Summary
Understanding mosquito–host associations and feeding behavior is critical for evaluating arbovirus transmission dynamics, identifying amplifier hosts, and mapping zoonotic spillover risk at the urban–forest interface. Following the major 2017–2018 yellow fever outbreak in São Paulo State, Brazil, this study investigated the vertebrate blood meal sources and viral infections of mosquitoes captured across forest fragments in the Serra da Cantareira region (including Alberto Löfgren State Park and Cantareira State Park) between December 2017 and March 2020.
Using a combined pathogen-agnostic Oxford Nanopore sequencing workflow, the researchers identified vertebrate host species from blood-engorged female mosquitoes (targeting mitochondrial COI and Cyt b markers) while simultaneously screening for viral genomes:
Dominant Human Feeding at the Forest Edge: Vertebrate host species were successfully identified in 74.8% of blood-engorged mosquitoes analyzed. Mammals were the predominant hosts, with humans accounting for 76.6% of all identified blood meals.
Anthropophilic Behavior in Sylvatic Vectors: Primary sylvatic yellow fever vectors—including Haemagogus leucocelaenus and Haemagogus capricornii—exhibited pronounced human-biting behavior inside these peri-urban and urban forest parks.
Complete YFV Genome Recovery: Metagenomic sequencing detected yellow fever virus RNA in a blood-engorged Hg. leucocelaenus specimen, recovering a complete YFV genome and confirming active viral circulation among human-biting canopy vectors.
These findings demonstrate that sylvatic yellow fever vectors in urban forest fragments feed frequently on humans, underscoring the persistent risk of mosquito-mediated spillover into densely populated metropolitan areas and the importance of sustained vaccination and entomological surveillance.
