Jamestown Canyon virus detected in five mosquito taxa in northeastern Illinois

Researchers sampled mosquitoes at eight forest preserves in Cook, DuPage and Lake Counties, Illinois, from May through October 2024. Female mosquitoes from 11 taxa considered potential JCV vectors were pooled by species, collection date and location, then tested using real-time RT-PCR; positive findings were confirmed by sequencing. The study assessed infection prevalence and a vector index based on estimated infection rates and mosquito abundance.

JCV was detected in five taxa: Anopheles punctipennis, Aedes stimulans group, Ae. canadensis, Ae. trivittatus and Coquillettidia perturbans. The highest estimated prevalence was in An. punctipennis. Most detections came from mosquitoes collected in June and early July; the earliest were confined to female Ae. stimulans group mosquitoes.

The findings provide entomologic evidence of JCV transmission in northeastern Illinois and suggest potential for human exposure near suburban forest preserve habitats. The study sampled selected sites and taxa during one season; it did not measure human infections or establish individual risk. The article is an early-release version and may be revised before final publication. The authors call for continued JCV surveillance.