1. KEMRI Centre for Geographic Medicine Research, Coast, P.O. Box 230-80108, Kilifi, Kenya
2. London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, United Kingdom
3. BPRC, Department of Parasitology, P.O. Box 3306, 2280 GH Rijswijk, Netherlands
4. Medical Research Council Laboratories, Fajara, P.O. Box 273, Banjul, the Gambia