[1] Chulalongkorn Univ, King Chulalongkorn Mem Hosp, Fac Med,World Hlth Organ Collaborating Ctr Res &, Thai Red Cross Emerging Infect Dis Hlth Sci Ctr, Bangkok 10330, Thailand
[2] Chulalongkorn Univ, Dept Med, Div Neurol, Bangkok, Thailand
[3] Chulalongkorn Univ, King Chulalongkorn Mem Hosp, Fac Med,Div Infect Dis,Dept Med, Thai Red Cross Emerging Infect Dis Clin Ctr, Bangkok 10330, Thailand