Evidence for a role of Anopheles stephensi in the spread of drug- and diagnosis-resistant malaria in Africa

Anopheles stephensi, an Asian malaria vector, continues to expand across
Africa. The vector is now firmly established in urban settings in the Horn
of Africa. Its presence in areas where malaria resurged suggested a
possible role in causing malaria outbreaks. Here, using a prospective
case–control design, we investigated the role of An. stephensi in
transmission following a malaria outbreak in Dire Dawa, Ethiopia in
April–July 2022. Screening contacts of patients with malaria and febrile
controls revealed spatial clustering of Plasmodium falciparum infections
around patients with malaria in strong association with the presence of
An. stephensi in the household vicinity. Plasmodium sporozoites were
detected in these mosquitoes. This outbreak involved clonal propagation of
parasites with molecular signatures of artemisinin and diagnostic
resistance. To our knowledge, this study provides the strongest evidence
so far for a role of An. stephensi in driving an urban malaria outbreak in
Africa, highlighting the major public health threat posed by this
fast-spreading mosquito.