the largest city in the Artibonite, according to Partners in Health, a U.S.-based humanitarian group.

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

Experts also were investigating possible cases in Croix-des-Bouquet, a suburb of the capital that could act as a transfer point of the disease because it has a widely used bus station, said Paul Namphy with Haiti's national water agency.

"This is a very mobile country," he said. "It can spread like wildfire."
Cholera is a waterborne bacterial infection, and the water agency was nearly doubling the amount of chlorine in drinking water.

Aid groups are providing soap and water purification tablets and educating people in Port-au-Prince about the importance of washing hands.

The groups also began training more staff about cholera and where to direct people with symptoms. Cholera had not been seen in Haiti for decades, and many people don't know about the disease, which causes severe diarrhea and vomiting that can lead to dehydration and death within hours.

Red Cross spokeswoman Julie Sell said teams would begin teaching people in refugee camps how to prevent cholera starting Monday — five days after the outbreak.

"We are taking this very seriously, but we also want to make sure that every one of our people have the information they need," she said.

The International Organization for Migration also was training staff before sending 64 workers out to camps Monday, spokeswoman Sabina Carlson said. But she said the group had begun sending text messages about how cholera spreads and how it can be prevented.

"It's a very new disease in Haiti," she said. "We need to make sure that we've got all the information in order."

Partners in Health also said it would give its health workers additional training Monday before they fan out in Port-au-Prince.

But humanitarian groups can do only so much, said Melody Munz, environmental health coordinator for the International Rescue Committee.

"We can provide soap, and we can provide chlorine. The thing is to get the community to participate," she said.

Mark Schuller, a human rights worker for International Action Ties, said he and others had been meeting with people at camps since Friday and were worried that many had not received information about the outbreak.

"Everyone I'm talking to is saying they haven't heard from a single NGO or government official," he said. "A lot of people don't even know that there's a cholera epidemic."