Letters to the Editor

Abstract

Extract

Sir:- A paper entitled “An unusual response in cattle after use of a commercial leptospiral combined hardjo-pomona vaccine” by D.R. Ris and K.L. Hamel appears elsewhere in this Journal. Mr. Ris has brought to our attention that the extremely high post-vaccination titres that he observed are at variance with the moderate to low titres observed in experiments conducted in thih Department using the same brand of vaccine.⁽¹⁾⁽²⁾ The post-vaccination titres reported by Messrs. Ris and Hamel are to the best of our knowledge hither than any ever reported in the world literature as being associated with vaccination. Mr. Ris kindly made available to us some sera and we were able to subject them to the microscopic agglutination test (MAT) in our own laboratory. The number available to us was very small and insufficient to draw significant comparisons between our respective laboratories which in any case use different methods for conductins the M.A.T. However it is of interest that the two high-titre sera supplied to us both gave much lower titres when tested in our own and another laboratory. Leaving aside the observation that it is likely that the more effective the vaccine the higher the level of antibody it will produce. there is little point in debating the significance or otherwise of any particular titre until precision standard sera are available and adequate qualitv control can be instituted.