CASE NOTES

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Chlamydia pecorum abortion in sheep

Pedro Pinczowski, NSW Department of Primary Industries, Biosecurity & Food Safety, EMAI, Menangle NSW

Posted Flock & Herd December 2021

Despite previous detection of Chlamydia pecorum in sporadic ovine abortions, published descriptions of naturally occurring infections with foetoplacental lesions are lacking. This report describes severe necrosuppurative placentitis with vasculitis, and foetal pyelonephritis and enteritis in late-term abortions of maiden ewes. Chlamydial infection was detected using a Chlamydia genus-specific qPCR (quantitative polymerase chain reaction) on tissue extracts from 3 foetuses. C. pecorum was identified using a targeted qPCR assay, which also determined infectious load within foetal tissues. The presence of viable C. pecorum in foetal samples was confirmed by cell culture. Multilocus sequence typing (MLST) data indicated that the C. pecorum strains from each foetus were identical and of sequence type (ST) 23. Chlamydia sp. immunohistochemistry showed strong positive immunolabelling of foetoplacental lesions. Other infectious abortigenic agents were excluded with specific testing. This report confirms C. pecorum as a cause of ovine abortion and provides the first descriptions of associated foetoplacental lesions in naturally infected sheep.