An Assessment of Immune Response to Canine Distemper Vaccination in Dogs Experimentally Infected with Ancylostoma and Trypanosome Parasites

The immunological alteration in vaccinated dogs with single hookworm, Ancylostoma caninum (A. c) and conjunct infection with Trypanosoma congolense (T. c) and Trypanosoma brucei (T. b) was determined. Sixteen dogs grouped into 4 of 4 members each were used. Group 1 was the uninfected control, GPII was infected with A. c, GPIII was infected with A. c /T. c, and GPIV was infected with T. b/A. c. The dogs were first inoculated with canine distemper (CD) vaccine before infection with A. c 4 weeks post vaccination. Two weeks later, both GPIII and GPIV were superposed with trypanosome infection. Prepatent period of A. c was 14 to 16 days in single A. c group and 13 to 14 days in conjunct trypanosome/A. c. The prepatent period of conjunct T. c/A. c was 9.00±1.10 days and 3.00±1.40 days, in conjunct T.bb/A. c. The protective antibody against CDV was considered using haemagglutination inhibition test (HIT) titer >100 as a cut off for sero-conversion. At one week post vaccinations, the antibody titer against canine distemper (CDV) and anti-rabies in all the vaccinated groups (GPI, GPII, GPIII, and GPIV) significantly increased (p<0.05) and peaked at 3 weeks post vaccination. Subsequently, there was gradual significant decrease (p<0.05) in all the infected groups (GPII, GPIII and GPIV). The decrease in the conjunct groups (GPIII and GPIV) was higher compared to the single infections (GPII). Treatment with diminazene aceturate and mebendazole in all the groups did not significantly (p<0.05) improve antibody response in the dogs. A secondary vaccination administered at 12 weeks post- primary vaccination significantly increased (p<0.05) the antibody titer with a peak 3 weeks post- secondary vaccination. In conclusion, both trypanosomes and A. c induced primary immune suppression in antibody response to vaccination which improved on secondary vaccination in the infected dogs.