The Thai Journal of Veterinary Medicine


A 210-day trial was undertaken in northern Thailand to compare the serological responses of 6 to 18 month-old cattle and buffalo to 2 different vaccination regimes using a trivalent O, A and Asia 1 vaccine. Animals were pair matched and randomly allocated into one of 2 groups. Group 1 was vaccinated on days 0 and 180 and group 2 was vaccinated on days 0, 30 and 180. Blood samples were collected from both groups on days 0, 30, 60, 180 and antibody titres measured by the serum neutralisation test (SNT). Group 2 had significantly higher mean titres and percentage of animals protected (defined as animals with log, reciprocal SNT titres > = 1.5) to all 3 serotypes at day 60 (p < 0.05). At day 180, group 2 had significantly higher mean titres to serotypes O and A (p < 0.05) but not to Asia 1 and there were no differences between the groups in the percentage of animals protected for any of the serotypes. At day 210, there were no significant differences in mean titres between the groups (p > 0.05) and all animals groups had protective titres to all serotypes. It was concluded that to fully realise the advantage of the improved response to a primary course of 2 inoculations, a vaccination interval of shorter than 6 months is required.

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