Vector potential index: A trait-based metric bridging competence to contribution

Vector-borne diseases (VBDs) are a growing threat to public health, exacerbated by anthropogenic activities and environmental changes. Understanding and predicting VBD transmission hazard is important for public health prevention and intervention, but becomes increasingly difficult with system complexity. Particularly challenging are zoonotic VBD systems with multiple vectors and hosts, where host use is an important determinant of transmission. Currently, predictions focused on arthropod vectors are often based on known vector competence or vectorial capacity. Neither of these account for host use, omitting a critical element of the natural transmission cycle. Consequently, their applicability may be insufficient, hindering the implementation of effective surveillance and control. Here, we introduce the Vector Potential Index (VPI), a novel metric to quantify a species' relative potential to contribute to transmission cycles based on vector competence and host use together. Using West Nile virus as a model system, we performed a meta-analysis and demonstrate how these traits can be used to calculate ranked enzootic and epizootic VPI values, and highlight how the VPI can help to predict areas with elevated transmission hazard. We argue the inclusion of host use provides a more holistic assessment of species’ actual contribution to transmission in the natural environment. Notably, the VPI framework is adaptable across diverse VBD systems and scales and offers a practical tool for investigations at both species- and community levels. Consequently, this novel approach has considerable potential as a tool for enhancing surveillance and intervention strategies and improving our understanding of complex VBD.