Ecological niche modeling predicting the potential distribution of Leishmania vectors in the Mediterranean basin: impact of climate change

Abstract

BackgroundDue to climate change, the geographical distribution of sand flies during the last decades has shifted northward from latitudes below 45°N in southern Europe to latitudes just above 50○N. Recent studies show that some phlebotomine sand flies were recorded in several parts of Germany and Belgium. In central Europe, some autochthone leishmaniasis cases are being recorded in regions traditionally regarded as leishmaniasis-free. An important challenge is to predict the geographical distribution of leishmaniasis vectors under new climatic conditions. In this study, we attempted to predict the current distribution of six leishmaniasis vectors in the Mediterranean basin and forecast species’ geographical shift under future climate scenarios using an ensemble ecological niche modeling approach. Species records were obtained from scientific surveys published in the research literature between 2006 and 2016. A series of climate metrics describing temperature and precipitation in the study area under two climatic scenarios were obtained from WorldClim database. A consensus model was derived from six varieties of modeling approaches (regression, machine learning and classification techniques) in order to ensure valid prediction of distribution of vectors under different climate scenarios.ResultsModel performance was generally high for the included species with a specificity (true negative rate) ranging from 81.03 to 96.52% (mean = 86.94%) and a sensitivity (true positive rate) ranging from 87.93 to 100% (mean = 96.98%). Our work evidenced the hypothesis of the widespread of Leishmania vectors under climate change scenarios. All of the studied species are prospected to gain new areas that are actually not suitable for vectors’ survival. Phlebotomine sand flies are prospected to invade extra-Mediterranean regions, especially western and central Europe.ConclusionsOur study confirmed the importance of environmental and climate factors on the distribution of leishmaniasis vectors and demonstrated the performance of ecological niche modeling in the prediction of the geographical spread of vector-borne diseases. Ecological niche modeling should be considered in the future as a valuable tool in addition to experimental laboratory studies for a better understanding of the biology of vector species.

Modeling Spatial Distribution of Sergentomyia minuta (Diptera: Psychodidae) and its Potential Implication in Leishmaniasis Transmission in Morocco

“…Ecological niche modelling has been widely used in order to identify the probability of sand fly species occurrence (57). To the best of our knowledge, the present study constitutes a first modeling of Sergentomyia species.…”

“…Precipitation plays an important role in sand flies" life cycle (63). Modeling approach of Chargaff et al (57), found that annual precipitation has a significant role in distribution of Leishmania vector species in Mediterranean basin (57).…”

High-resolution habitat suitability model for Phlebotomus pedifer, the vector of cutaneous leishmaniasis in southwestern Ethiopia

“…The importance of these climate variables could also indicate that the distribution of the vector could alter when the climate changes [36,55,73]. For Ethiopia, it is predicted that the temperature will rise, and rainfall will become erratic with ood and drought events likely to increase [74].…”

“…Because temperature and precipitation are relevant drivers for the distribution of P. pedifer, bioclimatic variables were derived from 'Climatologies at high resolution for the earth's land surface areas' (CHELSA, https://chelsa-climate.org/bioclim/) with a spatial resolution of 30 arcsec (~ 1 km) [16,31]. A subset of seven out of 19 available bioclimatic variables were considered ecologically relevant to the species and selected, in particular annual averages and extrema (minimum and maximum) for both temperature and precipitation and a variable describing the annual rainfall variation as a measure for seasonality [36].…”

Broader Geographical Distribution of Toscana Virus in the Mediterranean Region Suggests the Existence of Larger Varieties of Sand Fly Vectors

“…Climate change affects the geographical distribution of many sand fly species [65,66]. As a consequence, the geographical distribution of sand flies has expanded towards Northern Europe during the last decade.…”