1. Lao Tropical and Public Health Institute, Ministry of Health, Vientiane Capital, Lao PDR
2. Swiss Tropical and Public Health Institute, Allschwil, Switzerland
3. University of Basel, Basel, Switzerland
4. Department of Radiology, Mahosot Hospital, Ministry of Health, Vientiane Capital, Lao PDR
5. Immunization Unit, Robert Koch Institute, Berlin, Germany