Immunogenicity and efficacy of Rabivac vaccine for animal rabies control in Morocco

ABSTRACT

PURPOSE: To fight animal rabies, Moroccan veterinary authorities organize annual dog mass vaccination campaigns using Rabivac vaccine, an inactivated adjuvanted cell culture veterinary rabies vaccine. Two experiments were undertaken to assess the efficacy and immunogenicity of Rabivac. MATERIALS AND METHODS: The first experiment involved 13 caged dogs (8 vaccinated and 5 negative controls). Dogs were bled at day 0 (D0) and at days D7, D14, D21, D28, D35, D49, D56, D64, D70, D77, D84, D91, D98, D105, D112, and D119 post-vaccination. At D121, a virulent challenge was performed. After 70 days monitoring period, seven out of eight vaccinated dogs survived the challenge (one dog succumbed to a mesenteric torsion accident) and four out of five controls succumbed. All vaccinated dogs seroconverted and the control dogs remained negative. The second experiment consisted in a field study involving 919 owned dogs randomly selected in eight Moroccan districts located in different parts of the country. The dogs were identified and vaccinated by the parenteral route and bled on the vaccination day (D0) and on D30. RESULTS: Ninety-two percent of dogs developed a positive rabies virus neutralizing antibody response to vaccination and 24% were positive at D0, suggesting that dogs were previously vaccinated. The increase in rabies antibody titers was highly significant in all districts. No significant difference seemed occurring between the geographical status (rural, semiurban, or urban) of the districts on the results obtained. CONCLUSION: Rabivac is efficacious both in experimental and field conditions. This supports its use in dog mass vaccination campaigns.