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Understanding the health and production impacts of endemic Chlamydia pecorum infections in lambs
journal contributionposted on 2023-05-21, 06:56 authored by Walker, E, Jelocnik, M, Bommana, S, Timms, P, Scott CarverScott Carver, Polkinghorne, A
Lamydia pecorum is a globally recognised livestock pathogen that is capable of causing severe and economically significant diseases such as arthritis in sheep and cattle. Relatively little information is available on the clinical progression of disease and the long-term effects of asymptomatic and symptomatic chlamydiosis in sheep. Recent studies in calves indicate that endemic C. pecorum infections may reduce growth rates. To investigate the clinical health parameters and production impacts of endemic C. pecorum infection in an Australian commercial lamb flock, we performed bimonthly sampling and clinical health assessments on 105 Border Leicester lambs from two to ten months of age. Chlamydial status was investigated via serology and species-specific quantitative PCR. Throughout the study period, conjunctivitis remained a persistent clinical feature while signs of arthritis (e.g. palpable synovial joint effusions) resolved in a subset of lambs while persisting in others. Clinical disease and C. pecorum infection were highest at six months of age (weaning). As previously reported, peak seroconversion tends to occur two months after the onset of clinical symptoms (6 months of age), with lambs clearing chlamydial infection by 10 months of age, despite ongoing disease still being present at this time. Notably, the presence of chlamydial infection did not affect lamb mass or growth rates throughout the study. At necropsy, C. pecorum was not detected within the joints of lambs with chronic arthritis. Molecular analysis of the strains in this flock suggest that the infecting strains circulating in this flock are clonal C. pecorum pathotypes, denoted ST 23, commonly associated with conjunctivitis and polyarthritis in Australian sheep. This study provides a platform for further research in the epidemiology and disease transmission dynamics of C. pecorum infections in sheep.
Australian Research Council
Central West Livestock Health and Pest Authority
McGarvie Smith Institute
NSW Department of Primary Industry
Tablelands Livestock Health and Pest Authority
University of the Sunshine Coast
Publication titleVeterinary Microbiology
Department/SchoolSchool of Natural Sciences
PublisherElsevier Science Bv
Place of publicationPo Box 211, Amsterdam, Netherlands, 1000 Ae
Rights statement© 2018 Published by Elsevier B.V.