Adamu Aderaw, Alemu Getaneh, Yimer Mulat, Tegegne Banchamlak, Mekasha Sindew
Department of Medical Laboratory Science, Wollo University, Dessie, Ethiopia.
Department of Medical Laboratory Science, College of Medicine and Health Sciences, Bahir Dar University, P.O. Box 79, Bahir Dar, Ethiopia.
Malar J. 2025 Aug 2;24(1):250. doi: 10.1186/s12936-025-05485-5.
Plasmodium falciparum histidine-rich protein 2 (pfhrp2)-based rapid diagnostic tests (RDTs) have been instrumental in enhancing malaria surveillance and case management, especially in Africa where P. falciparum predominates. However, the emergence of pfhrp2/3 gene deletions poses a serious threat to their effectiveness. Therefore, regular monitoring of pfhrp2/3 deletion status at both local and national levels is essential to inform policy decisions on appropriate diagnostic strategies.
A health facility-based cross-sectional study was conducted from January 2021 to 2022 across 28 health facilities in three survey domains (Gondar, Gojjam, and East Amhara) within the Amhara region of Ethiopia. The study included 1232 microscopy-confirmed P. falciparum patients. Participants were recruited through convenient sampling based on informed consent. Socio-demographic and clinical data were collected using a structured questionnaire. Capillary blood samples were obtained and tested for Plasmodium infection using pfhrp2-based RDTs, microscopy, and polymerase chain reaction (PCR). PCR analysis specifically targeted the pfhrp2 and pfhrp3 genes to detect deletions. Descriptive statistics were performed using SPSS version 20.0 to summarize participant characteristics and calculate the prevalence of gene deletions.
Among 1232 microscopy-confirmed P. falciparum-positive samples, 123 were suspected of pfhrp2/3 gene deletion (i.e., microscopy positive but RDT negative). These 123 discordant samples and 87 samples with concordant RDT and microscopy-positive results (total 210) were recruited for the pfhrp2/3 gene deletion study using PCR. An additional 17 concordant and 14 discordant samples (a total of 31) were excluded due to insufficient DNA amplification. As a result, pfhrp2/3 gene deletion analysis was conducted on 179 samples. Of these, 158 (88.3%) samples had either one or both of the pfhrp2 and pfhrp3 gene deletions. Ninety-two (51.4%), 4 (2.2%) and 62 (34.6%) samples were with dual pfhrp2/3, Pfhrp2 and pfhrp3 gene deletions, respectively. Among 109 false-negative pfhrp2/3 RDT results, 102 (93.6%) were due to pfhrp2/3 gene deletions. P. falciparum with pfhrp2 and pfhrp3 or dual gene deletion was found in all survey domains.
The regional prevalence of pfhrp2/3 gene deletion is above the threshold (5%) recommended by the World Health Organization. Plasmodium falciparum strains with pfhrp2/3 gene deletion are distributed throughout the Amhara region. Continued use of the newly introduced LDH-based Biocredit RDTs is recommended in Ethiopia.
基于恶性疟原虫富含组氨酸蛋白2（pfhrp2）的快速诊断检测（RDT）在加强疟疾监测和病例管理方面发挥了重要作用，特别是在恶性疟原虫占主导的非洲地区。然而，pfhrp2/3基因缺失的出现对其有效性构成了严重威胁。因此，在地方和国家层面定期监测pfhrp2/3缺失状况对于为适当诊断策略的政策决策提供依据至关重要。
2021年1月至2022年，在埃塞俄比亚阿姆哈拉地区的三个调查区域（贡德尔、戈贾姆和东阿姆哈拉）的28个医疗机构开展了一项基于医疗机构的横断面研究。该研究纳入了1232例经显微镜检查确诊的恶性疟原虫患者。参与者通过基于知情同意的便利抽样招募。使用结构化问卷收集社会人口学和临床数据。采集毛细血管血样，使用基于pfhrp2的RDT、显微镜检查和聚合酶链反应（PCR）检测疟原虫感染。PCR分析专门针对pfhrp2和pfhrp3基因以检测缺失。使用SPSS 20.0版进行描述性统计，以总结参与者特征并计算基因缺失的患病率。
在1232例经显微镜检查确诊的恶性疟原虫阳性样本中，123例怀疑存在pfhrp2/3基因缺失（即显微镜检查阳性但RDT阴性）。这123例不一致样本和87例RDT与显微镜检查结果一致为阳性的样本（共210例）被纳入使用PCR的pfhrp2/3基因缺失研究。另外17例一致样本和14例不一致样本（共31例）因DNA扩增不足而被排除。结果，对179例样本进行了pfhrp2/3基因缺失分析。其中，158例（占比88.3%）样本存在pfhrp2和pfhrp3基因中的一个或两个基因缺失。分别有92例（占比51.4%）、4例（占比2.2%）和62例（占比34.6%）样本存在pfhrp2/3双基因、Pfhrp2和pfhrp3基因缺失。在109例假阴性pfhrp2/3 RDT结果中，102例（占比93.6%）是由于pfhrp2/3基因缺失。在所有调查区域均发现了具有pfhrp2和pfhrp3或双基因缺失的恶性疟原虫。
pfhrp2/3基因缺失的区域患病率高于世界卫生组织推荐的阈值（5%）。具有pfhrp2/3基因缺失的恶性疟原虫菌株分布于整个阿姆哈拉地区。建议在埃塞俄比亚继续使用新引入的基于乳酸脱氢酶的Biocredit RDT。
