Identification of Parasite-Host Habitats in Anxiang County, Hunan Province, China Based on Multi-Temporal China-Brazil Earth Resources Satellite (CBERS) Images

Zhijie Zhang,Robert Bergquist,Qingwu Jiang,Jie Gao,Dongmei Chen,Zengliang Wang,Baodong Yao

doi:10.1371/journal.pone.0069447

Abstract

Remote sensing is a promising technique for monitoring the distribution and dynamics of various vector-borne diseases. In this study, we used the multi-temporal CBERS images, obtained free of charge, to predict the habitats of the snail Oncomelania hupensis, the sole intermediate host of schistosomiasis japonica, a snail-borne parasitic disease of considerable public health in China. Areas of suitable snail habitats were identified based on the normalized difference vegetation index (NDVI) and the normalized difference water index (NDWI), and the predictive model was tested against sites (snails present or absent) that were surveyed directly for O. hupensis. The model performed well (sensitivity and specificity were 63.64% and 78.09%, respectively), and with further development, we may provide an accurate, inexpensive tool for the broad-scale monitoring and control of schistosomiasis, and other similar vector-borne diseases.

Highlights

Schistosomiasis japonica, a snail-borne parasitic disease of considerable public health and economic significance [1,2,3,4], has existed in China for over 2000 years [5,6,7,8,9]
There are several possible reasons for this: Firstly, habitats of Oncomelania hupensis, the intermediate snail host, are still widely present and this poses a strong risk for the reemergence of schistosomiasis in China [13,14]; Secondly, the compliance rate for repeated drug treatment, the major component of the World Bank Loan Project (WBLP) strategy for schistosomiasis control, has declined substantially [15,16]; Thirdly, reduced financial resources for schistosomiasis control make it hard to maintain the scale of chemotherapy and environmental modification at their previous levels [4,7,17]; the distribution of O.hupensis in China is restricted to the country’s southern parts, where its distribution is strongly governed by the temperature at the macro scale [13,18,19]
We explored the use of 20 m multi-temporal China-Brazil Earth Resources Satellite (CBERS) images to identify potential snail habitats with the simultaneous application of normalized difference water index (NDWI) and normalized difference vegetation index (NDVI) as it would solve the above-mentioned issues

Summary

Introduction

Schistosomiasis japonica, a snail-borne parasitic disease of considerable public health and economic significance [1,2,3,4], has existed in China for over 2000 years [5,6,7,8,9]. The Chinese government initiated a national control program to combat this disease soon after the revolution in 1949, resulting in substantial progress in the following 60+ years [5,6,10]. According to the national schistosomiasis report of 2010, the cases of S. japonica infection and the people at risk were estimated to be about 325,824 and 68,536,200, respectively [11]. Despite this success, there is considerable concern that schistosomiasis might re-emerge as active transmission has been frequently reported in areas that previously reached the criteria of transmission interruption or transmission control [6,12]. It has been suggested that an early warning system (EWS) should be set up in China to monitor the changes of distribution of the intermediate host snail habitats [10]

Methods

Results

Conclusion