Modeling the effectiveness of Esperanza Window Traps as a complementary vector control strategy for achieving the community-wide elimination of Onchocerciasis

Shakir Bilal¹Morgan E Smith²Swarnali Sharma³Wajdi Zaatour¹Ken Newcomb¹Thomas Unnasch¹Edwin Michael^1*

• ¹University of South Florida, Tampa, United States
• ²University of Notre Dame, Notre Dame, United States
• ³Vijaygarh Jyotish Ray College, Kolkata, India

Abstract Mathematical models of parasite transmission provide powerful quantitative tools for evaluating the impact of interventions for bringing about the control or elimination of community-level disease transmission. A key attribute of such tools is that they allow integration of field observations regarding the effectiveness of an intervention with the processes of parasite transmission in communities to allow the exploration of parameters connected with the optimal deployment of the intervention to meet various community-wide control or elimination goals. In this work, we analyze the effectiveness of the Esperanza Window Trap (EWT), a recently developed black fly control tool, for eliminating the transmission of Onchocerca volvulus in endemic settings by coupling seasonally-driven onchocerciasis transmission models identified for representative villages in Uganda with a landscape-level, spatially-informed model of EWT trap configurations for reducing Simuliid fly populations in a given endemic setting. Our results indicate that when EWT traps are used in conjunction with MDA programs there are significant savings in the number of years needed to reach a specified set of elimination targets compared to the use of MDA alone. Adding EWT after the meeting of these thresholds and stoppage of MDA also significantly enhances the long-term sustained elimination of onchocerciasis. The number of traps required is driven by the trap’s black fly killing efficiency, capture range, desired coverage, inter-trap distance, size of location, and the spatial heterogeneity of the fly population in a given village/site. These findings provide important new knowledge regarding the feasibility and effectiveness of the community-wide use of EWT as a supplementary intervention alongside MDA for accelerating and sustaining the achievement of sustainable onchocerciasis elimination. Our coupling of landscape models of EWT deployment with the seasonal onchocerciasis transmission model also highlights how population-level macroparasite models may be extended effectively for modeling the effects of spatio-temporal processes on control efforts.