[1] Mahidol Univ, Fac Trop Med, Bangkok 10400, Thailand
[2] Mahidol Univ, Fac Trop Med, Wellcome Trust Oxford Univ, Mahidol Univ Trop Med Res Program, Bangkok 10400, Thailand
[3] Charles Darwin Univ, Menzies Sch Hlth Res, Darwin, NT, Australia
[4] Flinders Univ S Australia, No Terr Clin Sch, Darwin, NT, Australia
[5] Univ Oxford, Churchill Hosp, Ctr Clin Vaccinol & Trop Med, Nuffield Dept Clin Med, Oxford OX1 2JD, England