Vol. 13, Issue 3 (2024)

Rabies is one of the most fatal zoonotic diseases that have tormented humans and is still a significant public health problem in many parts of the globe. Dogs are the reservoir of rabies in most rabies-endemic countries around the world. Animal vaccination is a key factor for rabies prevention and control of virus transmission. In Kerala, even though prophylactic vaccinations are being done regularly in dogs, seroconversion studies are not being undertaken and the effects of these vaccinations are not being assessed. Hence the present study was conducted with the objectives to assess the seroconversion following prophylactic anti-rabies vaccination in dogs using Indirect ELISA test and to validate Indirect ELISA in assessing post vaccinal seroconversion using RFFIT as the gold standard.

The study was taken up as a cross-sectional study on dogs above 3 months of age. A total of 116 samples were made part of the study. Out of the 116 samples studied 77 (66.4%) of animals were protected and 39 (33.6%) were unprotected. Among the vaccinated animals, 77 (71.3%) of the study subjects had protective titre. The study demonstrated that a single dose of rabies vaccine did not elicit adequate antibody levels in majority of dogs sufficient to give protection beyond one year. The protective efficacy of vaccine can be influenced by various associated factors viz. age, sex, breed, vaccine brand, months since vaccination, number of vaccinations received etc

When animals were given only one vaccine in the first year of life, data indicates that it is not sufficient for the maintenance of antibody titres until the time of annual booster vaccination. The regularly vaccinated group which received more than two vaccine doses, protective titre was seen maintained beyond one year: whereas those animals which had received a single vaccination couldn't maintain their titre for one year.

In the multivariable analyses of the present study, the history of 2 or more vaccination was the only factor significantly associated with the proportion of binding antibody titres ≥0.5 EU/ml More studies with larger sample sizes are recommended to assess the statistical significance of each associated factors viz. age, sex, breed, vaccine brand, months since vaccination, number of vaccinations received etc on the immune response following antirabies vaccination. The study findings indicate a recommendation for booster dose after primary dose, annual boosters and vaccination campaigns which are necessary to maintain adequate protection levels and herd immunity. Moreover, we can infer that a quantitative ELISA may be a complementary tool for sero-monitoring immune responses of dogs and cats after rabies vaccination.