A suspected outbreak of cholera has killed at least 140 people in central Haiti.
Health officials say more than 1,500 people are known to be infected.
The outbreak, which is centred on two regions north of Port-au-Prince, is Haiti's first cholera epidemic in a century, according to the World Health Organisation.
Officials fear it could spread to the massive and tightly packed camps around the capital, which still house tens of thousands left homeless by January's devastating earthquake.
Experts say up to 80% of cholera cases can be successfully treated with oral rehydration salts.
Safe water and sanitation is critical in reducing the impact of cholera and other waterborne diseases.
The outbreak is being blamed on the Artibonite river, an artery crossing Haiti's rural centre that thousands of people use for much of their daily activities from washing to cooking.
Irish charity Haven, which runs an intensive 'Build it Week' twice a year, has said it has delayed a decision to send 300 volunteers out to the country for at least 48 hours.
The organisation said its self-contained construction site is 40km from the site of the suspected outbreak.