* Outbreak is worst in Sierra Leone's history
* IFRC says more funds needed to stop crisis
* Around 100 cholera deaths in Guinea this year
By Simon Akam
FREETOWN, Aug 23 (Reuters) - Sierra Leone's worst recorded outbreak of cholera risks sparking a wider health crisis unless its causes can be tackled more aggressively, the International Federation of Red Cross and Red Crescent Societies (IFRC) said on Thursday.
The IFRC, which launched an emergency appeal for $1.14 million earlier this month, said the number of cholera cases was continuing to rise and that the number of fatal cases now topped 200.
The water-born bacteria is a regular blight in West Africa where toilet facilities are poor and whose urban slums face flooding every year with the rainy season. Neighbouring Guinea has also seen around 100 deaths so far this year.
Early rains together with increasing overcrowding in cities such as the Sierra Leonian capital Freetown have pushed the number of reported cases close to 12,000 this year, well past the previous record of 10,000 in 1994.
"The disease has the potential to cause a serious humanitarian crisis," Amanda McClelland, IFRC Emergency Health Coordinator, said in a statement. "It is an urgent to step up our efforts as the situation is deteriorating quickly ... We need more funds to deliver the most effective response".
Money spent on tackling the roots of the outbreak so far has been spent on health promotion activities and on helping affected families prepare oral rehydration solutions and build suitable toilets. But the IFRC said the level of aid coverage was still "very low".
It said 217 deaths and 11,992 cases had been reported across 10 districts of the country, half of them among the one- million-strong population of Freetown.
While cholera is generally not fatal, it can kill in just a few hours when diarrhoea and vomiting cause dehydration, especially among the elderly. A cholera outbreak in Haiti that followed its 2010 earthquake killed more than 7,000 people.
The death toll in Sierra Leone is likely to rise further in coming weeks towards the late-September peak of the rainy season. The outbreak is accelerating in Guinea, where around 50 have died of cholera since the start of July.
"We are projecting more cases considering we have a month more of heavy rainfall," said Health Ministry Director of Communications Sidie Yahya Tunis, citing the expansion of the poor suburbs of Freetown as a factor in the disease's spread.
"It's not just that we have more people in the slums, we have more slum areas in the Western Area (around Freetown) as well," he told Reuters. (Writing and additional reporting by Mark John in Dakar and Saliou Samb in Conakry; Editing by Andrew Osborn)