Anopheles stephensi is implicated in an outbreak of Plasmodium falciparum parasites that carry markers of drug and diagnostic resistance in Dire Dawa City, Ethiopia, January–July 2022

Abstract Anopheles stephensi, an Asian urban malaria vector, continues to expand across Africa. We investigated the role of An. stephensi in malaria transmission following a dry season outbreak in Dire Dawa, Ethiopia, from April to July 2022, using a prospective case control design. Plasmodium falciparum microscopy-positive febrile patients (n = 101) and microscopy-negative controls (n = 189) were identified and their contacts (n = 662) screened. Spatial clustering of P. falciparum infections detected in the case contacts but not the controls which was strongly associated with detection of An. stephensi and the detection of sporozoites provides the strongest evidence to date for a role of An. stephensi in driving an urban malaria outbreak in Africa. Importantly, this outbreak involved clonal propagation of drug and diagnostic resistant parasites. This study provides the first epidemiological direct evidence linking An. stephensi with increase in malaria transmission in Africa, highlighting the major public health threat of this fast-spreading invasive mosquito.