Department of Basic Sciences, Faculty of Medicine, University of Kinshasa, Kinshasa, Democratic Republic of Congo.
School of Public Health, Faculty of Medicine, University of Kinshasa, Kinshasa, Democratic Republic of Congo.
Malar J. 2020 Mar 20;19(1):121. doi: 10.1186/s12936-020-03192-x.
The loss of chloroquine (CQ) effectiveness has led to its withdrawal from national policies as a first-line treatment for uncomplicated malaria in several endemic countries, such as the Democratic Republic of Congo (DRC). The K76T mutation on the pfcrt gene has been identified as a marker of CQ resistance and the SVMNT haplotype in codons 72-76 on the same gene has been associated with resistance to amodiaquine (AQ). In the DRC, the prevalence of K76T has decreased from 100% in 2000 to 63.9% in 2014. The purpose of this study was to determine the prevalence of K76T mutations in circulating strains of Plasmodium falciparum, 16 years after CQ withdrawal in the DRC and to investigate the presence of the SVMNT haplotype.
In 2017, ten geographical sites across the DRC were selected. Dried blood samples were collected from patients attending health centres. Malaria was first detected by a rapid diagnostic test (RDT) available on site (SD Bioline Malaria Ag Pf or CareStart Malaria Pf) or thick blood smear and then confirmed by a P. falciparum species-specific real-time PCR assay. A pfcrt gene segment containing a fragment that encodes amino acids at positions 72-76 was amplified by conventional PCR before sequencing.
A total of 1070 patients were enrolled. Of the 806 PCR-confirmed P. falciparum positive samples, 764 were successfully sequenced. The K76T mutation was detected in 218 samples (28.5%; 95% CI 25.4%-31.9%), mainly (96%) with the CVIET haplotype. Prevalence of CQ resistance marker was unequally distributed across the country, ranging from 1.5% in Fungurume to 89.5% in Katana. The SVMNT haplotype, related to AQ resistance, was not detected.
Overall, the frequency of the P. falciparum CQ resistance marker has decreased significantly and no resistance marker to AQ was detected in the DRC in 2017. However, the between regions variability of CQ resistance remains high in the country. Further studies are needed for continuous monitoring of the CQ resistance level for its prospective re-use in malaria management. The absence of the AQ resistance marker is in line with the use of this drug in the current DRC malaria treatment policy.
氯喹（CQ）疗效的丧失已导致其在一些流行国家（例如刚果民主共和国）从国家政策中撤出，作为治疗无并发症疟疾的一线药物。pfcrt 基因上的 K76T 突变已被确定为 CQ 耐药的标志物，而同一基因上的 72-76 密码子中的 SVMNT 单倍型与对阿莫地喹（AQ）的耐药性有关。在刚果民主共和国，K76T 的流行率已从 2000 年的 100％下降到 2014 年的 63.9％。本研究的目的是在刚果民主共和国停止使用 CQ 16 年后，确定循环疟原虫虫株中 K76T 突变的流行率，并调查 SVMNT 单倍型的存在。
2017 年，在刚果民主共和国选择了十个地理地点。从在卫生中心就诊的患者中采集干燥的血样。首先通过现场可用的快速诊断测试（RDT）（SD Bioline 疟疾 Ag Pf 或 CareStart 疟疾 Pf）或厚血涂片检测疟疾，然后通过 P. falciparum 种特异性实时 PCR 检测进行确认。通过常规 PCR 扩增包含编码位置 72-76 处氨基酸的片段的 pfcrt 基因片段，然后进行测序。
共纳入了 1070 名患者。在 806 例经 PCR 确认的 P. falciparum 阳性样本中，有 764 例成功测序。在 218 例（28.5％；95％CI 25.4％-31.9％）中检测到 K76T 突变，主要（96％）为 CVIET 单倍型。CQ 耐药标志物的流行率在全国范围内分布不均，从 Fungurume 的 1.5％到 Katana 的 89.5％不等。与 AQ 耐药性相关的 SVMNT 单倍型未被检出。
总体而言，2017 年在刚果民主共和国，疟原虫 CQ 耐药标志物的频率已显着降低，并且未检测到对 AQ 的耐药标志物。然而，该国 CQ 耐药性的区域间变异性仍然很高。需要进一步研究来持续监测 CQ 耐药水平，以将其重新用于疟疾管理。缺乏 AQ 耐药标志物与当前刚果民主共和国疟疾治疗政策中使用该药物相符。
