Early Detection of Asymptomatic Human Infections in Vector-Borne Diseases: A Programmatic Model for Enhanced Surveillance

Global control strategies for vector-borne diseases (VBDs) remain largely anchored in the detection and management of symptomatic cases, despite substantial evidence that a considerable proportion of infections-often exceeding 60% in several major arboviral diseases-are asymptomatic or minimally symptomatic. These asymptomatic human reservoirs can sustain low-level pathogen circulation during interepidemic periods and may amplify transmission once ecological, immunological, or entomological thresholds are crossed. Because vector-dependent transmission is shaped by environmental variability, vector density, and host immunity dynamics, reliance on symptom-based surveillance alone risks delayed outbreak detection and missed opportunities to prevent severe health outcomes. Evidence from dengue, Zika, West Nile virus, Japanese encephalitis, chikungunya, and Chandipura virus, as well as parasitic diseases such as malaria and visceral leishmaniasis, illustrates how silent human infections complicate surveillance and undermine outbreak anticipation. We propose the establishment of Enhanced Vector-Borne Disease Vigilance Teams (EVBD-VTs) that would serve as mobile, multidisciplinary units integrated with laboratory networks and sentinel systems to strengthen early detection of asymptomatic infections with epidemic potential. Anchored within a One Health framework and supported by laboratory infrastructure, climate-informed risk assessment, and targeted active case detection, this model seeks to shift VBD control from reactive containment to anticipatory preparedness in an era of ecological change.