Department of Microbiology and Parasitology, University of Queensland, Mount Mellum, Queensland, Australia.
Sullivan Nicolaides Pathology, Brisbane, Brisbane, Queensland, Australia.
Am J Trop Med Hyg. 2018 Feb;98(2):353-359. doi: 10.4269/ajtmh.17-0206. Epub 2017 Nov 30.
Infection with the Rat Lungworm is the leading cause of human eosinophilic meningoencephalitis worldwide. From its origins in southeastern Asia, the parasite was spread extensively throughout the twentieth century and is now established in many of the world's warmer regions. Its clinical effects range from mild and transient symptoms, usually headache with peripheral nerve dysfunction, to severe and permanent central nervous system (CNS) damage, occasionally fatal. The severity and prognosis of disease are determined by the larval dose, acquired by ingesting infected intermediate hosts (slugs and snails) or, less often, paratenic hosts, such as crabs, shrimps, frogs, and monitor lizards. Early diagnosis is critical for treatment and depends on clinical suspicion, for laboratory confirmation from blood and cerebrospinal fluid can be delayed and unreliable. Treatment is fraught with difficulty, compounded by conflicting published results. Corticosteroids play a useful role in suppressing early CNS inflammation, but their duration for maintenance becomes problematic in severe infections. Because most of the pathogenesis results from host immuno-inflammatory responses to migrating and dead larvae in the CNS, anthelminthic therapy remains controversial: if effective, it kills viable larvae, arresting them in the CNS and so exacerbating the pathology. In human infections, it is now clear that many larvae do leave the CNS and reach the pulmonary arteries, sometimes with clinical consequences. Pioneering life-cycle studies in rats demonstrated a "subarachnoid phase" in larval development and migration; recent autopsy findings, outlined here, show it also occurs in humans and has some bearing on treatment. One new and four previously reported cases of human infection are analyzed here, with findings indicating that anthelminthic treatment is effective only when given early and should not be commenced beyond 3 weeks after exposure to infection. In endemic areas, treatment should start as soon as this infection is suspected, even without a clear history of exposure, given the unacceptable risks of waiting for diagnostic laboratory confirmation.
感染鼠肺并殖吸虫是全世界人类嗜酸性粒细胞性脑膜脑炎的主要原因。这种寄生虫起源于东南亚，在 20 世纪广泛传播，现在已在世界上许多温暖地区扎根。其临床影响范围从轻度和短暂的症状（通常为头痛伴周围神经功能障碍）到严重和永久性的中枢神经系统（CNS）损伤，偶尔致命。疾病的严重程度和预后取决于幼虫剂量，这是通过摄入受感染的中间宿主（鼻涕虫和蜗牛）或不太常见的副宿主（如螃蟹、虾、青蛙和巨蜥）获得的。早期诊断对治疗至关重要，这取决于临床怀疑，因为从血液和脑脊液中进行实验室确认可能会延迟且不可靠。治疗困难重重，并且由于发表的结果相互矛盾，情况更加复杂。皮质类固醇在抑制早期 CNS 炎症方面发挥了有用的作用，但在严重感染中，其维持时间会出现问题。由于大多数发病机制是由于宿主对 CNS 中迁移和死亡幼虫的免疫炎症反应引起的，因此驱虫治疗仍然存在争议：如果有效，它会杀死有活力的幼虫，使它们在 CNS 中停滞不前，从而加剧病理学。在人类感染中，现在很清楚，许多幼虫确实离开 CNS 并到达肺动脉，有时会产生临床后果。在大鼠中进行的开创性生命周期研究表明，幼虫发育和迁移存在“蛛网膜下腔阶段”；这里概述的最近尸检结果表明，该阶段也发生在人类中，并对治疗有一定影响。这里分析了一例新的和四例以前报告的人类感染病例，结果表明，只有在早期给予驱虫治疗才有效，并且不应在感染暴露后超过 3 周开始治疗。在流行地区，即使没有明确的暴露史，只要怀疑感染，就应开始治疗，因为等待诊断实验室确认的风险不可接受。
