Rabies serosurvey of domestic dogs in Kigali City, Rwanda

In Rwanda, rabies is a threat to public health and the control is mainly done by vaccinating pet dogs annually. However, it is unknown whether dogs that received rabies vaccination achieved protective antibody levels. This study assessed factors influencing rabies antibody titres in vaccinated and non-vaccinated pet dogs in Kigali City, Rwanda. A questionnaire was used to gather information on 137 study dogs and clotted blood samples were collected from 93 healthy pet dogs. Enzyme-Linked Immunosorbent Assay (ELISA) was used to quantify rabies antibody titres. Frequency and geometric mean titres, as well as chi-square and regression analysis, were used to study the data. The results showed that 35% of the vaccinated dogs had antibody titres below 0.5 EU/ml while 53.8% of the non-vaccinated dogs had detectable antibodies varying between 0.133 and 0.238 EU/ml. All types of rabies vaccine (A, B, C, D, and E) used elicited diverse antibody levels and the overall mean titre was 1.071. Vaccinated dogs had a higher mean number of rabies antibodies (11.776059735) than non-vaccinated dogs (1.41579378). Mean titres decreased with time between vaccination and sampling, that is, 1.559, 0.949, and 0.934 in dogs sampled 1-5, 6-9 and 10-12 months following vaccination, respectively. The mean titres increased steadily from the first to the fourth vaccination times, namely 0.608, 1.320, 1,395, and 1.787, respectively. Mean titres increased with dogs’ age and varied between 0.638 and 1.515. Factors including vaccination status, number of vaccination, time elapsed between vaccination and sampling, and age at vaccination influenced rabies antibody titres. Irrespective of the type of rabies vaccine applied, 99% of vaccinated dogs produced rabies antibodies though not all had protective levels. Considering the high number of vaccinated dogs that were poor responders to rabies vaccination, further studies should be undertaken to investigate and understand the phenomenon.