Centre for International Health, Faculty of Medicine, University of Bergen, Bergen, Norway.
Department of Biomedical Science, School of Health Sciences, University of Zambia, Lusaka, Zambia.
Malar J. 2019 Apr 11;18(1):130. doi: 10.1186/s12936-019-2766-2.
Zambia continues to make strides in reducing malaria burden through the use of proven malaria interventions and has recently pledged to eliminate malaria by 2021. Case management services have been scaled up at community level with rapid diagnostic tests (RDTs) providing antigen-based detection of falciparum malaria only. Key to national malaria elimination goals is the ability to identify, treat and eliminate all Plasmodium species. This study sought to determine the distribution of non-falciparum malaria and assess the performance of diagnostic tests for Plasmodium falciparum in Western and Southern Provinces of Zambia, two provinces planned for early malaria elimination.
A sub-set of individuals' data and samples from a cross-sectional household survey, conducted during peak malaria transmission season in April and May 2017, was used. The survey collected socio-demographic information on household members and coverage of malaria interventions. Malaria testing was done on respondents of all ages using blood smears and RDTs while dried blood spots were collected on filter papers for analysis using photo-induced electron transfer polymerase chain reaction (PET-PCR). Slides were stained using Giemsa stain and examined by microscopy for malaria parasites.
From the 1567 individuals included, the overall prevalence of malaria was 19.4% (CI 17.5-21.4) by PCR, 19.3% (CI 17.4-21.4) by RDT and 12.9% (CI 11.3-14.7) by microscopy. Using PET-PCR as the gold standard, RDTs showed a sensitivity of 75.7% (CI 70.4-80.4) and specificity of 94.2% (CI 92.8-95.4). The positive predictive value (PPV) was 75.9% (CI 70.7-80.6) and negative predictive value (NPV) was 94.1% (CI 92.1-95.4). In contrast, microscopy for sensitivity, specificity, PPV, and NPV values were 56.9% (CI 51.1-62.5), 97.7% (CI 96.7-98.5), 85.6% (CI 80.0-90.2), 90.4% (CI 88.7-91.9), respectively. Non-falciparum infections were found only in Western Province, where 11.6% of P. falciparum infections were co-infections with Plasmodium ovale or Plasmodium malariae.
From the sub-set of survey data analysed, non-falciparum species are present and occurred as mixed infections. As expected, PET-PCR was slightly more sensitive than both malaria RDTs and microscopy to detecting malaria infections.
赞比亚通过使用经证实的疟疾干预措施，在降低疟疾负担方面继续取得进展，最近承诺到 2021 年消除疟疾。在社区层面扩大了病例管理服务，快速诊断检测（RDT）仅提供基于抗原的恶性疟原虫检测。国家消除疟疾目标的关键是能够识别、治疗和消除所有疟原虫。本研究旨在确定非恶性疟原虫疟疾的分布，并评估诊断检测在赞比亚西部和南部省份的表现，这两个省份计划提前消除疟疾。
使用了横断面家庭调查中部分个人的数据和样本，该调查于 2017 年 4 月和 5 月疟疾传播高峰期进行。该调查收集了有关家庭成员工资的社会人口学信息以及疟疾干预措施的覆盖情况。对所有年龄的受访者使用血涂片和 RDT 进行疟疾检测，同时在滤纸上收集干血斑，以便使用光诱导电子转移聚合酶链反应（PET-PCR）进行分析。载玻片用吉姆萨染色，然后用显微镜检查疟原虫。
在纳入的 1567 名个体中，PCR 检测的疟疾总患病率为 19.4%（95%CI 17.5-21.4），RDT 检测的疟疾总患病率为 19.3%（95%CI 17.4-21.4），显微镜检测的疟疾总患病率为 12.9%（95%CI 11.3-14.7）。以 PET-PCR 为金标准，RDT 的灵敏度为 75.7%（95%CI 70.4-80.4），特异性为 94.2%（95%CI 92.8-95.4）。阳性预测值（PPV）为 75.9%（95%CI 70.7-80.6），阴性预测值（NPV）为 94.1%（95%CI 92.1-95.4）。相比之下，显微镜的灵敏度、特异性、PPV 和 NPV 值分别为 56.9%（95%CI 51.1-62.5）、97.7%（95%CI 96.7-98.5）、85.6%（95%CI 80.0-90.2）和 90.4%（95%CI 88.7-91.9）。仅在西部省发现了非恶性疟原虫感染，其中 11.6%的恶性疟原虫感染是与卵形疟原虫或间日疟原虫的混合感染。
从分析的调查数据子集中可以看出，存在非恶性疟原虫，并且发生了混合感染。如预期的那样，PET-PCR 检测疟疾感染的敏感性略高于疟疾 RDT 和显微镜。
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