Effect of age on anti-rabies immune response in pet dogs of Thrissur district, Kerala, India: a cross-sectional study

Kerala has recently experienced a surge in rabies cases despite ongoing vaccination efforts, prompting a need to assess the efficiency of these vaccinations. This cross-sectional study evaluated the effect of age on post-vaccination rabies antibody levels in 250 pet dogs in Thrissur district. Dogs were categorised into three: less than one year, one to five years, and above five years, and the immune response was measured using an indirect ELISA. The study found that 76.4 per cent of the dogs had protective antibody titres (≥0.5 EU/mL) with an average titre of 2.04 EU/mL. Dogs over five years had the highest seroconversion rate (92.3 per cent), while the younger age groups showed comparatively lower rates. Age significantly influenced vaccine response, while multiple-dose recipients showed higher protection than single-dose recipients. The study underscores the importance of booster doses and regular sero-monitoring for effective rabies control. Keywords: Anti-rabies vaccination, age, iELISA, antibody titre