Department of Tropical Medicine and Malaria, Research Institute, National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo, 162-8655, Japan.
Disease Control and Prevention Center of National Center for Global Health and Medicine, 1-21-1 Toyama, Shinjuku-ku, Tokyo, 162-8655, Japan.
Malar J. 2022 Jul 30;21(1):229. doi: 10.1186/s12936-022-04247-x.
The automated haematology analyzer XN-31 prototype (XN-31p) is a new flow cytometry-based device developed to measure the number and the ratio of malaria-infected red blood cells (MI-RBC) with a complete blood count (CBC). The XN-31p can provide results in about one minute and also can simultaneously provide information on the malaria parasite (Plasmodium) species. In this study, clinical testing of the XN-31p was performed using blood samples from patients with imported malaria in Japan.
Blood samples were collected from 80 patients who visited the hospital of the National Center for Global Health and Medicine, Tokyo, Japan, for malaria diagnosis from January 2017 to January 2019. The test results by the XN-31p were compared with those by other standard methods, such as microscopic observation, rapid diagnostic tests and the nested PCR.
Thirty-three patients were diagnosed by the nested PCR as being malaria positive (28 Plasmodium falciparum, 2 Plasmodium vivax, 1 Plasmodium knowlesi, 1 mixed infection of P. falciparum and Plasmodium malariae, and 1 mixed infection of P. falciparum and Plasmodium ovale), and the other 47 were negative. The XN-31p detected 32 patients as "MI-RBC positive", which almost matched the results by the nested PCR and, in fact, completely matched with the microscopic observations. The ratio of RBCs infected with malaria parasites as determined by the XN-31p showed a high correlation coefficient of more than 0.99 with the parasitaemia counted under microscopic observation. The XN-31p can analyse the size and nucleic acid contents of each cell, and the results were visualized on a two-dimensional cytogram termed the "M scattergram". Information on species and developmental stages of the parasites could also be predicted from the patterns visualized in the M scattergrams. The XN-31p showed a positive coincidence rate of 0.848 with the nested PCR in discriminating P. falciparum from the other species.
The XN-31p could rapidly provide instructive information on the ratio of MI-RBC and the infecting Plasmodium species. It was regarded to be of great help for the clinical diagnosis of malaria.
XN-31 原型自动化血液分析仪（XN-31p）是一种新的基于流式细胞术的设备，旨在通过全血细胞计数（CBC）测量疟原虫感染的红细胞（MI-RBC）的数量和比例。XN-31p 大约可以在一分钟内提供结果，并且还可以同时提供关于疟原虫（疟原虫）种类的信息。在这项研究中，使用来自日本输入性疟疾患者的血液样本对 XN-31p 进行了临床测试。
从 2017 年 1 月至 2019 年 1 月，在日本国立全球卫生与医学中心医院就诊的 80 名疟疾诊断患者采集了血液样本。将 XN-31p 的检测结果与其他标准方法（例如显微镜观察、快速诊断测试和巢式 PCR）进行了比较。
33 名患者通过巢式 PCR 诊断为疟疾阳性（28 例恶性疟原虫，2 例间日疟原虫，1 例疟原虫 knowlesi，1 例恶性疟原虫和疟原虫间日疟原虫混合感染，1 例恶性疟原虫和疟原虫卵形混合感染），而另外 47 名患者为阴性。XN-31p 检测到 32 名“MI-RBC 阳性”患者，几乎与巢式 PCR 的结果相符，实际上与显微镜观察完全相符。XN-31p 检测到的疟原虫感染 RBC 的比例与显微镜下计数的寄生虫血症之间具有大于 0.99 的高相关系数。XN-31p 可以分析每个细胞的大小和核酸含量，并在称为“M 散射图”的二维细胞图上可视化结果。还可以从 M 散射图中可视化的模式预测寄生虫的种类和发育阶段。XN-31p 在区分恶性疟原虫和其他物种方面与巢式 PCR 的阳性符合率为 0.848。
XN-31p 可以快速提供有关 MI-RBC 比例和感染疟原虫种类的指导信息。它被认为对疟疾的临床诊断有很大帮助。
