1. Microbiology and Tumor Biology Center, Karolinska Institutet,1 and
2. Research Unit, Albert Schweitzer Hospital, Lambaréné, Gabon2; and
3. Kenya Medical Research Institute, Kisumu Unit, Kisumu, Kenya3
4. Departments of Parasitology4 and
5. Epidemiology,5 Swedish Institute for Infectious Disease Control, Stockholm Sweden; Department of Parasitology, Institute of Tropical Medicine, University of Tübingen, Tübingen, Germany, and