Spatial approach of Echinococcus multilocularis transmission ecology in continental Asia
Résumé
From continental to regional scales, human alveolar echinococcosis spatial distribution is aggregated and forms discrete patches of endemicity within which hotspots of much larger prevalence may occur. Since the late 80s, a number of hotspots have been identified in continental Asia, mostly in China, wherein the ecology of intermediate host communities has been described. This is the case in South Gansu, at the eastern border of the Tibetan plateau, in south Ningxia and in the western Tian Shan of Xinjiang. More recently a new hotspot has been disclosed in the Alay valley of south Kirghizstan, and its ecology is under study. Here we present the natural history of those hotspots comparatively. Based on regional spatial models, we show how interactions between the biodiversity of intermediate host communities, landscape and climate help to explain why transmission is more intense in distinct systems with various intermediate host communities. On this basis, regional types of transmission and their ecological characteristics may be proposed in a general framework and may help to understand the location of other Asian foci that have been reported in literature (e.g. Siberian foci of Russian Altai, Mongolia and Inner Mongolia, north-east China, etc.).