More than 7,000 people have fallen ill with the waterborne disease in a country now cleaning up from flooding brought on by Hurricane Tomas last week.
The storm hit parts of western Haiti on Friday and is blamed for eight deaths.
The cholera outbreak began in northern Haiti about three weeks ago, but health authorities say there have been more cases since the hurricane struck. Contaminated water is a major source of the cholera bacteria.
On Saturday, President René Préval warned the outbreak could grow because of floodwaters.
"The storm has passed," he said. "Now we are bandaging the wounds that the storm has left."
Conditions that help spread cholera have worsened, he said.
"On one side we have the rivers that will carry the bacteria everywhere, and on the other hand, we have the people who have been displaced that could also carry the bacteria."
In Saint Marc, where the first cases appeared, Cuban doctors in charge of a local hospital said medical workers have been seeing more and more cases during the past 24 hours.
