[1] Thammasat Univ, Fac Med, Div Infect Dis, Pathum Thani 12120, Thailand
[2] King Mongkuts Inst Technol, Fac Med, Dept Appl Stat, Ladkrabang, Thailand
[3] Washington Univ, Sch Med, Div Infect Dis, St Louis, MO 63110 USA
[4] Rush Univ, Med Ctr, Div Infect Dis, Chicago, IL 60612 USA