1. Thai Travel Clinic, Hospital for Tropical Diseases, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
2. Department of Clinical Tropical Medicine, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
3. Department of Tropical Hygiene, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
4. Department of Community Medicine, Faculty of Medicine, Chiang Mai University, Chiang Mai 50200, Thailand
5. Department of Helminthology, Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
6. School of Medicine, Mae Fah Luang University, Chiang Rai 57100, Thailand
7. School of Medicine, University of Galway, H91 TK33 Galway, Ireland
8. School of Medicine, International Medical University, Kuala Lumpur 57000, Malaysia