Effect of climate change on vector-borne diseases: Emerging and increasing incidence of zoonotic cutaneous leishmaniasis in Central Tunisia

Abstract

Background Tunisia is one of the most exposed countries to climate change. The increase in temperature and degree of moisture is a favorable condition for the development of vectors of several diseases. Thus, the zoonotic cutaneous leishmaniasis (ZCL), vector-borne disease highly sensitive to climatic conditions, has seen a dramatic resurgence in parts of the country as Sidi Bouzid, taking advantage of the warming in recent decades. The present work aims to assess the vulnerability of the region of Sidi Bouzid to climate change and to analyze the relationship between disease incidence and the bioclimatic variables. Methods This work refers to statistics recorded cases of ZCL in the governorate of Sidi Bouzid and daily observations of the indicators recorded in bioclimatic in the same area (ambient air temperature, rainfall, relative humidity and wind speed) during the period 1963–2016. Generalized additive model was used to investigate the effect of climate on the emergence and the incidence trend of this disease. Results Annual cumulative rainfall showed a slight downward trend in Sidi Bouzid during the period 1963–2016. This trend was more pronounced during the period 1970–2016. The maximum and minimum annual average of temperatures showed a clear tendency to increase over the period 1963–2016. The annual average minimum temperature increased of 5.8 °C between 1963 (10.8 °C) and 2016 (16.6 °C). The increase in the average of daily maximum temperature was estimated at 0.04 C/year. Monthly ZCL incidence was linked to mean temperature and relative humidity both lagged for 4 months ago and cumulative rainfall quantity for the last month. Conclusion Emerging ZCL in Tunisia since the beginning of the 1980 decade is related to the increasing of temperature, to high humidity level and rainfall. Adaptation to climate change should consider this relationship to address ZCL mainly early warning system implementation.