Investigation of protective level of rabies antibodies in vaccinated dogs in Chennai, India

Abstract

Background Rabies is still endemic in India causing an estimated 20,000 human deaths a year. Free roaming dogs and unvaccinated owned dogs play a major role in the maintenance of the disease. Dog vaccination is the most crucial aspect of rabies prevention and control strategies; therefore vaccine immunogenicity and longevity are important determinants of the efficiency of rabies control efforts. Methods In this study at Madras Veterinary College, India, a total of 297 serum samples were collected from owned dogs that were vaccinated against rabies. Data regarding age, gender, breed, neuter status and last date of vaccination were collected at the time of blood collection. The level of rabies virus neutralising antibodies in the sera of these dogs was measured through rapid focus fluorescence inhibition test. The factors associated with protective level of rabies antibodies in vaccinated dogs were investigated through multivariable regression analysis. Results This cross‐sectional investigation shows that only 40% (119/297) of the all the dogs in the study showed presence of protective level of anti‐rabies antibodies, and 40% (72/180) of the dogs vaccinated within the last year showed presence of protective levels of antibodies causing concern about rabies vaccine quality and its impact on rabies control. The study also shows that older and neutered dogs are more likely to have protective titre among vaccinated dogs, while non‐descript breed dogs are less likely to have a protective titre compared to pure breeds. Conclusion In this study 60% (108/180) of young prima dogs and adult dogs did not show protective levels of antibodies within the year of last rabies vaccination, although they had previous vaccination history. This high percentage of apparent non‐responders is a cause of concern of administration, distribution, storage, potency and quality management of vaccines in India.

Dog Population Rabies Immunity before a Mass Vaccination Campaign in Lima, Peru: Vulnerabilities for Virus Reestablishment

“…found that purebreds are more likely to seroconvert. 54 We found similar trends to other previous studies as well ( Figure 1D ), but these trends were not statistically significant. One potential explanation for the higher rabies antibody titers found in females and small/medium dogs is that they are easier to handle and therefore are vaccinated more frequently than larger or male dogs.…”

Factors Involved in the Immunological Protection against Rabies Virus in Dogs in Spain

“…Another conclusion drawn from the results of this study is that unsterilized males are more likely to be unprotected. A recent study in India supports these conclusions, showing that neutered dogs are approximately four times more likely to present antibody titers than unsterilized dogs [71]. Thus, it is indisputable that an animal's reproductive status and hormones, mainly testosterone, influence the immune response [72].…”

A Comparative Evaluation of the Estimation of Rabies Virus Antibodies among Free-Roaming, Vaccinated Dogs in Bengaluru, India

“…An earlier study from Chandigarh, India, observed that only 1% of street dogs had adequate titres [ 22 ], as evaluated by using a commercially available ELISA. Another sero-surveillance study using an iELISA from Mumbai showed an overall low seroprevalence of anti-RABV antibody in stray dogs at the level of 39.2% [ 23 ] and a study from Chennai revealed an inadequate titre in 60% of vaccinated dogs [ 24 ]. Similar results of inadequate levels (i.e., 62%) have been reported in stray dogs in Bangkok, where a commercial ELISA was used [ 25 ].…”