Africa University, Mutare, Zimbabwe.
National Institute of Health Research, Harare, Zimbabwe.
Malar J. 2021 Jan 6;20(1):14. doi: 10.1186/s12936-020-03536-7.
Microscopy and rapid diagnostic tests (RDTs) are the main techniques used to diagnose malaria. While microscopy is considered the gold standard, RDTs have established popularity as they allow for rapid diagnosis with minimal technical skills. This study aimed to compare the diagnostic performance of two Plasmodium falciparum histidine-rich protein 2 (PfHRP2)-based RDTs (Paracheck Pf® Test (Paracheck) and Malaria Pf™ ICT (ICT)) to polymerase chain reaction (PCR) in a community survey.
A cross-sectional study was conducted between October 2012 and December 2014 in Mutasa District, Manicaland Province, eastern Zimbabwe. Households were randomly selected using satellite imagery, and 224 households were visited. Residents present in the household on the date of the visit were recruited for the study. Participants of all age groups from the selected households were screened with Paracheck and ICT RDTs in parallel. Dried blood spots (DBS) and thin and thick smears were collected. Parasite DNA extracted from the DBS was subjected to nested PCR targeting the Plasmodium cytochrome b mitochondrial gene. Data analysis was performed using the Cohen's Kappa test to determine the interrater agreement and the sensitivity and specificity of the diagnostic test were reported.
Results from a total of 702 participants were analysed. Most were females, 397 (57%), and the median age of participants was 21 years with an interquartile range of 9-39 years. Of those who were screened, 8 (1.1%), 35 (5.0%), and 21 (2.9%) were malaria parasite positive by microscopy, RDT and PCR, respectively. Paracheck and ICT RDTs had a 100% agreement. Comparing RDT and PCR results, 34 participants (4.8%) had discordant results. Most of the discordant cases were RDT positive but PCR negative (n = 24). Half of those RDT positive, but PCR negative individuals reported anti-malarials to use in the past month, which is significantly higher than reported anti-malarial drug use in the population (p < 0.001). The participant was febrile on the day of the visit, but relying on PfHRP2-based RDT would miss this case. Among the diagnostic methods evaluated, with reference to PCR, the sensitivity was higher with the RDT (52.4%) while specificity was higher with the microscopy (99.9%). The positive predictive value (PPV) was higher with the microscopy (87.5%), while the negative predictive values were similar for both microscopy and RDTs (98%). Overall, a strong correlated agreement with PCR was observed for the microscopy (97.9%) and the RDTs (95.2%).
Paracheck and ICT RDTs showed 100% agreement and can be used interchangeably. As malaria transmission declines and Zimbabwe aims to reach malaria elimination, management of infected individuals with low parasitaemia as well as non-P. falciparum infection can be critical.
显微镜检查和快速诊断检测（RDT）是诊断疟疾的主要技术。虽然显微镜检查被认为是金标准，但 RDT 因其允许在最少的技术技能下进行快速诊断而广受欢迎。本研究旨在比较两种基于恶性疟原虫环子氨酸蛋白 2（PfHRP2）的 RDT（Paracheck Pf®Test（Paracheck）和 Malaria Pf™ICT（ICT））与聚合酶链反应（PCR）在社区调查中的诊断性能。
2012 年 10 月至 2014 年 12 月，在津巴布韦马尼卡兰省马塔萨区进行了一项横断面研究。使用卫星图像随机选择家庭，共访问了 224 个家庭。在访问日在家中的居民被招募参加研究。从选定家庭中所有年龄组的参与者都同时使用 Paracheck 和 ICT RDT 进行筛查。收集干燥血斑（DBS）和薄血涂片和厚血涂片。从 DBS 中提取寄生虫 DNA，进行巢式 PCR 检测疟原虫细胞色素 b 线粒体基因。使用 Cohen's Kappa 检验进行数据分析，以确定评价者间的一致性，并报告诊断试验的敏感性和特异性。
对共 702 名参与者的结果进行了分析。大多数是女性，占 397 名（57%），参与者的中位数年龄为 21 岁，四分位距为 9-39 岁。通过显微镜检查、RDT 和 PCR 检测，分别有 8 名（1.1%）、35 名（5.0%）和 21 名（2.9%）疟原虫阳性。Paracheck 和 ICT RDT 具有 100%的一致性。比较 RDT 和 PCR 结果，有 34 名（4.8%）参与者的结果不一致。大多数不一致的病例是 RDT 阳性但 PCR 阴性（n=24）。一半的 RDT 阳性但 PCR 阴性个体报告过去一个月使用过抗疟药，这明显高于人群中报告的抗疟药使用情况（p<0.001）。在就诊当天，患者发热，但仅凭 PfHRP2 为基础的 RDT 可能会漏诊。在所评估的诊断方法中，参照 PCR，RDT 的敏感性更高（52.4%），而显微镜检查的特异性更高（99.9%）。显微镜检查的阳性预测值（PPV）更高（87.5%），而显微镜检查和 RDT 的阴性预测值相似（98%）。总体而言，与 PCR 相比，显微镜检查（97.9%）和 RDT（95.2%）均具有很强的相关一致性。
Paracheck 和 ICT RDT 显示出 100%的一致性，可以相互替换使用。随着疟疾传播的减少，津巴布韦旨在实现消除疟疾的目标，管理低疟原虫血症的感染个体以及非恶性疟原虫感染可能至关重要。
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