[1] Mahidol Univ, Hosp Trop Dis, Fac Trop Med, Thai Travel Clin, Bangkok 10400, Thailand
[2] Chulabhorn Hosp, Chulabhorn Royal Acad, Bangkok 10210, Thailand
[3] Phramongkutklao Coll Med, Dept Parasitol, Bangkok 10400, Thailand
[4] Mahidol Univ, Fac Trop Med, Dept Clin Trop Med, Bangkok 10400, Thailand
[5] Royal Soc Thailand, Acad Sci, Dusit 10300, Bangkok, Thailand
[6] Univ Ottawa, Fac Med, Dept Med, Ottawa, ON K1N 6N5, Canada