An outbreak of suspected cholera has killed at least 135 people in central Haiti and sickened hundreds more who overwhelmed a crowded hospital seeking treatment.
Hundreds of patients lay on blankets in a car park outside St Nicholas hospital in the port city of St Marc with drips in their arms for rehydration.
Doctors were testing for cholera, typhoid and other illnesses in the Caribbean nation's deadliest outbreak since the earthquake in January that killed as many as 300,000 people.
Catherine Huck, deputy country director for the UN Office for the Coordination of Humanitarian Affairs (OCHA), said the Caribbean nation's health ministry had recorded 135 deaths and more than 1,000 infected people.
"What we know is that people have diarrhoea, and they are vomiting, and (they) can go quickly if they are not seen in time," Huck said. She said doctors were still awaiting lab results to pinpoint the disease.
The president of the Haitian Medical Association, Claude Surena, said the cause appeared to be cholera, but added that had not been confirmed by the government.
"The concern is that it could go from one place to another place, and it could affect more people or move from one region to another one," he said.
Cholera is a bacterial infection spread through contaminated water. It causes severe diarrhoea and vomiting that can lead to dehydration and death within hours. Treatment involves administering a salt and sugar-based rehydration serum.
The sick come from across the rural Artibonite region, which did not experience significant damage in the earthquake but has absorbed thousands of refugees from the devastated capital 45 miles south of St Marc.
The US Embassy in Port-au-Prince issued an advisory urging people to drink only bottled or boiled water and eat only food that has been thoroughly cooked.