[1] Univ Cape Town, Div Clin Pharmacol, ZA-7925 Cape Town, South Africa
[2] Hunter New England Populat Hlth, Hlth Protect, Newcastle, NSW, Australia
[3] Univ Cape Town, Dept Stat Sci, ZA-7925 Cape Town, South Africa
[4] MRC, Malaria Lead Res Programme, Durban, South Africa
[5] Mahidol Univ, Fac Trop Med, Bangkok 10700, Thailand
[6] Churchill Hosp, Ctr Vaccinol & Trop Med, Oxford OX3 7LJ, England