Rabies Antibody Titer Survey among Post-rabies Vaccinated Dogs Imported to Israel

Assessing immunity level of humans and animals is important for preventive medicine research and regulation. A minimum serum level of 0.5 IU/mL rabies neutralizing antibodies (RFFIT) is considered the minimum protective level against rabies. Identifying risk factors for low antibody levels is necessary for debating and understanding the vaccination policy in Israel and worldwide. This policy has public health and animal welfare implications. In our study we have examined serum of 109 dogs imported to Israel, vaccinated at least once against rabies, ≥30 days prior to the test. The risk factor for test failure (antibody level lower than threshold) was a single vaccination during the dog`s life. Background factors, including importation from non-OECD countries and being of pure breed were examined as well. Fisher exact test was used to examine these factors. Of the 109 dogs, 59 have been vaccinated only once against rabies, of which 21 (36%) have failed the test. This was found significant with failing the test (P <0.001). Background factors were not associated with failing the test. In one dog, antibody titer was ≤0.5 IU/mL even after three consecutive rabies vaccinations.This dog belongs to a group of dogs known as "Non-responders". In conclusion, we found a significant association between low anti-rabies antibody titer and an only single rabies vaccination in dogs imported to Israel. Similar findings were also in a previous survey conducted among dogs examined pre-exportation. The results reinforce a regulatory decision to add a rabies vaccination "booster" for dogs after the first rabies vaccination.