Poster by Tran Minh Hang, Nguyen Mai Huong, Pham Duc Phuc, Hung Nguyen-Viet, Dinh Xuan Tung, Tran Thi Tuyet Hanh and Le Thi Phuong Hong presented at the 5th biennial conference of the International Association for Ecology and Health (EcoHealth 2014), Montreal, Canada, 11−15 August 2014.