Between 9 January and 25 April, a total of 164 cases of hepatitis E, including 25 deaths (CFR: 15.2%) have been reported in Diffa region, where there is a population of 673,146. The outbreak was declared by the Nigerien authorities in mid-April. All the deaths occurred among pregnant mothers. Over 76% of reported cases were among females. As of 28 April, five of the six health districts in Diffa region had been affected, with Diffa and N’Guigmi districts accounting for 96% of all cases reported.