Linking vector favourable environmental conditions with serological evidence of widespread bluetongue virus exposure in livestock in Ecuador.

Despite existing knowledge of bluetongue disease (BT) in Latin America, little information is available on its actual spread and overall burden. As a vector-borne disease, high-risk areas for BT coincide with environmental conditions favourable for the prevailing vector. In Ecuador, information on the presence of BT is limited to singled out virological findings. In this study, we obtained serological evidence for BT virus exposure from the passive surveillance system of the National Veterinary Service, which monitors reproductive-vesicular diseases, including FMD and BT, as part of differential diagnosis. Bioclimatic factors relevant to Culicoides development as the main vector and host abundance at the parish level were considered as risk factors and analysed using a logistic regression model. The results reveal widespread evidence of bluetongue virus exposure, geographically aligning with favourable vector ecosystems within a temperature range of 12-32 °C. Key variables for predicting high-risk BT areas include cattle population, maximum temperature of the warmest month, minimum temperature of the coldest month, temperature seasonality, and precipitation of the driest month. This analysis, the first of its kind for an Andean country with diverse ecosystems, provides a foundation for initial strategic approaches for targeted surveillance and control measures, considering a One Health approach.