The death toll from the cholera epidemic in Haiti has exceeded 500 the government says.
Doctors in Saint Marc, where the cholera outbreak began three weeks ago, say they are beginning to see patients with cholera and typhoid fever at the same time.
Hurricane Tomas caused flooding and left eight people dead in western Haiti.
Haitian president Rene Preval says there is a serious risk the disease will spread.
He says there is a risk from the rivers that carry the bacteria, and people who have been displaced could also carry it.
Cholera causes diarrhoea and vomiting, leading to severe dehydration, but can kill quickly. It is treated easily through rehydration and antibiotics.