1. Department of Biology, Imperial College of Science Technology and Medicine
2. Medical Microbiology, Imperial College School of Medicine, St Mary's Campus, London, UK
3. Antenne Orstom aupres du Centre Pasteur BP 1274, Yaounde, Cameroun
4. Institute of Zoology, Zoological Society of London, London, UK
5. National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD, USA
6. Department of Biological Sciences, Salford University, Salford, UK