Effects of Trypanosoma brucei infection and treatment on haematoserological response of West African Dwarf sheep to Brucella abortus vaccine

Abstract

This study aims to investigate the effects of Trypanosoma brucei infection and treatment on haematoserological status of West African Dwarf sheep to Brucella abortus vaccine. Twenty-four adult WAD sheep of mixed sexes were randomly assigned into 6 groups of 4 each. They were either infected with 1 × 106 trypanosomes intravenously (groups 2–6) or uninfected (group 1). The different groups were treated as follows: group 2 (positive control—7 mg/kg diminazene aceturate (DA)), group 3 (7 mg/kg DA and 5 mg/kg levamisole), group 4 (7 mg/kg DA and 50, 000 IU vitamin A), group 5 (7 mg/kg DA and 50, 000 IU vitamin A 3 weeks post infection), and group 6 (7 mg/kg DA and 5 mg/kg levamisole and 50, 000 IU vitamin A). All the animals were vaccinated with B. abortus S19 vaccine 2 weeks post infection (PI). Parameters assessed parasitaemia, total and differential white blood cell counts, and antibody titres to B. abortus antigen. Average prepatent period was 5 days. Trypanosomes were completely cleared from the bloodstream following treatment. There was no relapse parasitaemia recorded. By weeks one and two post infection, there was significant (P < 0.05) leucocytosis which was due to lymphocytosis and neutrophilia in all infected groups. There were no significant changes in monocytes, oesinophils, basophils, and antibody titres of both infected and uninfected sheep. Experimental T. brucei infection and treatment of WAD sheep caused significant (P < 0.05) leucocytosis 1 to 2 weeks PI due to lymphocytosis and neutrophilia, but no significant differences in antibody titres to B. abortus S19 vaccine when compared with the vaccinated uninfected.