Affiliation: Department of Pathology and Microbiology, School of Medicine, University of Zambia, P. O. Box 32379, Lusaka, Zambia; Department of Clinical Studies, School of Veterinary Medicine, University of Zambia, P. O. Box 32379, Lusaka, Zambia; Africa Centre of Excellence for Infectious Diseases of Humans and Animals, University of Zambia, Lusaka, Zambia.