Dengue seroprevalence and seroconversion in urban and rural populations in northeastern Thailand and southern Laos by Doum, D, Overgaard, HJ, Mayxay, M, Suttiprapa, S, Saichua, P, Ekalaksananan, T, Tongchai, P, Rahman, MS, Haque, U, Phommachanh, S, Pongvongsa, T, Rocklöv, J, Paul, R, Pientong, C