Primary and Secondary Humoural Immune Response to Anti-Rabies Vaccination in Dogs Experimentally Infected with Single Trypanosoma brucei and Trypanosoma congolense Infections and Treatment with Diminazene Aceturate

Trypanosomosis is a disease that causes extensive physiopathological effect in the blood and tissues which may affect normal immune response in the infected host. The condition is exacerbated by the seeming existence of some resistant strains of Trypanosoma brucei and Trypanosoma congolense) which have become a menace to chemotherapy in trypanosomosis. These challenges enabled the research into the impact of experimental infections of single Trypanosoma brucei (T. brucei) and Trypanosoma congolense (T. congolense) and response to treatment on primary and secondary humoral immune response to anti-rabies vaccination in dogs. Twelve (12) dogs grouped into 3 with 4 members each were used. Group 1 was the uninfected control, GPII was infected with T. congolense and GPIII was infected with T. brucei. Prior to infection, the experimental groups were first vaccinated with antirabies vaccine. Three weeks post vaccination both T.congolense and T. brucei infections were done on GPII and GPIII respectively. The prepatent period was 5.00 ± 1.30 days in T. brucei and was 14.00 ± 1.40 days in T. congolense infected groups. The serological results show that Rabies Passive Haemagglutination Test (RPHAT) could be used to assay for post antirabies vaccination antibody responses with reproducible results. A week post vaccination, the antibody titer in all the vaccinated groups (GPI, GPII, and GPIII) significantly increased (p < 0.05) and peaked at 3 weeks after vaccination. Subsequently, at week 7, there was a gradual significant decrease (p < 0.05) in the antibody production against rabies virus in the trypanosomes infected groups (GPII and GPIII). Treatment with diminazene aceturate did not significantly (p < 0.05) improve antibody response in the dogs. A secondary vaccination administered 12 weeks post- primary vaccination significantly increased (p < 0.05) the antibody titer with a peak at 3 weeks post- secondary vaccination. The study shows that both T. brucei and T. congolense suppress primary antibody response to vaccination which did not improve with treatment.