1. Thitima Wongsaroj, Bureau of General Communicable Diseases, Department of Disease Control, Ministry of Public Health, Nonthaburi 11000, Thailand
2. Faculty of Medicine, Mahasarakham University, Mahasarakham 44150, Thailand
3. Faculty of Tropical Medicine, Mahidol University, Bangkok 10400, Thailand
4. Bureau of General Communicable Diseases, Department of Disease Control, Ministry of Public Health, Nonthaburi 11000, Thailand
5. Department of English, Faculty of Liberal Arts, Huachiew Chalermprakiet University, Samut Prakarn 10540, Thailand