Studies of antibody titres in experimentally induced ovine toxoplasmosis.

Analysis of serological data from 63 experimentally infected sheep showed an inverse relationship between rise in toxoplasma indirect haemagglutination (IHA) titre after infection and titre at the time of infection. It was observed that, on average, sheep with a preinfection IHA titre of 1:200 or higher did not exhibit a significant rise in titre after infection. The ratio of toxoplasma antibody titres measured by the IHA and dye tests and the ratio of IHA titres in the IgM and IgG antibody fractions were shown to vary according to the duration of infection indicating that serological techniques could be developed to distinguish between latent and acute ovine toxoplasmosis.