A cholera outbreak in Freetown, the capital of Sierra Leone, has killed 40 people so far this month, a senior government health official told IRIN on Friday.

He blamed overcrowded slums, torrential rains and infected traders arriving from neighbouring Guinea into Sierra Leone for the country’s first cholera outbreak in five years.

“We have been cholera-free since 1999,” Alhassan Seisay, the director of disease prevention, said by telephone from Freetown. “But since 6 August authorities have recorded 374 cases of the disease and 40 deaths.”

A flow of traders and visitors from Guinea, where the authorities say 32 people have died from cholera this year, had probably played a part in the highly infectious disease returning to Sierra Leone, Seisay said.

“There was a big outbreak in Guinea in June and July and the movement of people from there to Sierra Leone has been one of the underlying causes of our outbreak,” he said.

“Market traders come by boat to Freetown. Also whenever there is a health problem in Guinea, we always get people coming here because they think they can better treatment.”

Cholera causes violent diarrhoea and vomiting, which lead to rapid dehydration of the body. It can prove fatal unless treated quickly.

Seisay said only 20 percent of Sierra Leone’s cholera cases were children. The disease had mainly struck down adults living in the east end of Freetown.

“The reasons are overcrowding in the shanty towns, and a lack of safe and clean drinking water,” he explained.

“The rainy season is making the situation worse. People are depending on streams, rainfall and pools of water that collect because drainage is poor.”

More than 10 people drowned in shanty towns near the river Rokel last month after three days of torrential downpours caused corrugated iron shacks and mud huts to collapse.

Seisay said the Sierra Leonean government had reactivated its Cholera Task Force when the disease first reared its head earlier this month.

Officials are working with medical clinics to treat patients and have sent out an army of 300 community volunteers to educate Freetown residents about collecting water safely and protecting food.

“Day by day we are getting more reports,” Seisay said. “We are worried because even one case of cholera is a problem for Sierra Leone. But we are throwing all the resources we have into stopping the spread.”