Predicting current and future distribution of West Nile disease in Tunisia

Abstract

West Nile Disease (WND) is an emerging infectious vector borne disease. Culex pipiens is the most implicated mosquito species in the transmission of WNV in Tunisia. The spatial distribution of this disease has continued to expand in Tunisia since the first epidemic in 1997, while the existing knowledge of environmental factors triggering such events continues to be rather poor. Based on the geographical locations of human WND cases and using ecological factors as predictors, the MaxEnt model was developed to identify environmental factors influencing C. pipiens competence. Potential areas at high risk of WND occurrence under current and future climate background are determined. The key environmental factors affecting vector competence and WND occurrence were the minimum temperature of the coldest quarter and precipitation in the warmest and driest quarter. The risk prediction maps suggested that north-eastern, the eastern and southern coast and oasis areas of Tunisia are potential areas at high risk of WND. Identifying potential environmental factors that influence WND occurrence in Tunisia is the first step for the implementation of a statistically rigorous system for real-time alert and prediction of WND. The potential high risk of WND areas are distributed widely in Tunisia. The epidemiological surveillance system should be enhanced in these high risk regions.