Mekonnen Seleshi Kebede, Aseffa Abraham, Berhe Nega, Teklehaymanot Tilahun, Clouse Ronald M, Gebru Tamirat, Medhin Girmay, Velavan Thirumalaisamy P
Aklilu Lemma Institute of Pathobiology, Addis Ababa University, Addis Ababa, Ethiopia.
Malar J. 2014 Jun 25;13:244. doi: 10.1186/1475-2875-13-244.
Increased resistance by Plasmodium falciparum parasites led to the withdrawal of the antimalarial drugs chloroquine and sulphadoxine-pyrimethamine in Ethiopia. Since 2004 artemether-lumefantrine has served to treat uncomplicated P. falciparum malaria. However, increasing reports on delayed parasite clearance to artemisinin opens up a new challenge in anti-malarial therapy. With the complete withdrawal of CQ for the treatment of Plasmodium falciparum malaria, this study assessed the evolution of CQ resistance by investigating the prevalence of mutant alleles in the pfmdr1 and pfcrt genes in P. falciparum and pvmdr1 gene in Plasmodium vivax in Southern and Eastern Ethiopia.
Of the 1,416 febrile patients attending primary health facilities in Southern Ethiopia, 329 febrile patients positive for P. falciparum or P. vivax were recruited. Similarly of the 1,304 febrile patients from Eastern Ethiopia, 81 febrile patients positive for P. falciparum or P. vivax were included in the study. Of the 410 finger prick blood samples collected from malaria patients, we used direct sequencing to investigate the prevalence of mutations in pfcrt and pfmdr1. This included determining the gene copy number in pfmdr1 in 195 P. falciparum clinical isolates, and mutations in the pvmdr1 locus in 215 P. vivax clinical isolates.
The pfcrt K76 CQ-sensitive allele was observed in 84.1% of the investigated P.falciparum clinical isolates. The pfcrt double mutations (K76T and C72S) were observed less than 3%. The pfcrt SVMNT haplotype was also found to be present in clinical isolates from Ethiopia. The pfcrt CVMNK-sensitive haplotypes were frequently observed (95.9%). The pfmdr1 mutation N86Y was observed only in 14.9% compared to 85.1% of the clinical isolates that carried sensitive alleles. Also, the sensitive pfmdr1 Y184 allele was more common, in 94.9% of clinical isolates. None of the investigated P. falciparum clinical isolates carried S1034C, N1042D and D1246Y pfmdr1 polymorphisms. All investigated P. falciparum clinical isolates from Southern and Eastern Ethiopia carried only a single copy of the mutant pfmdr1 gene.
The study reports for the first time the return of chloroquine sensitive P. falciparum in Ethiopia. These findings support the rationale for the use of CQ-based combination drugs as a possible future alternative.
恶性疟原虫抗药性增强，导致埃塞俄比亚停用抗疟药物氯喹和磺胺多辛-乙胺嘧啶。自2004年以来，蒿甲醚-本芴醇一直用于治疗非复杂性恶性疟原虫疟疾。然而，关于青蒿素治疗后疟原虫清除延迟的报告不断增加，这给抗疟治疗带来了新的挑战。随着氯喹完全退出恶性疟原虫疟疾治疗，本研究通过调查埃塞俄比亚南部和东部地区恶性疟原虫中pfmdr1和pfcrt基因以及间日疟原虫中pvmdr1基因的突变等位基因流行情况，评估氯喹抗性的演变。
在埃塞俄比亚南部基层卫生机构就诊的1416例发热患者中，招募了329例恶性疟原虫或间日疟原虫检测呈阳性的发热患者。同样，在埃塞俄比亚东部的1304例发热患者中，81例恶性疟原虫或间日疟原虫检测呈阳性的发热患者被纳入研究。在从疟疾患者采集的410份手指刺血样本中，我们采用直接测序法调查pfcrt和pfmdr1的突变流行情况。这包括测定195例恶性疟原虫临床分离株中pfmdr1的基因拷贝数，以及215例间日疟原虫临床分离株中pvmdr1位点的突变情况。
在调查的恶性疟原虫临床分离株中，84.1%观察到pfcrt K76氯喹敏感等位基因。pfcrt双突变（K76T和C72S）观察到的比例不到3%。还发现埃塞俄比亚临床分离株中存在pfcrt SVMNT单倍型。经常观察到pfcrt CVMNK敏感单倍型（95.9%）。与携带敏感等位基因的85.1%临床分离株相比，pfmdr1突变N86Y仅在14.9%的分离株中观察到。此外，敏感的pfmdr1 Y184等位基因更常见，在94.9%的临床分离株中存在。调查的恶性疟原虫临床分离株均未携带pfmdr1多态性S1034C、N1042D和D1246Y。埃塞俄比亚南部和东部所有调查的恶性疟原虫临床分离株仅携带单拷贝突变pfmdr1基因。
该研究首次报告了埃塞俄比亚出现对氯喹敏感的恶性疟原虫。这些发现支持了将基于氯喹的联合药物作为未来可能替代药物的合理性。
