Preliminary field trails with a streptomycin-dependent vaccine against haemorrhagic septicaemia

In two trials, 68 cattle and buffalo calves, four to 10 months of age, were vaccinated with a vaccine containing a live streptomycin dependent mutant of Pasteurella multocida type B, isolated in Sri Lanka. Immunity was assessed using the passive protection test in mice with cattle and buffalo sera before and two or three weeks after vaccination. A single dose of vaccine conferred immunity in 66.6 to 83.3 per cent of cattle and 100 per cent of buffalo calves. A booster dose given three weeks later enhanced the immunity in cattle. There was no significant difference in the response, whether the vaccine was administered by the subcutaneous or intramuscular route. No adverse reactions were observed in any of the vaccinated animals.