Department of Biochemistry and Molecular Biology, University of Buea, Buea, Cameroon.
Department of Chemical and Biological Engineering, National Higher Polytechnic Institute, The University of Bamenda, Bamenda, Cameroon.
Infect Dis Poverty. 2021 May 22;10(1):75. doi: 10.1186/s40249-021-00859-8.
Malaria remains a significant health challenge in sub-Saharan Africa, with early diagnosis critical to reducing its morbidity and mortality. Despite the increasing Plasmodium spp. diagnostic capabilities, access to testing is limited in some cases by the almost absolute requirement for blood from potentially infected subjects as the only sample source for all conventional methods. A rapid test on non-invasive specimen with comparable performance to microscopy for the screening or diagnosis of all participants is invaluable. This study sought to compare conventional and non-invasive diagnostic tools for detecting Plasmodium falciparum.
This was a cross-sectional study, carried out between March and August 2019 to evaluate and compare the diagnostic performance of a PfHRP2/pLDH-based malaria rapid diagnostic test (mRDT) on patients' blood, saliva and urine relative to conventional light microscopy and nested PCR at outpatient clinics in the Buea and Tiko health districts of Southwestern Cameroon. The significance of differences in proportions was explored using the Pearson's χ test whereas differences in group means were assessed using analyses of variance.
A total of 359 individuals of both sexes, aged 1-92 years, were enrolled into the study. Of the 301 individuals tested by light microscopy and mRDTs on blood, saliva and urine, 84 (27.9%), 81 (26.9%), 87 (28.9%) and 107 (35.5%) respectively were positive. However, only 34.3%, 90.5%, 91.4%, 83.9% and 65.4% febrile, light microscopy and mRDT positives on blood, saliva and urine respectively had P. falciparum infection as confirmed by PCR. The sensitivity and specificity of presumptive diagnosis, light microscopy and mRDT on blood, saliva and urine were 86.9% and 19.7%, 77.8% and 96.1%, 75.8% and 96.6%, 74.5% and 93.1%, and 70.7% and 81.8%, respectively. The agreement between mRDT on saliva (k = 0.696) and microscopy (k = 0.766) compared to PCR was good.
The study highlighted the low performance of presumptive diagnosis, reinforcing the need for parasitological tests prior to antimalarial therapy. The higher PfHRP2/pLDH mRDT parasite detection rates and sensitivity in saliva compared to urine suggests that the former is a practical adjunct to or alternative worth optimising for the routine diagnosis of malaria. Flow chart for diagnosis of P. falciparum infection by light microscopy, rapid diagnostic tests and nested PCR.
疟疾仍然是撒哈拉以南非洲地区的一个重大健康挑战，早期诊断对于降低其发病率和死亡率至关重要。尽管疟原虫 spp. 的诊断能力有所提高，但在某些情况下，由于所有常规方法都几乎绝对需要从潜在感染的受试者身上获取血液作为唯一的样本来源，因此检测的可及性受到限制。对于所有参与者进行筛查或诊断的非侵入性样本的快速检测与显微镜检查具有相当的性能是非常宝贵的。本研究旨在比较传统和非侵入性诊断工具在检测恶性疟原虫中的作用。
这是一项横断面研究，于 2019 年 3 月至 8 月在喀麦隆西南部的布埃和蒂科卫生区的门诊诊所进行，评估和比较基于 PfHRP2/pLDH 的疟疾快速诊断检测（mRDT）在患者血液、唾液和尿液中的检测性能与传统的显微镜检查和巢式 PCR。使用 Pearson χ 检验探索比例差异的显著性，而组间均值的差异则使用方差分析进行评估。
共纳入 359 名男女患者，年龄 1-92 岁。在接受显微镜检查和 mRDT 检测的 301 名血液、唾液和尿液样本中，分别有 84（27.9%）、81（26.9%）、87（28.9%）和 107（35.5%）呈阳性。然而，只有 34.3%、90.5%、91.4%、83.9%和 65.4%的发热、显微镜检查和 mRDT 阳性的血液、唾液和尿液样本的疟原虫感染得到 PCR 证实。血液、唾液和尿液中 mRDT 的敏感性和特异性分别为 86.9%和 19.7%、77.8%和 96.1%、75.8%和 96.6%、74.5%和 93.1%、70.7%和 81.8%。唾液 mRDT（k=0.696）与显微镜检查（k=0.766）与 PCR 的一致性较好。
该研究强调了初步诊断的低性能，这强化了在进行抗疟治疗前进行寄生虫学检查的必要性。与尿液相比，唾液中 PfHRP2/pLDH mRDT 的寄生虫检测率和敏感性更高，这表明前者是优化常规疟疾诊断的实用辅助手段或值得优化的替代手段。
