Lassa fever is a zoonosis caused by Lassa virus (LASV; family Arenaviridae, genus Lassavirus). The primary reservoir of LASV is the multimammate rat (Mastomys natalensis), which is found throughout sub-Saharan Africa. For a study investigating zoonotic pathogens in rural habitats, we caught small mammals in 3 ecologic zones of Côte d’Ivoire: dry bushland in northern Côte d’Ivoire, around Korhogo; semiarid bushland in central Côte d’Ivoire, around Bouake; and rainforest in southwestern Côte d’Ivoire, near the Taï National Park.