Serological survey of leptospiral antibodies in sheep from England and Wales.

A total of 3722 sera was obtained from 188 flocks widely distributed throughout England and Wales; three sera were randomly selected from each flock and tested in the microscopic agglutination test for leptospiral antibodies. Infection with leptospires of the Hebdomadis serogroup was found to the widespread and it is probable that the infecting serovar is hardjo. The prevalence of hardjo titres in the random survey was 6.4 per cent and within-herd prevalences ranged up to 94.4 per cent. Titres to autumnalis antigen were found in 7.3 per cent of sera and evidence is presented that suggests a proportion of these titres are cross-reactions with agglutinins stimulated by infection with leptospires from other serogroups. Titres to bratislava antigen (Australis serogroup) were found in 3.4 per cent of sera. Within-herd prevalences of autumnalis and bratislava titres did not range above 16.7 per cent and 26.3 per cent respectively.