1. Department of Parasitology, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana.
2. U.S. Naval Medical Research Unit No.3, Ghana Detachment, Accra, Ghana.
3. Division of Infectious Diseases, Department of Internal Medicine, University of Texas Medical Branch, Galveston, Texas, USA.
4. Department of Epidemiology, Noguchi Memorial Institute for Medical Research, University of Ghana, Legon, Ghana.