The U.N. children’s agency says almost 2,500 people have died in one of the biggest cholera outbreaks western Africa has ever seen.

UNICEF says more than 85,000 cases have been reported in 10 countries from Mali to Congo this year.

The U.N. body says “the region is facing one of the biggest epidemics in its history” with case fatality rates as high as 4.7 percent.

A case fatality rate of more than 1 percent is usually considered too high.

UNICEF spokeswoman Marixie Mercado said Tuesday that above-average rainfall predicted for the coming weeks increases the likelihood that cholera will continue to spread.