Spatial distribution and habitat selection of culicoides imicola: The potential vector of bluetongue virus in Tunisia.

Ben H Thameur,Salah Hammami,Heni Haj Ammar,Sghaier Soufiène

doi:10.4102/ojvr.v88i1.1861

Abstract

The increasing threat of vector-borne diseases (VBDs) represents a great challenge to those who manage public and animal health. Determining the spatial distribution of arthropod vector species is an essential step in studying the risk of transmission of a vector-borne pathogen (VBP) and in estimating risk levels of VBD. Risk maps allow better targeting surveillance and help in designing control measures. We aimed to study the geographical distribution of Culicoides imicola, the main competent vector of Bluetongue virus (BTV) in sheep in Tunisia. Fifty-three records covering the whole distribution range of C.imicola in Tunisia were obtained during a 2-year field entomological survey (August 2017 – January 2018 and August 2018 – January 2019). The ecological niche of C. imicola is described using ecological-niche factor analysis (ENFA) and Mahalanobis distances factor analysis (MADIFA). An environmental suitability map (ESM) was developed by MaxEnt software to map the optimal habitat under the current climate background. The MaxEnt model was highly accurate with a statistically significant area under curve (AUC) value of 0.941. The location of the potential distribution of C. imicola is predicted in specified regions of Tunisia. Our findings can be applied in various ways such as surveillance and control program of BTV in Tunisia.

Highlights

The spread of disease vectors and the growing number of vector-borne diseases (VBDs) pose a major threat to human and animal health
The ecological-niche factor analysis (ENFA) method provides for our presence data an overall marginality of m = 7.706, showing that C. imicola habitat is very different from the mean habitat of the study area (C. imicola presence needs specific ecological conditions) and an overall specialisation of s = 2.663, which means that we found C. imicola in a small range of conditions
We present here the potential ecological niche for C. imicola in Tunisia

Summary

Introduction

The spread of disease vectors and the growing number of vector-borne diseases (VBDs) pose a major threat to human and animal health. Despite considerable success in controlling communicable diseases, VBDs have caused and still cause damage on different continents. Bluetongue virus (BTV) infects domestic and wild ruminants and it is transmitted by biting midges of the genus Culicoides (Diptera: Ceratopogonidae). Between 1999 and 2002, BTV serotype 2 epizootics have occurred in Tunisia (Ben Fredj et al 2003; Hammami 2004). In 2006 and 2009, Tunisia’s General Directorate of Veterinary Services (DGSV) warned of incursion of two additional serotypes: BTV1 and BTV4, successively (Lorusso et al 2013; Sghaier et al 2014). Culicoides imicola is the main potential vector of BT in Tunisia (Hammami 2004; Sghaier et al 2014)

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