[1] Shanxi Univ, Complex Syst Res Ctr, Taiyuan 030006, Shanxi, Peoples R China
[2] North Univ China, Dept Math, Taiyuan 030051, Shanxi, Peoples R China
[3] Fudan Univ, Sch Math Sci, Shanghai 200433, Peoples R China
[4] China Anim Hlth & Epidemiol Ctr, Qingdao 266032, Shandong, Peoples R China
[5] Jilin Anim Dis Prevent & Control Ctr, Changchun 130062, Jilin, Peoples R China