1. a Department of Veterinary Microbiology and Parasitology, Faculty of Veterinary Medicine , Makerere University , P.O. Box 7062, Kampala , Uganda
2. b The Open University of Tanzania , P.O. Box 23409, Dar Es Salaam , Tanzania
3. c Department of Veterinary Microbiology and Parasitology, Faculty of Veterinary Medicine , Sokoine University of Agriculture , P.O. Box 3015, Chu Kikuu , Morogoro , Tanzania
4. d Makerere University Graduate School , Makerere University , P.O.Box 7062, Kampala , Uganda
5. e Department of Veterinary Pathobiology , The Royal Veterinary and Agricultural University , 4 Stigbojlen, DK-1870 , Frederiksberg C , Denmark