Histamine Ingestion by Anopheles stephensi Alters Important Vector Transmission Behaviors and Infection Success with Diverse Plasmodium Species

An estimated 229 million people worldwide were impacted by malaria in 2019. The vectors of malaria parasites ( spp.) are mosquitoes, making their behavior, infection success, and ultimately transmission of great importance. Individuals with severe malaria can exhibit significantly increased blood concentrations of histamine, an allergic mediator in humans and an important insect neuromodulator, potentially delivered to mosquitoes during blood-feeding. To determine whether ingested histamine could alter biology, we provisioned histamine at normal blood levels and at levels consistent with severe malaria and monitored blood-feeding behavior, flight activity, antennal and retinal responses to host stimuli and lifespan of adult female . To determine the effects of ingested histamine on parasite infection success, we quantified midgut oocysts and salivary gland sporozoites in mosquitoes infected with and . Our data show that provisioning with histamine at levels consistent with severe malaria can enhance mosquito behaviors and parasite infection success in a manner that would be expected to amplify parasite transmission to and from human hosts. Such knowledge could be used to connect clinical interventions by reducing elevated histamine to mitigate human disease pathology with the delivery of novel lures for improved malaria control.