Ecology of leishmaniasis in the South of France. 22. Reliability and representativeness of 12 Phlebotomus ariasi, P. perniciosus and Sergentomyia minuta (Diptera: Psychodidae) sampling stations in Vallespir (eastern French Pyrenees region).

Jean-Antoine Rioux,Montserrat Gállego,Stéphane Carron,José Périères,Michel Babinot,Lamri Zeraia,Evelyne Franquet,Jorian Prudhomme,Jacques Dereure

doi:10.1051/parasite/2013035

Abstract

This study was conducted around Céret (Pyrénées-Orientales, mean elevation 200 m) to test the statistical reliability of 12 stations devoted to sampling the Leishmania infantum vectors Phlebotomus ariasi and P. perniciosus in the South of France. Each station included a retaining wall and the surrounding phytoecological environment (total area: 2,000 m2). The wall had rectangular drainage cavities (weep holes) in which flight interception traps (sticky paper) were inserted and stretched every 10 days from May to October. For both vector species, the statistical analysis of 10-day and annual frequencies led to the following conclusions: (1) P. ariasi densities were significantly higher than P. perniciosus densities, (2) densities per species were significantly different at the 12 stations : none of them could be considered as representative of local vector densities, which depend on the wall structure (exposure, shade, vertebrate hosts), (3) the 10-day variation trends were not significantly different between stations, indicating that these variations are not determined by the station structure but rather by a common external factor (likely meteorological) and (4) the phytoecological features at the stations were not correlated with the sandfly densities. Most of the observations obtained with P. ariasi and P. perniciosus are also relevant for the non-vectorial species S. minuta. In conclusion, future research on the dynamics of leishmaniasis outbreaks relative to climate change and agricultural-silvicultural modifications should be very cautiously carried out, while focusing especially on the vector sampling quality and the use of phytoecological maps as vector density indicators.

Highlights

IntroductionThe epidemiology of leishmaniasis has benefited from ecology-based scientific concepts and methods
For several decades, the epidemiology of leishmaniasis has benefited from ecology-based scientific concepts and methods
These climatic differences could explain the P. ariasi variation patterns, i.e. monophasic in the Cevennes and diphasic at Vallespir. – The significant between-station differences in sampled sandfly abundance were due to the specific environmental conditions at each station [18, 28]

Summary

Introduction

The epidemiology of leishmaniasis has benefited from ecology-based scientific concepts and methods. 4° morphophysiological modifications in parasites during the intravectorial cycle (multiplication, fusion, parietal attachment, metacyclogenesis), 5° Leishmania virulence in vertebrate reservoirs (receptivity, inoculation chancre, visceralization and immunity), 6° the last step of the approach, rational control, involves several techniques (physical, chemical and biological) targeting the cycle overall, i.e. the parasite, vectors and reservoirs. This ecoepidemiological approach was applied in the Mediterranean region, which gave rise to the vector pre-eminence concept, i.e. the sandfly vector is the main factor responsible for the structure and dynamics of leishmaniasis outbreaks [23, 28]. The aim of the present study was to detect potential sampling bias, which could call into question the conclusions of certain previous studies [22]

Objectives

Methods

Results

Conclusion