Sequential Monitoring of Pre-exposure Antirabies Vaccinal Neutralizing Antibodies in Dogs

Abstract

Background: Effective animal vaccines against Rabies that provide a considerable duration of immunity and mass parenteral vaccination programmes remain the mainstay of canine rabies control. Animal birth control (ABC) programmes coupled with pre-exposure anti-rabies vaccination with booster dose at regular interval have been advocated as a method to control urban street male and female dog populations and ultimately human rabies in Asia. The present study is aimed to determine the persistence of antirabies neutralizing antibodies to pre-exposure vaccination in dogs and the effect of booster vaccination on pre-exposure antirabies vaccinal neutralizing antibody levels. Methods: The study was conducted in 30 non-descript dogs which were divided into two groups containing 15 animals each. Dogs in group I were given pre exposure prophylaxis with booster dose after 21 days and animals in group II were given primary vaccination without any booster dose. Serum samples were collected at 0th, 7th, 14th, 21st, 28th, 60th, 90th and 120th days post vaccination. Seromonitoring of antirabies vaccinal antibodies was done in both groups by RFFIT. Result: 80 per cent of the animals in group I were able to maintain the mean antibody titre above protective level upto 4 months successfully, whereas, 40 per cent of the animals in group II were able to maintain mean antibody titer above protective level only upto 2 months. With the inactivated vaccine, booster dose given three weeks after the primary vaccination has ensured levels of neutralizing antibodies greater than 0.5 IU/ml for a period of at least four months.