[1] Ifakara Hlth Res & Dev Ctr, Dar Es Salaam, Tanzania
[2] Swiss Trop Inst, CH-4002 Basel, Switzerland
[3] Univ London London Sch Hyg & Trop Med, London WC1E 7HT, England
[4] WHO, Dar Es Salaam, Tanzania
[5] Minist Hlth & Social Welf, Dar Es Salaam, Tanzania
[6] Univ Pelotas, Pelotas, Brazil