Detection of ovine respiratory syncytial virus in pneumonic lungs from apparently healthy sheep slaughtered at 5 abattoirs in Australia.

Respiratory disease is one of the main diseases of sheep in many regions globally. Respiratory syncytial virus (RSV) causes severe disease in humans and in calves, but little is known about the role of RSV in sheep. We studied the prevalence of ovine RSV in sheep processed at 5 abattoirs in southern Australia. Bronchial swab samples were collected from 182 consignments of lambs up to 12 months of age and 71 consignments of adult sheep; these were tested for the presence of the virus using a qPCR based on the F gene sequence. Six of the 253 abattoir consignments (2.4%) tested positive for ovine RSV. Four of the positive consignments were lambs and 2 were adult sheep. To our knowledge, this is the first report of the ovine strain of RSV in sheep with pneumonia from Australia. Further research is needed to clarify the role of RSV in pneumonia in sheep.

Les maladies respiratoires sont l'une des principales maladies des ovins dans de nombreuses régions du monde. Le virus respiratoire syncytial (VRS) provoque une maladie grave chez les humains et les veaux, mais on sait peu de choses sur le rôle du VRS chez les ovins. Nous avons étudié la prévalence du VRS ovin chez les moutons traités dans 5 abattoirs du sud de l'Australie. Des écouvillons bronchiques ont été prélevés sur 182 envois d'agneaux jusqu'à l'âge de 12 mois et 71 envois de moutons adultes; ceux-ci ont été testés pour la présence du virus à l'aide d'un qPCR basé sur la séquence du gène F. Six des 253 envois d'abattoirs (2,4 %) ont été testés positifs pour le VRS ovin. Quatre des envois positifs étaient des agneaux et 2 des ovins adultes. À notre connaissance, il s'agit du premier signalement de la souche ovine du VRS chez des moutons atteints de pneumonie en provenance d'Australie. Des recherches supplémentaires sont nécessaires pour clarifier le rôle du VRS dans la pneumonie chez le mouton.(Traduit par Docteur Serge Messier).

Molecular characterisation of the Australian and New Zealand livestock Chlamydia pecorum strains confirms novel but clonal ST23 in association with ovine foetal loss.

Chlamydia pecorum is a veterinary pathogen associated with abortions and perinatal mortality in sheep. Recent studies investigating foetal and perinatal lamb mortality in sheep from Australia and New Zealand identified C. pecorum clonal sequence type (ST)23 strains in aborted and stillborn lambs. Presently, there is limited genotypic information on C. pecorum strains associated with reproductive disease, although whole genome sequencing (WGS) of one abortigenic ST23 C. pecorum strain identified unique features, including a deletion in the CDS1 locus of the chlamydial plasmid. We applied WGS on two ST23 strains detected in aborted and stillborn lambs from Australia and used phylogenetic and comparative analyses to compare these to the other available C. pecorum genomes. To re-evaluate the genetic diversity of contemporary strains, we applied C. pecorum genotyping, and chlamydial plasmid sequencing to a range of C. pecorum positive samples and isolates from ewes, aborted foetuses and stillborn lambs, cattle and a goat from diverse geographical regions across Australia and New Zealand.The two new C. pecorum genomes are nearly identical to the genome of the Australian abortigenic strain including the unique deletion in the chlamydial plasmid. Genotyping revealed that these novel C. pecorum ST23 strains are widespread and associated with sheep abortions on Australian and New Zealand farms. In addition, a goat C. pecorum strain (denoted ST 304) from New Zealand was also characterised. This study expands the C. pecorum genome catalogue and describes a comprehensive molecular characterisation of the novel livestock ST23 strains associated with foetal and lamb mortality.

Seropositivity to Coxiella burnetii in primiparous and multiparous ewes from southern Australia: A cross-sectional study.

The role of infectious diseases including coxiellosis in causing poorer reproductive performance of primiparous ewes are not well studied. The aims of this study were to determine if natural exposure to Coxiella burnetii is widespread in breeding ewes and whether seropositivity is associated with poor reproductive performance of primiparous ewes. Seropositivity to Coxiella burnetii was 0.08% (CI95% 0.01, 0.36) in primiparous ewes and 0.36% (CI95% 0.07, 1.14) in mature ewes. Coxiella burnetii was not detected in aborted or stillborn lambs using qPCR. These findings suggest C. burnetii infection was unlikely to be an important contributor to abortion and perinatal mortalities observed for primiparous ewe flocks, and exposure to C. burnetii was not widespread in ewes on farms located over wide geographical region of southern Australia. Whilst ewes on these farms were not an important reservoir for C. burnetii, sporadic zoonotic transmission from sheep is reported and has public health implications.

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

Traditional methods of detecting Chlamydia pecorum in tissue samples such as polymerase chain reaction or cell culture are laborious and costly. We evaluated the use of a previously developed C. pecorum LAMP assay using minimally processed ovine samples. Cotyledon (n = 16), foetal liver (n = 22), foetal lung (n = 2), and vaginal (n = 6) swabs, in addition to cotyledon (n = 6) and foetal liver (n = 8) tissue samples, were rapidly processed and used for LAMP testing without DNA extraction. Overall, LAMP test results were highly congruent with the in-house reference qPCR, with 80.43% (37/46; 72.73% positive agreement (PA); 84.75% negative agreement (NA)) overall agreeance for swab samples, and 85.71% (12/14; 80% PA; 88.89% NA) overall agreeance for tissue samples. Out of the 11 total discrepant results, discrepancy was mainly observed in samples (n = 10) with less than 100 copies/µL C. pecorum DNA. While sensitivity could be improved, the simplicity, low cost, and accuracy of detection makes this test amenable for use at point-of-care for detecting C. pecorum in sheep.

Chlamydia pecorum detection in aborted and stillborn lambs from Western Australia.

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.

Chlamydia pecorum-Induced Arthritis in Experimentally and Naturally Infected Sheep.

Chlamydia pecorum is an obligate intracellular pathogen with a wide host range including livestock such as sheep, cattle, goats, and pigs as well as wildlife species such as koalas. Chlamydial polyarthritis is an economically important disease resulting in swollen joints, lameness, stiffness, and weight loss in young sheep. In the present study, tissues from sheep experimentally or naturally infected with Chlamydia pecorum were assessed by histopathology and immunohistochemistry. Carpal, hock, and stifle joints as well as spleen, liver, kidney, lymph nodes, lung, and brain of 35 sheep from different inoculation groups were available. Two different C. pecorum strains (IPA and E58), different routes of administration (intraarticular or intravenous), UVA-irradiated IPA strain, and corresponding noninfected control groups were investigated. Similar investigations on tissues from 5 naturally infected sheep were performed. The most obvious inflammatory lesions were observed in synovial tissues and, notably, in the renal pelvis from the experimentally infected group and naturally infected animals. This resulted in chronic or chronic-active arthritis and pyelitis. Intralesional chlamydial inclusions could be demonstrated by immunohistochemistry in both tissues. Immunohistochemical evaluation of the presence and distribution of macrophages, T and B cells in synovial tissues revealed macrophages as the most prevalent inflammatory cell population. Previous observations indicated that C. pecorum isolates can infect circulating monocytes. Together with the finding of the histological lesions in synovial tissues and internal organs alongside the presence of C. pecorum DNA, these observations suggest chlamydial arthritis in lambs is the result of hematogeneous spread of C. pecorum.