1. School of Public Health, Kunming Medical University, Kunming, Yunnan, China
2. NHC Key Laboratory of Drug Addiction Medicine, Kunming Medical University, Kunming, Yunnan, China
3. Centre for Disease Control and Prevention, Xishuangbanna Dai Autonomous Prefecture, Jinghong, Yunnan, China
4. The Centre for Disease Control and Prevention in Jinghong, Jinghong, Yunnan, China
5. Department of Clinical Skills Centre, Kunming Medical University, Kunming, Yunnan, China