Post-exposure prophylaxis (PEP) of rabies-infected Indian street dogs.

A rabies post-exposure prophylaxis study was carried out to examine the efficacy of two commercially available rabies vaccines and the efficacy of a 5- or 3-dose vaccination regime. Healthy, native breed dogs (N = 40), seronegative for rabies antibody, were challenged intramuscularly with virulent rabies virus brain suspension (10(4.4) MLD50) by direct inoculation into the masseter muscle. The dogs were divided into four equal groups and injected intramuscularly with either Nobivac Rabies (Intervet), Rabisin (Merial) or placebo on multiple occasions (3 or 5-times) over the next 28 days. All dogs were confined in their respective groups for 90 days post-challenge and observed for the development of any clinical signs. Serum samples were assayed for rabies antibody using both the Rapid Fluorescent Focus Inhibition Test (RFFIT) and the Enzyme Linked Immunosorbent Assay (ELISA). None of the vaccinated dogs showed any clinical signs of rabies at any stage of the study. All of their brain tissue samples taken at the end of the study were found negative for rabies viral antigen. Six of the dogs in the control group showed signs of either furious or dumb rabies and died before the end of the study. In all these dogs the diagnosis of rabies was confirmed by means of a specific fluorescent antibody test (FAT) and by the presence of Negri-bodies in brain smears. Four control dogs survived after mild and transient clinical signs showing protective titers at the end of the trial (day 90). Their brain samples were negative for Negri-bodies and in the FAT. Both vaccines were found to be safe and effective in preventing rabies when inoculated intramuscularly applying the 5-dose regime (0, 3, 7, 14 and 28 days). Limited by space only one vaccine could also be tested in a 3-dose schedule. Using this 3-dose regime (0, 5 and 28 days) Nobivac Rabies was also found to be safe and effective in preventing rabies. All vaccinated dogs responded with antibody titers > 0.5 IU by 7 days.