Simultaneous serological assessment of vector and pathogen exposure to support intervention monitoring and understand host–vector interactions

Assessing the presence and magnitude of antibodies to pathogens and vector-saliva, i.e., serosurveillance, is a valuable tool to determine actual exposure of individuals to arthropod vectors and vector-borne pathogens under real life conditions. Antibodies to vector saliva proteins have already demonstrated the potential to serve as biomarkers for exposure to mosquitoes. Since various mosquito species can carry pathogens such as Plasmodia and flaviviruses, positive serological responses to mosquito saliva have been associated with a higher risk of infections in human populations in endemic areas. A recently developed novel high-throughput multiplex assay simultaneously measures antibodies to vector saliva and pathogen-specific antigens as a tool to monitor the efficacy of countermeasures such as repellants and prophylactic drugs in travelers and residents of African malaria-endemic countries. In the current study, this panel was adapted to include vector-specific probes prevalent in Southeast Asia and test samples from serial cross-sectional surveys in Cambodia. The results revealed distinct immune signatures indicative of distinct patterns of host-vector contact, i.e., bite by infected mosquitoes leading to infection or not, or relapse caused by dormant liver-stage parasites. This approach provides a more detailed understanding of exposure dynamics than traditional surveillance methods, while using a single assay. The study establishes the utility of serosurveillance tools for augmenting conventional entomological and serological methods, particularly in low-transmission settings and when rates of infected vectors are low, thus offering a powerful platform for monitoring exposure to vectors and parasites, disease transmission, and evaluating the efficacy of vector control strategies.