Abstract
BackgroundVector-borne diseases are among the leading causes of morbidity and mortality in humans and animals. In the Afrotropical region, some are transmitted by Culicoides, such as Akabane, bluetongue, epizootic haemorrhagic fever and African horse sickness viruses. Bluetongue virus infection has an enormous impact on ruminant production, due to its high morbidity and mortality rates.MethodsA nationwide Culicoides trapping campaign was organized at the end of the 2012 rainy season in Senegal. A Maximum Entropy approach (MaxEnt), Boosted Regression Tree (BRT) method and Ecological Niche Factor Analysis (ENFA) were used to develop a predictive spatial model for the distribution of Culicoides, using bio-climatic variables, livestock densities and altitude.ResultsThe altitude, maximum temperature of the warmest month, precipitation of the warmest quarter, mean temperature of the wettest quarter, temperature seasonality, precipitation of the wettest quarter and livestock density were among the most important factors to predict suitable habitats of Culicoides. Culicoides occurrences were, in most of the cases, positively correlated to precipitation variables and livestock densities; and negatively correlated to the altitude and temperature indices. The Niayes area and the Groundnut basin were the most suitable habitats predicted.ConclusionWe present ecological niche models for different Culicoides species, namely C. imicola, C. oxystoma, C. enderleini and C. miombo, potential vectors of bluetongue virus, on a nationwide scale in Senegal. Through our modelling approach, we were able to determine the effect of bioclimatic variables on Culicoides habitats and were able to generate maps for the occurrence of Culicoides species. This information will be helpful in developing risk maps for disease outbreaks.
Highlights
Vector-borne diseases are among the leading causes of morbidity and mortality in humans and animals
For each species we informed the Maximum Entropy approach (MaxEnt) (Fig. 2) and Boosted Regression Tree (BRT) (Fig. 3) models with variables previously found in the Ecological Niche Factor Analysis (ENFA), to predict their geographical distribution
The Niayes area and northern zone were predicted to be favourable for C. imicola (Fig. 2a), C. oxystoma (Fig. 2b), C. enderleini (Fig. 2c)
Summary
Vector-borne diseases are among the leading causes of morbidity and mortality in humans and animals. In the Afrotropical region, some are transmitted by Culicoides, such as Akabane, bluetongue, epizootic haemorrhagic fever and African horse sickness viruses. In the Afrotropical region, Culicoides species are the main vectors for highly devastating viruses such as Akabane, bluetongue (BT), epizootic haemorrhagic fever and African. Studies on the trophic behaviour of Culicoides species have shown that these midges feed on various hosts in Afrotropical region, but mainly on mammals and birds [5,6,7]. The frequency of blood meals is 3 to 5 days depending on the availability of hosts, which are necessary to complete their gonotrophic cycle [8, 9]. Larvae of Culicoides species live in various habitats, but they are mostly wet and enriched in organic matter of animal or plant origin [12,13,14,15,16,17]
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