Disease relations: Nyssorhynchus oswaldoi is considered as a potential vector of malaria, whose vector capacity is being studied. It showed low vector capacity, in relation to Nyssorhynchus darlingi, under laboratory conditions (Fonseca and Fonseca, 1942; Rozeboom, 1942). He was found naturally infected in the Brazilian Amazon (Oliveira-Ferreira et al., 1990).

Breeding sites where immature stages develop are found in forested areas, temporary or permanent waters, in general with emerging or floating vegetation (Forattini, 2002). The water is fresh in general and with organic matter although they have been collected in waters with certain salinity (Forattini, 2002). Females are predominantly exophilic and zoophilic but there is evidence of endophilic and anthropophilic in Venezuela and Colombia (Forattini, 2002).