Dirofilaria immitis and Plasmodium relictum DNA detection in populations of Culex quinquefasciatus sampled across Florida

Mosquito-borne diseases comprise a significant part of global health threats, impacting both humans and animals. Among the pathogens vectored by Culex quinquefasciatus mosquitos are Dirofilaria immitis (dog heartworm) and Plasmodium relictum (avian malaria). These diseases significantly impact wildlife, with avian malaria having resulted in the extinction of several endemic bird species in Hawai’i, and dog heartworm costing billions annually in control methods. In Florida, where Cx. quinquefasciatus is common, monitoring these pathogens is critical to controlling the spread of these diseases. This study employed quantitative PCR (qPCR) with a COX1 primer-probe set to detect P. relictum, as well as COX1 D. immitis-specific primers to detect and quantify dog heartworm. Additionally, next-generation sequencing (NGS) was used for its high sensitivity to detect lower quantities of plasmodium in whole mosquito samples. Screening was performed on 1,904 Cx. quinquefasciatus samples sent in from 6 counties across Florida. Finally, P. relictum positives from qPCR were re-screened using cytochrome b primers to determine its lineage.