Chlamydia pecorum detection in aborted and stillborn lambs from Western Australia

Abstract

Lamb survival is an important welfare and productivity issue for sheep industries worldwide. Lower lamb survival has been reported for primiparous ewes, but the causes of this are not well studied. The aim of this study was to determine causes of perinatal deaths for lambs born to primiparous ewes in Western Australia, and identify if infectious diseases are implicated. Lamb mortality from birth to marking were determined for 11 primiparous ewe flocks on 10 farms in Western Australia. Lamb mortality from birth to marking averaged 14% for single-born and 26% for multiple-born lambs. Lamb necropsies (n = 298) identified starvation–mismosthering–exposure (34%), dystocia (24%) and stillbirth (15%) as the most common causes of perinatal lamb death. There was no evidence of exotic abortigenic pathogens in aborted and stillborn lambs (n = 35). Chlamydia pecorum was detected by qPCR in 15/35 aborted and stillborn lambs on 5/6 farms. Preliminary molecular characterisation of C. pecorum detected in samples from aborted and stillborn lambs (n = 8) using both Multilocus Sequence Typing and ompA genotyping indicated all strains were genetically identical to previously described pathogenic livestock strains, denoted ST23, and dissimilar to gastrointestinal strains. High frequency of detection of a pathogenic C. pecorum strains ST23 associated with ovine abortion and stillbirth on multiple farms located across a wide geographic area has not been previously reported. Chlamydia pecorum may contribute to reproductive wastage for primiparous sheep in Western Australia. Further investigation to understand C. pecorum epidemiology and impact on sheep reproduction is warranted.

Real-Time Fluorometric Isothermal LAMP Assay for Detection of Chlamydia pecorum in Rapidly Processed Ovine Abortion Samples: A Veterinary Practitioner’s Perspective

“…Firstly, LAMP does not distinguish pathogenic from non-pathogenic C. pecorum strains. This is also a limitation of currently available C. pecorum qPCRs [ 8 ], and is especially a concern for aborted material, which can easily be contaminated with non-pathogenic gastrointestinal C. pecorum strains. Nevertheless, the benefit of using C. pecorum detection by LAMP with the rapid swab processing protocol described by Jelocnik et al [ 12 ] is that residual swab suspension can be used for DNA extraction and molecular characterisation, unlike other protocols described for rapid swab processing for C. pecorum LAMP [ 13 ].…”

“…This study used retrospective frozen tissue samples from ovine abortion and stillbirth investigations that were collected between 2018 and 2019 as part of a previous study where C. pecorum was detected [ 8 ] and was approved by Murdoch University Animal Ethics Committee (R3004/17). The testing and use of these tissues were approved by University of the Sunshine Coast Animal Ethics approval exemption (ANE2057).…”

“…However, this organism is also frequently detected in the faeces of apparently healthy sheep [ 6 , 7 ]. Recently, C. pecorum has been implicated in cases of ovine abortion across Australia, with diagnosis aided by bacterial isolation and/or nucleic acid amplification assays performed in specialised diagnostic laboratories [ 8 , 9 ]. While these methods are considered the ‘gold-standard’ for detecting and diagnosing C. pecorum , they are laborious, time-consuming, and costly [ 10 ].…”

“…Considering the emerging evidence for the abortigenic potential of C. pecorum infections in sheep [ 8 , 9 , 15 ], a rapid diagnosis would offer effective on-farm surveillance, improve biosecurity, and aid in infection control [ 14 ]. While the rapid swab processing and isothermal testing has been evaluated for koala C. pecorum detection, there is a paucity of reports for the use of these in diagnosing C. pecorum infections in sheep.…”

An Accessible Diagnostic Toolbox to Detect Bacterial Causes of Ovine and Caprine Abortion

“…were found, although in these cases, histological signs of inflammation were not found, and therefore the role of these agents in the etiology of abortions is unclear. Nevertheless, C. pecorum has incidentally been described as a possible cause of small ruminant abortion [12,13]. Other major causes of abortions were Campylobacter spp., Listeria spp., Toxoplasma gondii, Escherichia coli, and Yersinia enterocolitica.…”