Cuadros Juan, Martin Ramírez Alexandra, González Iveth J, Ding Xavier C, Perez Tanoira Ramon, Rojo-Marcos Gerardo, Gómez-Herruz Peña, Rubio Jose Miguel
Department of Clinical Microbiology and Parasitology, Hospital Príncipe de Asturias, 28805, Alcalá de Henares, Madrid, Spain.
Department of Clinical Microbiology and Parasitology, Hospital de la Princesa, Madrid, Spain.
Malar J. 2017 Jan 7;16(1):20. doi: 10.1186/s12936-016-1669-8.
Microscopy and rapid diagnosis tests have a limited sensitivity in diagnosis of malaria by Plasmodium ovale. The LAMP kit (LoopAMP®) can be used in the field without special equipment and could have an important role in malaria control programmes in endemic areas and for malaria diagnosis in returned travellers. The performance of the Pan primer of the kit in detecting malaria by P. ovale was compared with the results of standard nPCR in samples of patients returning from P. ovale endemic areas.
Plasmodium ovale positive samples (29, tested by PCR and/or microscopy) and malaria negative specimens (398, tested by microscopy and PCR) were collected in different hospitals of Europe from June 2014 to March 2016 and frozen at -20 °C. Boil and spin method was used to extract DNA from all samples and amplification was performed with LoopAMP® MALARIA kit (Eiken Chemical, Japan) in an automated turbidimeter (Eiken 500). The results of LAMP read by turbidimetry and with the naked eye were compared.
The kit showed a sensitivity of 100% and a specificity of 97.24% with positive and negative predictive values of 72.5 and 100%, respectively. Naked eyed readings were in accordance with turbidimetry readings (sensitivity, 92.5%, specificity, 98.96% and positive and negative predictive values, respectively, 90.24 and 99.22%). The limit of detection of LAMP assay for P. ovale was between 0.8 and 2 parasites/µl.
The Pan primer of the Malaria kit LoopAMP® can detect P. ovale at very low-levels and showed a predictive negative value of 100%. This tool can be useful in malaria control and elimination programmes and in returned travellers from P. ovale endemic areas. Naked eye readings are equivalent to automated turbidimeter readings in specimens obtained with EDTA.
显微镜检查和快速诊断测试在卵形疟原虫疟疾诊断中的敏感性有限。环介导等温扩增试剂盒（LoopAMP®）无需特殊设备即可在现场使用，在疟疾流行地区的疟疾控制计划以及归国旅行者的疟疾诊断中可能发挥重要作用。将该试剂盒的泛引物检测卵形疟原虫疟疾的性能与来自卵形疟原虫流行地区的归国患者样本中标准巢式PCR的结果进行了比较。
2014年6月至2016年3月期间，在欧洲不同医院收集了经PCR和/或显微镜检查的卵形疟原虫阳性样本（29份）和疟疾阴性标本（398份，经显微镜检查和PCR检测），并在-20°C下冷冻。采用煮沸离心法从所有样本中提取DNA，并使用环介导等温扩增疟疾试剂盒（LoopAMP®，日本荣化学株式会社）在自动浊度仪（荣化学500）中进行扩增。比较了通过浊度法和肉眼读取的环介导等温扩增结果。
该试剂盒的敏感性为100%，特异性为97.24%，阳性预测值和阴性预测值分别为72.5和100%。肉眼读数与浊度法读数一致（敏感性为92.5%，特异性为98.96%，阳性预测值和阴性预测值分别为90.24和99.22%）。环介导等温扩增法检测卵形疟原虫的检测限为0.8至2个寄生虫/微升。
疟疾试剂盒环介导等温扩增试剂盒（LoopAMP®）的泛引物能够在极低水平下检测到卵形疟原虫，其阴性预测值为100%。该工具可用于疟疾控制和消除计划以及来自卵形疟原虫流行地区的归国旅行者。在用乙二胺四乙酸（EDTA）获得的标本中，肉眼读数等同于自动浊度仪读数。
