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Communication Dans Un Congrès Année : 2011

Landscape, biodiversity and human alveolar echinococcosis distribution: can ecological theory predict disease hotspots in China?

Résumé

To understand infectious disease emergence is one of the current frontiers in environment and health sciences. E. multilocularis sustainability and thus human exposure, in world ecosystems depends on both the existence of suitable host communities supporting the parasite population and meteorological conditions compatible with the survival of free-living eggs. Thus, transmission is an inherently ecological process involving interactions among many species Predictions based on the ecological theory can be made in such complex systems. One is related to the "dilution effect": the diversity of wild animal species may dilute pathogen transmission and thus human exposure to pathogens. In this case transmission intensity would be lower in biodiversity hotspots. Another prediction is that climatic conditions may impact the free-living stages of the parasite (e.g. cold climates and humidity are more favourable to egg survival). A third prediction is that anthropogenic landscapes can impact the population dynamics of species within communities and thus transmission intensity (making e.g. intermediate host population outbreaks and intensive prey-predator interaction more likely). Here we present the results obtained on the scales of continental China and of the eastern border of the Tibetan plateau. Based on data available on human AE distribution, it combines quantified analysis of small mammal biodiversity, land cover and climates. On continental scale, we found that rainfall, altitude and temperature alone do not correlate well to human AE distribution. Small mammal biodiversity, even considering the distribution and the number of small mammal species that are known to be potential pests and intermediate hosts do not correlate to the spatial distribution of human AE. Furthermore, the spatial correlation between the spatial distribution of two of the global land cover 2000 categories, 'meadows' and 'alpine and subalpine meadow', and the spatial distribution of AE is very clear, confirming results obtained in earlier works. On the Tibetan plateau, the analysis was based on a mass screening of 15614 people and 81 villages in a 290,400 km2 area of southern Qinghai and western Sichuan. The Qinghai-Sichuan AE focus lie in one of the area with the lowest regional biodiversity of small mammal in China except if only pest and intermediate host species are considered. A regional model was computed using Bayesian methods. We found there that human AE prevalence was more correlated to landscape and climate variables. An extrapolation of this model on a larger area of 902,800 km2 including Eastern Tibetan Autonomous Region (TAR) and South-Western Gansu predicted correctly the well-know focus of Puma-Zhang county in Gansu, the absence of AE (or the lower of prevalence) observed around the Qinghai lake. It also predicted two possible hotspots in the TAR.

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Dates et versions

hal-00671885 , version 1 (19-02-2012)

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  • HAL Id : hal-00671885 , version 1

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Patrick Giraudoux, Francis Raoul, Tiaoying Li, Xiumin Han, D. R. J. Pleydell, et al.. Landscape, biodiversity and human alveolar echinococcosis distribution: can ecological theory predict disease hotspots in China?. 24th World Congress of Hydatidology, Sep 2011, Urumqi, China. ⟨hal-00671885⟩
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