The rate of deaths in Haiti's cholera epidemic appears to have slowed as a multinational medical operation ramps up to curb an outbreak that has killed 259 people in the earthquake-hit country.

After several days in which fatalities had numbered dozens each day, only six deaths were recorded in the last 24 hours, all in the main outbreak area of Artibonite in central Haiti, health authorities said.

The accumulated total of confirmed cases rose to 3,342, compared with 3,015 a day ago, reflecting a slowdown.

But Haiti's government and aid partners who have been assisting the poor Caribbean nation since a devastating January 12 earthquake remain on high alert against the possible spread of the deadly diarrheal disease to other parts of the country.

Cholera is transmitted by contaminated water and food. Experts are worried about the vulnerability of 1.3 million quake survivors living in tent and tarpaulin camps. Tens of thousands more live in slums beside filthy watercourses draining into the sea.

Resident continued to fill buckets with water for their daily use from unsecured well sites throughout the tent camps. Many said they were sceptical as to the numbers coming from the daily official reports.

The United Nations, foreign NGOs and foreign governments like Cuba have rushed medical teams, medicines and clean water supplies to the main affected areas, and health authorities have launched a nationwide anti-cholera hygiene campaign.

Special cholera treatment centers have been set up in the main central outbreak areas and the capital, and health officials say sufficient supplies of antibiotic medicines exist in the country to treat up to 100,000 patients.