Haiti braced for a new battering on Thursday as Tropical Storm Isaac swept across the Caribbean toward the shattered island, gathering strength and threatening to reach hurricane force.
About 400,000 residents were dangerously exposed to Isaac's gathering fury in makeshift squatter camps, two years after an earthquake destroyed the Haitian capital Port-au-Prince.
"They remain amongst the most vulnerable, should the storm hit the city," said Jean-Claude Mukadi, Haiti national director for humanitarian group World Vision.
"Without a stable sanitation system or permanent housing, heavy rain and wind can create much larger problems like disease from water contamination."
Isaac is forecast to hit Hispaniola island, which contains Haiti and Dominican Republic, at approximately 12 GMT on Friday, and is expected to deliver between 300 and 500 mm of rain.
Haiti has always struggled to cope with the aftermath of natural disasters. Deforestation has made Haiti highly vulnerable to landslides and flash flooding, and since the earthquake of 2010, the situation is even more serious.
Immediately after the quake, it’s estimated that 1.5 million people were housed in impromptu settlements.
If this storm follows the forecast, then it will cause widespread flooding and potentially landslides as well. This will be hazardous to anyone in the country, and tarpaulins will provide little, if any, protection.
Preparations are under way in the Caribbean, where the Tropical Storm is expected to gather strength and be upgraded to a hurricane.
Residents in the neighbouring Dominican Republic and on nearby Puerto Rico rushed to erect defences against the expected wind and rain, set to sweep on to Cuba and the southern US by the weekend.
"Isaac could become a hurricane as it nears Haiti on Friday... Preparations to protect life and property should be rushed to completion," the Miami-based US National Hurricane Center said.
At 00:00 GMT, Isaac was "a little stronger," with maximum sustained winds of 75km per hour as it headed west-northwest at 26km per hour, according to the NHC.