Transmission ecosystems ofEchinococcus multilocularisin China and Central Asia

Abstract

SUMMARYFrom continental to regional scales, the zoonosis alveolar echinococcosis (AE) (caused by Echinococcus multilocularis) forms discrete patches of endemicity within which transmission 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, in the western Tian Shan of Xinjiang, and in the Alay valley of south Kyrgyzstan. Here we present a comparative natural history and characteristics of transmission ecosystems or ecoscapes. On this basis, regional types of transmission and their ecological characteristics have been proposed in a general framework. Combining climatic, land cover and intermediate host species distribution data, we identified and mapped 4 spatially distinct types of transmission ecosystems typified by the presence of one of the following small mammal ‘flagship’ species: Ellobius tancrei, Ochotona curzoniae, Lasiopodomys brandtii or Eospalax fontanierii. Each transmission ecosystem had its own characteristics which can serve as a reference for further in-depth research in the transmission ecology of E. multilocularis. This approach may be used at fine spatial scales to characterize other poorly known transmission systems of the large Eurasian endemic zone, and help in consideration of surveillance systems and interventions.

Global Distribution of Alveolar and Cystic Echinococcosis

“…Transmission in the TAR and in other Tibetan regions includes a wildlife cycle with Tibetan foxes (V. ferrilata) and microtine and/or ochotonid small mammal species . Furthermore, the role of domestic dogs in AE transmission in TAR is probably similar to that described in Tibetan communities in northwest Sichuan (Giraudoux et al, 2013a;Vaniscotte et al, 2011). p0505…”

Trophic ecology, behaviour and host population dynamics in Echinococcus multilocularis transmission

“…On the Tibetan plateau, Wang et al (2007) showed that E. multilocularis prevalence in domestic dogs was positively associated with the relative density of small mammals living in common grasslands, a habitat where Ochotona sp. and C. kamensis population regularly reach high levels (Raoul et al, 2006;Giraudoux et al, 2013). Moreover, the E. multilocularis worm burden in dogs (mean = 39.64 worms) was positively correlated with the relative abundance of Ochotona sp.…”

Echinococcosis

“…Environmental factors such as altitude, climate (low temperatures or high annual precipitations), landscape characteristics and use, and predator-prey relationship (availability and predation level on potential intermediate hosts) play a critical role in E. multilocularis infection in foxes Giraudoux et al 2013). AE forms discrete patches of endemicity within which transmission hot spots of much higher prevalence occur.…”