1. Faculty of Veterinary Science; University of Zimbabwe; PO Box MP167, Mount Pleasant Harare Zimbabwe
2. Faculty of Medicine; University of Zimbabwe; PO Box MP167, Mount Pleasant Harare Zimbabwe
3. Department of Cell Biology and Histology; Faculty of Veterinary Medicine; Utrecht University; PO Box 80.158 3508 TD Utrecht The Netherlands
4. AmCOGG Research Institute Amsterdam Centre for Health and Health Care Research; Meibergdreef 9 1105 AZ Amsterdam The Netherlands
5. Department of Pathobiology; Faculty of Veterinary Medicine; Utrecht University; PO Box 80.158 3508 TD Utrecht The Netherlands