Detection of Coxiella burnetii in placenta and abortion samples from British ruminants using real-time PCR

A real-time PCR was developed to detect Coxiella burnetii (the cause of Q fever) in ruminant placentas and aborted fetuses. Primer and probe sets previously developed for human tissue studies were used to target the insertion sequence IS 1111 gene for C burnetii . The assay was highly sensitive, with a limit of detection of 10 copies of template, theoretically equating to a single bacterium, and did not cross-react with a panel of other bacteria. To determine sensitivity on field samples submitted for the diagnosis of abortion, results using the IS 1111 PCR assay were compared with a com 1 PCR assay. When applied to ruminant abortion material, including placental cotyledons and fetal samples, the IS 1111 and com 1 assays yielded positive results in 23 (25 per cent) of 93 and 19 (20 per cent) of 93 samples, respectively. One infected goat herd was monitored for 31 months: 57 (92 per cent) of 62 placental cotyledon samples from aborting and non-aborting goats, and 10 (30 per cent) of 33 fetal samples were positive by the IS 1111 PCR assay.