Lawsonia intracellularis is an obligate intracellular bacterium associated with enteric disease in pigs. Clinical signs include weight loss, diarrhea, and, in some cases, sudden death. The hallmark lesion is the thickening of the intestinal mucosa caused by increased epithelial cell replication, known as proliferative enteropathy. The immune response to L. intracellularis is not well defined, and detection of the infection, especially in the early stages, is still a significant challenge. We review here the main approaches used to identify this important but poorly understood pathogen. Detection of L. intracellularis infection as the cause of clinical disease is confounded by the high prevalence of the pathogen in many countries and that several other pathogens can produce similar clinical signs. A single L. intracellularis–specific ELISA and several amplification assays are available commercially to aid detection and surveillance, although histopathology remains the primary way to reach a conclusive diagnosis. There are major gaps in our understanding of L. intracellularis pathogenesis, especially how the host responds to infection and the factors that drive infection toward different clinical outcomes. Knowledge of pathogenesis will increase the predictive value of antemortem tests to guide appropriate interventions, including identification and treatment of subclinically affected pigs in the early stages of disease, given that this important manifestation reduces pig productivity and contributes to the economic burden of L. intracellularis worldwide.

细胞内劳森菌是与猪肠道疾病相关的专性细胞内细菌。临床体征包括体重减轻，腹泻，在某些情况下还包括猝死。标志性病变是由上皮细胞复制增加引起的肠粘膜增厚，称为增生性肠病。对细胞内劳森氏菌的免疫应答尚不明确，尤其是在早期阶段，检测感染仍是一项重大挑战。我们在这里回顾了用于识别这种重要但知之甚少的病原体的主要方法。细胞内劳森氏菌的检测在许多国家，致病菌的高流行使感染作为临床疾病的原因感到困惑，而其他几种病原菌也可能产生类似的临床症状。尽管组织病理学仍然是达成结论性诊断的主要方法，但商业上可以使用一种细胞内劳森氏菌特异性ELISA和几种扩增测定法来辅助检测和监测。我们对胞内劳森氏菌的理解存在重大差距发病机理，尤其是宿主对感染的反应方式以及将感染推向不同临床结局的因素。鉴于这一重要表现降低了猪的生产能力并加重了全球细胞内劳森氏菌的负担，因此对发病机理的了解将提高事前检验的预测价值，以指导适当的干预措施，包括在疾病的早期阶段对亚临床受影响的猪进行鉴定和治疗。。