Central West Local Land Services, Dubbo, NSW, 2830, Australia; Centre for Animal Health Innovation, University of the Sunshine Coast, Sippy Downs, QLD, 4556, Australia.
Centre for Animal Health Innovation, University of the Sunshine Coast, Sippy Downs, QLD, 4556, Australia.
Vet Microbiol. 2018 Apr;217:90-96. doi: 10.1016/j.vetmic.2018.03.009. Epub 2018 Mar 10.
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.
绵羊衣原体是一种全球性的家畜病原体，能够引起绵羊和牛的严重和经济上重大的疾病，如关节炎。关于疾病的临床进展和绵羊无症状和有症状衣原体病的长期影响，相对较少的信息。最近在犊牛中的研究表明，地方性衣原体感染可能会降低生长速度。为了研究澳大利亚商业羔羊群中地方性衣原体感染的临床健康参数和生产影响，我们对 105 只从 2 到 10 个月大的边境莱斯特羔羊进行了两个月一次的采样和临床健康评估。通过血清学和种特异性定量 PCR 调查衣原体状况。在整个研究期间，结膜炎仍然是一个持续的临床特征，而关节炎（例如可触及的滑膜关节积液）的迹象在一部分羔羊中得到缓解，而在其他羔羊中则持续存在。临床疾病和衣原体感染在 6 个月大（断奶）时最高。如前所述，峰值血清转化倾向于在临床症状出现后两个月发生（6 个月龄），尽管此时仍存在疾病，但羔羊在 10 个月龄时清除衣原体感染。值得注意的是，衣原体感染的存在并没有影响整个研究期间羔羊的体重或生长速度。在剖检时，慢性关节炎羔羊的关节中未检测到衣原体。对该羊群中菌株的分子分析表明，该羊群中循环的感染菌株是克隆性衣原体病原体，称为 ST23，通常与澳大利亚绵羊的结膜炎和多发性关节炎有关。这项研究为进一步研究绵羊衣原体感染的流行病学和疾病传播动态提供了一个平台。
