Seropositivity to Toxoplasma infection in sheep samples submitted to Animal and Plant Health Agency laboratories between 2005 and 2012.

Ovine serum samples submitted to Animal and Plant Health Agency (APHA) (formerly the Animal Health and Veterinary Laboratories Agency) – Weybridge regional laboratories in England and Wales for diagnostic and monitoring purposes between 2005 and 2012 were investigated for possible spatial and temporal variations in seropositivity to Toxoplasma gondii infection. Of the 4354 samples tested by latex agglutination, 2361 (54.2 per cent) were seropositive. No correlation between seropositivity and climatic conditions was identified by mixed-effects modelling using meteorological data summaries. The proportion of seropositive samples collected during November was found to be significantly lower than those collected during other months and samples from the North West England and North Wales Regions had significantly lower odds of being positive. Spatial cluster analysis identified a significantly higher proportion of seropositive animals in East Anglia and the South, East and Midlands of England. Spatio-temporal cluster analysis detected a single significant cluster of seropositive animals dating from January 2006 to January 2011, which covered a large proportion of the farm locations. As well as confirming high overall levels of infection within the national flock, these findings also indicate possible temporal and regional variations in exposure of sheep to T. gondii .