[Ecology of leishmaniasis in the south of France. 13. Middle slopes of hillsides as sites of maximum risk of transmission of visceral leishmaniasis in the Cévennes (author's transl)].

In the Cévennes, the distribution of canine leishmaniasis and, therefore, of human visceral leishmaniasis is usually on the middle slopes of hillsides. From previous work, it was assumed that the reason is that the same places are the preferred habitats of the sandfly vector, Phlebotomus ariasi Tonnoir, 1921. An investigation was made throughout one season (13.05.1977 to 7.10.1977) of the comparative densities of sandflies at different altitudes on two opposite sides of a selected hill (le massif d'Oiselette) in the department of Gard. Oiled papers, changed every 15 days, were distributed at 22 points at altitudes from 165 to 600 m above sea level. A total of 5,050 sandflies were collected and analysed according to altitude and time of year. Of the sandflies collected, 86,2% were P. ariasi, 0,3% were P. perniciosus Newstead, 1911, 0,1% were P. mascittii Grassi, 1908 and 13,4% were Sergentomyia minuta (Rondani, 1843). P. ariasi was present at all altitudes with maximum densities between 300 and 500 m. This species was present from mid May until late September, with a maximum density at the end of July. The results support the notion that, in the Cévennes, inhabitants of farms and villages on the slopes of hillsides at altitudes of 300-500 m are at the greatest risk of acquiring leishmaniasis because these places are the preferred habitat of the sandfly vector, P. ariasi.