Plasmodium malariae is the cause of the rare but severe form of malaria that sometimes affects individuals travelling to malaria-endemic regions. This report presents the unique case of a patient exhibiting severe malaria symptoms caused by P. malariae with no record of recent travel to any malaria-endemic areas. An 81-year-old French woman was admitted to the emergency department with sustained fever and severe weakness for the past 5 days. She suffered from anaemia, thrombocytopenia, confusion, somnolence, pulmonary complications, and hypoxaemia. In the absence of any concrete aetiology that could explain the fever together with thrombocytopenia, physicians suspected malaria as a probable diagnosis. The LAMP-PCR and lateral flow test confirmed the presence of malaria parasite, Plasmodium sp. Microscopic examination (May-Grünwald Giemsa-stained thin blood smear) revealed the presence of trophozoites, schizonts, and gametocytes with 0.93 % parasitaemia. Conventional PCR amplification targeting 510 bp DNA fragment of small subunit ribosomal RNA (ssrRNA) and bidirectional sequencing identified the parasite as Plasmodium malariae. The travel history of this patient revealed her visits to several countries in Europe (Greece), North Africa (Tunisia and Morocco), and the West Indies (Dominican Republic). Of these, the latter was the only country known to be endemic for malaria at the time (three malaria parasite species were prevalent: Plasmodium falciparum, Plasmodium vivax, and P. malariae). The patient had most likely got infected when she visited the Dominican Republic in the summer of 2002. This time interval between the initial parasite infection (2002) till the onset of symptoms and its subsequent diagnosis (2020) is a reminder of the ability of P. malariae to persist in the human host for many years. This report highlights the persistent nature and ability of P. malariae to cause severe infection in the host even after a prolonged time interval.

中文翻译：

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一名法国老年患者由疟疾疟原虫引起的严重长期延迟疟疾

疟疾疟原虫是罕见但严重形式的疟疾的病因，有时会影响前往疟疾流行地区旅行的个人。本报告介绍了一名患者表现出由疟原虫引起的严重疟疾症状的独特案例，该患者最近没有前往任何疟疾流行地区的旅行记录。一名 81 岁的法国妇女在过去 5 天内因持续发烧和严重虚弱被送入急诊室。她患有贫血、血小板减少症、意识模糊、嗜睡、肺部并发症和低氧血症。由于没有任何具体的病因可以解释发热和血小板减少症，医生怀疑疟疾是一种可能的诊断。LAMP-PCR 和侧向流动测试证实了疟原虫疟原虫的存在。显微镜检查（May-Grünwald Giemsa 染色的薄血涂片）显示存在滋养体、裂殖体和配子体，寄生虫血症为 0.93%。针对核糖体小亚基 (ssrRNA) 的 510 bp DNA 片段的常规 PCR 扩增和双向测序将该寄生虫鉴定为疟原虫。该患者的旅行史显示她曾到过欧洲（希腊）、北非（突尼斯和摩洛哥）和西印度群岛（多米尼加共和国）的几个国家。其中，后者是当时已知的唯一疟疾流行国家（三种疟原虫流行：恶性疟原虫、间日疟原虫和疟疾疟原虫）。该患者最有可能在 2002 年夏天访问多米尼加共和国时被感染。从最初的寄生虫感染（2002 年）到症状出现和随后的诊断（2020 年）之间的这段时间间隔提醒我们，疟原虫能够在人类宿主中持续存在多年。该报告强调了疟原虫即使在很长的时间间隔后仍能在宿主中引起严重感染的持久性和能力。