Flooding across Nigeria has killed at least 137 people and displaced more than 35,000 since July, the Red Cross said Monday, warning that latest forecasts suggest the damage could still worsen. Heavy rainfall in two northern states has spilled contaminants into drinking wells, leading to a cholera outbreak that has killed at least eight and left scores of others hospitalized, according to local officials. Various agencies have offered different figures for the lives lost during the rainy season and the Red Cross did not include the cholera deaths among its flood toll. The states affected by floods range from Lagos in the southwest to Adamawa in the northeast, where at least 30 people died following the release of water from a dam in Cameroon that caused Nigeria\'s River Benue to overflow. The disaster management coordinator with the Nigeria Red Cross, Umar Mairiga, who provided the death toll, said 36,331 people had been displaced across 15 affected states. \"The latest information that may compound the situation is that the River Niger is overflowing its banks,\" he told AFP, referring to the river that cuts through several southern and central states. Riverbank communities in central states like Kogi \"may be submerged\", Mairiga said. Emergency officials in Adamawa have reported 65 confirmed cases of cholera. In the northern state of Katsina, west of Adamawa, the chairman of the Faskari local government area, Isyaku Faskari-Ahmed, said two villages have \"lost eight people to cholera (and) more than 70 were hospitalized from the disease.\" Heavy rainfall has propelled a cholera outbreak in several west African countries. In Sierra Leone, the hardest hit, at least 244 people have died and more than 14,000 thousand have been affected. Cholera, an intestinal infection, is transmitted by water soiled by human waste. The disease leads to diarrhea, dehydration and death if untreated. More than 200 deaths from the water-borne infection were recorded during Nigeria\'s seasonal downpour last year. The rainy season in Nigeria, Africa\'s most populous country with about 160 million people, runs roughly from March to September.