Comparison of detection methods to estimate asexual Plasmodium falciparum parasite prevalence and gametocyte carriage in a community survey in Tanzania
Comparison of detection methods to estimate asexual Plasmodium falciparum parasite prevalence and gametocyte carriage in a community survey in Tanzania
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DOI：
10.1186/1475-2875-13-433
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发表时间：
2014-11-18
期刊：
影响因子：
3
通讯作者：
Felger, Ingrid
中科院分区：
文献类型：
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作者：
Mwingira, Felista;Genton, Blaise;Felger, Ingrid
背景：人们提倡使用分子技术来检测疟疾寄生虫，以提高寄生虫流行率估计的准确性，特别是在中到低流行环境下。分子工作既耗时又昂贵，因此需要仔细评估这项技术的有效收益。在资源有限的地区，通常使用光学显微镜(LM)和快速诊断试验(RDT)来检测疟疾感染，但其敏感性有限，导致低估了感染恶性疟原虫的人数比例。本研究旨在通过坦桑尼亚社区调查来评估漏诊感染的程度，采用聚合酶链式反应检测恶性疟原虫寄生虫和配子体。方法：来自坦桑尼亚基隆贝罗和乌兰加地区的330名所有年龄段的人参加了横断面调查。采集手指抽血，用RDT、LM进行寄生虫检测，用18S rRNA定量聚合酶链式反应(18S RRNA)和msp2nPCR进行分子诊断。用光镜和扩增配子体特异性标记pfs25的转录本检测配子体。结果：所有三种诊断方法的结果都适用于226个个体的亚组。定量聚合酶链式反应检测恶性疟原虫感染率为38%(86/226；95%CI为31.9~44.4%)，RDT法为15.9%(36/226；95%CI为11.1~20.7%)，LM法为5.8%(13/226；95%CI为2.69~8.81%)。RDT阳性标本中有72%(26/36)为qPCR阳性。Pfs25-qRT-PCR检测配子体阳性率为10.6%(24/226)，LM检测配子体阳性率为1.2%。结论：LM检测恶性疟原虫携带者的能力最差，仅检出15%的恶性疟原虫携带者。因此，LM不是一种足够准确的技术，不能用来为政策和疟疾控制或消除工作提供信息。RDT的诊断性能优于LM。然而，当需要准确的流行率数据来监测干预成功或确定全国监测中的点流行率时，这也是不够的。用聚合酶链式反应检测配子体的灵敏度是光镜检查的10倍。这些发现支持需要分子技术来准确估计人类感染性宿主，从而估计人群中的传播潜力。
Background: The use of molecular techniques to detect malaria parasites has been advocated to improve the accuracy of parasite prevalence estimates, especially in moderate to low endemic settings. Molecular work is time-consuming and costly, thus the effective gains of this technique need to be carefully evaluated. Light microscopy (LM) and rapid diagnostic tests (RDT) are commonly used to detect malaria infection in resource constrained areas, but their limited sensitivity results in underestimation of the proportion of people infected with Plasmodium falciparum. This study aimed to evaluate the extent of missed infections via a community survey in Tanzania, using polymerase chain reaction (PCR) to detect P. falciparum parasites and gametocytes.Methods: Three hundred and thirty individuals of all ages from the Kilombero and Ulanga districts (Tanzania) were enrolled in a cross-sectional survey. Finger prick blood samples were collected for parasite detection by RDT, LM and molecular diagnosis using quantitative 18S rRNA PCR and msp2 nPCR. Gametocytes were detected by LM and by amplifying transcripts of the gametocyte-specific marker pfs25.Results: Results from all three diagnostic methods were available for a subset of 226 individuals. Prevalence of P. falciparum was 38% (86/226; 95% CI 31.9-44.4%) by qPCR, 15.9% (36/226; 95% CI 11.1-20.7%) by RDT and 5.8% (13/226; 95% CI 2.69-8.81%) by LM. qPCR was positive for 72% (26/36) of the RDT-positive samples. Gametocyte prevalence was 10.6% (24/226) by pfs25-qRT-PCR and 1.2% by LM.Conclusions: LM showed the poorest performance, detecting only 15% of P. falciparum parasite carriers identified by PCR. Thus, LM is not a sufficiently accurate technique from which to inform policies and malaria control or elimination efforts. The diagnostic performance of RDT was superior to that of LM. However, it is also insufficient when precise prevalence data are needed for monitoring intervention success or for determining point prevalence rates in countrywide surveillance. Detection of gametocytes by PCR was 10-times more sensitive than by LM. These findings support the need for molecular techniques to accurately estimate the human infectious reservoir and hence the transmission potential in a population.