1. Department of Medical Microbiology and Immunology, Centre for Medical Parasitology, Department of Infectious Diseases,
2. Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
3. National Institute for Medical Research, Amani, Tanga, Tanzania
4. Department of Medical Microbiology, University Medical Center, 6525 GA Nijmegen, Netherlands
5. Department of Medical Biochemistry and Genetics, University of Copenhagen, Copenhagen University Hospital, 2200 Copenhagen, Denmark