Environmental risk mapping of canine leishmaniasis in France

Abstract

BackgroundCanine leishmaniasis (CanL) is a zoonotic disease caused by Leishmania infantum, a Trypanosomatid protozoan transmitted by phlebotomine sandflies. Leishmaniasis is endemic in southern France, but the influences of environmental and climatic factors on its maintenance and emergence remain poorly understood. From a retrospective database, including all the studies reporting prevalence or incidence of CanL in France between 1965 and 2007, we performed a spatial analysis in order to i) map the reported cases in France, and ii) produce an environment-based map of the areas at risk for CanL. We performed a Principal Component Analysis (PCA) followed by a Hierarchical Ascendant Classification (HAC) to assess if the locations of CanL could be grouped according to environmental variables related to climate, forest cover, and human and dog densities. For each group, the potential distribution of CanL in France was mapped using a species niche modelling approach (Maxent model).ResultsResults revealed the existence of two spatial groups of CanL cases. The first group is located in the Cévennes region (southern Massif Central), at altitudes of 200-1000 m above sea level, characterized by relatively low winter temperatures (1.9°C average), 1042 mm average annual rainfall and much forest cover. The second group is located on the Mediterranean coastal plain, characterized by higher temperatures, lower rainfall and less forest cover. These two groups may correspond to the environments favoured by the two sandfly vectors in France, Phlebotomus ariasi and Phlebotomus perniciosus respectively. Our niche modelling of these two eco-epidemiological patterns was based on environmental variables and led to the first risk map for CanL in France.ConclusionResults show how an ecological approach can help to improve our understanding of the spatial distribution of CanL in France.

Risk map for cutaneous leishmaniasis in Ethiopia based on environmental factors as revealed by geographical information systems and statistics

“…The data were interpolated into a continuous area based on a 0.81 km 2 grid mesh using the kriging method (Chamaille et al, 2010). The interpolated data was grouped in quintile classes, and the grouped data were used to perform bivariate and multivariate analysis with respect to CL presence/absence for the weighted overlay model.…”

“…In addition to the elevation map, a slope surface (in degrees) was generated from the DEM using kriging interpolation (Chamaille et al, 2010).…”

Detection ofLeishmaniain Red Foxes (Vulpes vulpes) from Southeastern France Using Real-time Quantitative PCR

“…Vectors of Leishmania are usually more abundant below 800 m (Chamaillé et al 2010) and abundance of Phlebotomus perniciosus is related to altitude and stratification of vegetation. The Canjuers camp ecosystem is not generally favorable for development of sandflies.…”

An Accidental But Safe and Effective Use of <I>Lucilia cuprina</I> (Diptera: Calliphoridae) in Maggot Debridement Therapy in Alexandria, Egypt

“…The maximum entropy modelling technique has been used to model plant and insect distributions for purposes such as monitoring invasive species and disease vectors and their potential spread due to climate change (Chamaillé et al 2010;Kulkarni et al 2010;Fischer et al 2011;Gormley et al 2011;Gurgel-Gonçalves et al 2012;Petersen 2013). It performs well on small sample sizes (Pearson et al 2007), which indicates that the generative methods used in MaxEnt give better predictions than the discriminative methods employed by other techniques (Elith et al 2006;Phillip & Dudík 2008).…”