Assessment of the influence of levees along Yangtze River on Oncomelania hupensis, the intermediate host of Schistosoma japonicum oleh Shen Chen, Yin-Long Li, Lei Duan, Jian-Bing Liu, Jie Zhou, Dan-Dan Lin, Shi-Qing Zhang, Kun Yang, Li-Yong Wen, Yan-Jun Jin, Shang Xia, Jing Xu, Shan Lv, Shi-Zhu Li, Xiao-Nong Zhou