Relationships between the shedding of Coxiella burnetii, clinical signs and serological responses of 34 sheep

Two abortions associated with Coxiella burnetii occurred in a group of 34 p regnant ewes. The seroprevalence of C Burnetii infection was studied by usi ng an ELISA and the immunofluorescence (IF) assay was applied to the conten ts of vaginal swabs. In addition, a PCR assay, with primers based on a tran sposonlike repetitive region of the C burnetii genome (trans-PCR), was used for the highly sensitive and specific detection of C burnetii in vaginal s wabs, milk and faeces. Of the 34 animals tested at parturition, eight (24 p er cent) were positive by ELISA, 11 (32 per cent) were positive by IF, and 15 (44 per cent) were positive when the vaginal swab extract was subjected to the trans-pea assay C burnetii was therefore detected by PCR in the vagi nal swabs of seven seronegative ewes. However, five weeks after lambing, 16 (47 per cent) of the animals tested were ELISA positive but only two anima ls (6 per cent) were positive by PCR. Among the ELISA- and PCR-positive ani mals, eight (25 per cent) shed coxiella in their milk and six (18 per cent) did so in their faeces.