Without a response the number of people in Chad infected with cholera could double to 25,000 people from the 12,713 cases recorded so far this year, the Red Cross has warned.
"The risk of a wider and more serious outbreak is very real," the International Federation of the Red Cross said in a press statement.
"With the peak of the rainy season coming (in September and October), it is feared that the number of cholera cases will double ... and could reach up to 20,000 to 25,000 cases," the Red Cross explained.
So far this year the disease has killed 364 people, it said, adding that "hundreds more lives" were at risk.
Cholera, an intestinal infection, is transmitted by water soiled by human waste. The disease leads to diarrhoea, dehydration and death if untreated.
The Red Cross said the outbreak was spreading throughout the region, with cases reported in Cameroon, Niger and Nigeria, and expressed concern it could hit refugee camps along the Sudanese border.
The humanitarian agency said it would this week launch an 3 million Swiss franc (2.5 million euro) appeal to assist 200,000 people.
"These funds will be used, among other activities, to train local volunteers, launch awareness campaigns, construct latrines, disinfect water points and to distribute soap and sanitation items," it said.