Presence and Abundance of Malaria Vector Species in Miami-Dade County, Florida

Abstract Malaria outbreaks have sporadically occurred in the United States, with Anopheles quadrimaculatus serving as the primary vector in the eastern region. Anopheles crucians, while considered a competent vector, have not been directly implicated in human transmission. Considering the locally acquired Plasmodium vivax cases in Sarasota County, Florida (7 confirmed cases) and Cameron County, Texas (one confirmed case) in the summer of 2023, we hypothesized that other major urban areas in the United States harbor conducive conditions for local malaria transmission. Thus, our objective is to profile the most abundant Anopheles vector species in Miami-Dade, Florida – An. crucians and An. quadrimaculatus. We analyzed high-resolution mosquito surveillance data from 2020 to 2022 in Miami-Dade County, Florida. A total of 36,589 An. crucians and 9,943 An. quadrimaculatus were collected during this study by the surveillance system (which comprises 322 CO2-based traps). Our findings reveal a highly heterogeneous distribution of An. crucians and An. quadrimaculatus in Miami-Dade County, highlighting the presence of highly conducive environments in transition zones between natural/rural and urban areas. Anopheles quadrimaculatus, and to a lesser extent An. crucians, pose a considerable risk of malaria transmission during an outbreak, given their high abundance and close proximity to humans. Understanding the factors driving Anopheles vector species' proliferation, population dynamics, and spatial distribution is vital for implementing effective mosquito control and reducing the risk of malaria outbreaks in the United States.