scholarly journals Emergence and Spread of kelch13 Mutations Associated with Artemisinin Resistance in Plasmodium falciparum Parasites in 12 Thai Provinces from 2007 to 2016

2018 ◽  
Vol 62 (4) ◽  
Author(s):  
Theerayot Kobasa ◽  
Eldin Talundzic ◽  
Rungniran Sug-aram ◽  
Patcharida Boondat ◽  
Ira F. Goldman ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Gene Mutations ◽  
Artemisinin Resistance ◽  
Parasite Clearance ◽  
Resistance Mutations ◽  
Content Type ◽  
Artemisinin Derivatives ◽  
Reduced Ring ◽  
Control And Prevention ◽  
Greater Mekong Subregion

ABSTRACT Artemisinin-based combination therapy (ACT) is the most effective and widely used treatment for uncomplicated Plasmodium falciparum malaria and is a cornerstone for malaria control and prevention globally. Resistance to artemisinin derivatives has been confirmed in the Greater Mekong Subregion (GMS) and manifests as slow parasite clearance in patients and reduced ring stage susceptibility to artemisinins in survival assays. The P. falciparum kelch13 gene mutations associated with artemisinin-resistant parasites are now widespread in the GMS. We genotyped 277 samples collected during an observational study from 2012 to 2016 from eight provinces in Thailand to identify P. falciparum kelch13 mutations. The results were combined with previously reported genotyping results from Thailand to construct a map illustrating the evolution of P. falciparum kelch13 mutations from 2007 to 2016 in that country. Different mutant alleles were found in strains with different geographical origins. The artemisinin resistance-conferring Y493H and R539T mutations were detected mainly in eastern Thailand (bordering Cambodia), while P574L was found only in western Thailand and R561H only in northwestern Thailand. The C580Y mutation was found across the entire country and was nearing fixation along the Thai-Cambodia border. Overall, the prevalence of artemisinin resistance mutations increased over the last 10 years across Thailand, especially along the Thai-Cambodia border. Molecular surveillance and therapeutic efficacy monitoring should be intensified in the region to further assess the extent and spread of artemisinin resistance.

scholarly journals K13 Propeller Mutations in Plasmodium falciparum Populations in Regions of Malaria Endemicity in Vietnam from 2009 to 2016

2017 ◽  
Vol 61 (4) ◽  
Author(s):  
Nguyen Thuy-Nhien ◽  
Nguyen Kim Tuyen ◽  
Nguyen Thanh Tong ◽  
Nguyen Tuong Vy ◽  
Ngo Viet Thanh ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Artemisinin Resistance ◽  
Parasite Clearance ◽  
Single Strain ◽  
Content Type ◽  
Reduced Ring ◽  
Resistance Markers ◽  
Multiple Strains

ABSTRACT The spread of artemisinin-resistant Plasmodium falciparum compromises the therapeutic efficacy of artemisinin combination therapies (ACTs) and is considered the greatest threat to current global initiatives to control and eliminate malaria. This is particularly relevant in Vietnam, where dihydroartemisinin-piperaquine (DP) is the recommended ACT for P. falciparum infection. The propeller domain gene of K13, a molecular marker of artemisinin resistance, was successfully sequenced in 1,060 P. falciparum isolates collected at 3 malaria hot spots in Vietnam between 2009 and 2016. Eight K13 propeller mutations (Thr474Ile, Tyr493His, Arg539Thr, Ile543Thr, Pro553Leu, Val568Gly, Pro574Leu, and Cys580Tyr), including several that have been validated to be artemisinin resistance markers, were found. The prevalences of K13 mutations were 29% (222/767), 6% (11/188), and 43% (45/105) in the Binh Phuoc, Ninh Thuan, and Gia Lai Provinces of Vietnam, respectively. Cys580Tyr became the dominant genotype in recent years, with 79.1% (34/43) of isolates in Binh Phuoc Province and 63% (17/27) of isolates in Gia Lai Province carrying this mutation. K13 mutations were associated with reduced ring-stage susceptibility to dihydroartemisinin (DHA) in vitro and prolonged parasite clearance in vivo. An analysis of haplotypes flanking K13 suggested the presence of multiple strains with the Cys580Tyr mutation rather than a single strain expanding across the three sites.

scholarly journals Efficacy of dihydroartemisinin/piperaquine and artesunate monotherapy for the treatment of uncomplicated Plasmodium falciparum malaria in Central Vietnam

2020 ◽  
Author(s):  
Eduard Rovira-Vallbona ◽  
Nguyen Van Hong ◽  
Johanna H Kattenberg ◽  
Ro Mah Huan ◽  
Nguyen Thi Thu Hien ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Falciparum Malaria ◽  
Ex Vivo ◽  
Survival Rates ◽  
Artemisinin Resistance ◽  
Plasmodium Falciparum Malaria ◽  
Parasite Clearance ◽  
Resistance Mutations ◽  
Malaria Burden ◽  
Central Vietnam

Abstract Background Artemisinin-based combination therapies (ACTs) have significantly contributed to reduce Plasmodium falciparum malaria burden in Vietnam, but their efficacy is challenged by treatment failure of dihydroartemisinin/piperaquine ACT in Southern provinces. Objectives To assess the efficacy of dihydroartemisinin/piperaquine for uncomplicated P. falciparum malaria in Gia Lai, Central Vietnam, and determine parasite resistance to artemisinin (ClinicalTrials.gov identifier NCT02604966). Methods Sixty patients received either dihydroartemisinin/piperaquine (4 mg/kg/day, 3 days; n = 33) or artesunate monotherapy (4 mg/kg/day, 3 days; n = 27) followed by dihydroartemisinin/piperaquine (AS + DHA/PPQ). Clinical phenotypes were determined during a 42 day follow-up and analysed together with ex vivo susceptibility to antimalarials and molecular markers of drug resistance. Results Day 3 positivity rate was significantly higher in the AS + DHA/PPQ arm compared with dihydroartemisinin/piperaquine (70.4% versus 39.4%, P = 0.016). Parasite clearance time was 95.2 h (AS + DHA/PPQ) versus 71.9 h (dihydroartemisinin/piperaquine, P = 0.063) and parasite clearance half-life was 7.4 h (AS + DHA/PPQ) versus 7.0 h (dihydroartemisinin/piperaquine, P = 0.140). Adequate clinical and parasitological response at Day 42 was 100% in both arms. By RT–qPCR, 36% (19/53) patients remained positive until Day 7. No recurrences were detected. kelch13 artemisinin resistance mutations were found in 87% (39/45) of isolates and 50% (20/40) were KEL1/C580Y. The piperaquine resistance marker plasmepsin-2 was duplicated in 10.4% (5/48). Isolates from Day 3-positive patients (n = 18) had higher ex vivo survival rates to artemisinin compounds (P < 0.048) and prevalence of kelch13 mutations (P = 0.005) than Day 3-negative patients (n = 5). The WHO definition of artemisinin resistance was fulfilled in 60% (24/40) of cases. Conclusions Although dihydroartemisinin/piperaquine remained effective to treat P. falciparum, the high Day 3 positivity rate and prevalence of KEL1 strains calls for continuous monitoring of dihydroartemisinin/piperaquine efficacy in Central Vietnam.

scholarly journals Delayed Parasite Clearance after Treatment with Dihydroartemisinin-Piperaquine in Plasmodium falciparum Malaria Patients in Central Vietnam

2014 ◽  
Vol 58 (12) ◽  
pp. 7049-7055 ◽  
Author(s):  
Kamala Thriemer ◽  
Nguyen Van Hong ◽  
Anna Rosanas-Urgell ◽  
Bui Quang Phuc ◽  
Do Manh Ha ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Clearance Rate ◽  
Artemisinin Resistance ◽  
Parasite Clearance ◽  
Clearance Time ◽  
Sensitivity Testing ◽  
Content Type ◽  
Parasite Clearance Time ◽  
Central Vietnam

ABSTRACTReduced susceptibility ofPlasmodium falciparumtoward artemisinin derivatives has been reported from the Thai-Cambodian and Thai-Myanmar borders. Following increasing reports from central Vietnam of delayed parasite clearance after treatment with dihydroartemisinin-piperaquine (DHA-PPQ), the current first-line treatment, we carried out a study on the efficacy of this treatment. Between September 2012 and February 2013, we conducted a 42-dayin vivoandin vitroefficacy study in Quang Nam Province. Treatment was directly observed, and blood samples were collected twice daily until parasite clearance. In addition, genotyping, quantitative PCR (qPCR), andin vitrosensitivity testing of isolates was performed. The primary endpoints were parasite clearance rate and time. The secondary endpoints included PCR-corrected and uncorrected cure rates, qPCR clearance profiles,in vitrosensitivity results (for chloroquine, dihydroartemisinin, and piperaquine), and genotyping for mutations in the Kelch 13 propeller domain. Out of 672 screened patients, 95 were recruited and 89 available for primary endpoint analyses. The median parasite clearance time (PCT) was 61.7 h (interquartile range [IQR], 47.6 to 83.2 h), and the median parasite clearance rate had a slope half-life of 6.2 h (IQR, 4.4 to 7.5 h). The PCR-corrected efficacy rates were estimated at 100% at day 28 and 97.7% (95% confidence interval, 91.2% to 99.4%) at day 42. At day 3, theP. falciparumprevalence by qPCR was 2.5 times higher than that by microscopy. The 50% inhibitory concentrations (IC50s) of isolates with delayed clearance times (≥72 h) were significantly higher than those with normal clearance times for all three drugs. Delayed parasite clearance (PCT, ≥72 h) was significantly higher among day 0 samples carrying the 543 mutant allele (47.8%) than those carrying the wild-type allele (1.8%;P= 0.048). In central Vietnam, the efficacy of DHA-PPQ is still satisfactory, but the parasite clearance time and rate are indicative of emerging artemisinin resistance. (This study has been registered at ClinicalTrials.gov under registration no. NCT01775592.)

scholarly journals Molecular Profile of Malaria Drug Resistance Markers of Plasmodium falciparum in Suriname

2017 ◽  
Vol 61 (7) ◽  
Author(s):  
Stella M. Chenet ◽  
Sheila Akinyi Okoth ◽  
Julia Kelley ◽  
Naomi Lucchi ◽  
Curtis S. Huber ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Therapeutic Efficacy ◽  
Artemisinin Resistance ◽  
Molecular Profile ◽  
Resistance Mutations ◽  
Molecular Surveillance ◽  
Content Type ◽  
Resistance Markers ◽  
High Parasite

ABSTRACT In Suriname, an artesunate monotherapy therapeutic efficacy trial was recently conducted to evaluate partial artemisinin resistance emerging in Plasmodium falciparum. We genotyped the PfK13 propeller domain of P. falciparum in 40 samples as well as other mutations proposed to be associated with artemisinin-resistant mutants. We did not find any mutations previously associated with artemisinin resistance in Southeast Asia, but we found fixed resistance mutations for chloroquine (CQ) and sulfadoxine-pyrimethamine. Additionally, the PfCRT C350R mutation, associated with reversal of CQ resistance and piperaquine-selective pressure, was present in 62% of the samples. Our results from neutral microsatellite data also confirmed a high parasite gene flow in the Guiana Shield. Although recruiting participants for therapeutic efficacy studies is challenging in areas where malaria endemicity is very low due to the low number of malaria cases reported, conducting these studies along with molecular surveillance remains essential for the monitoring of artemisinin-resistant alleles and for the characterization of the population structure of P. falciparum in areas targeted for malaria elimination.

scholarly journals Clinical efficacy of artemisinin-lumefantrine and status of antifolate drug resistance markers in western Kenya

2019 ◽  
Author(s):  
gabriel m kishoyian ◽  
Eliud N.M. Njagi ◽  
George O. Orinda ◽  
Kevin Thiongo ◽  
Francis T. Kimani ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Molecular Markers ◽  
Clinical Efficacy ◽  
Gene Mutations ◽  
Parasite Clearance ◽  
Specific Gene ◽  
Artemisinin Derivatives ◽  
Drug Of Choice ◽  
Study Population ◽  
Parasitological Response

Abstract Background: The development of Plasmodium falciparum resistance to sulfadoxine-pyrimethamine (SP) necessitated its replacement with artemether-lumefantrine (AL) in Kenya. However, the delayed parasite clearance following treatment with artemisinin derivatives has now spread in the Greater Mekong Sub region and may emerge or spread to other malaria endemic regions. Since parasites resistance to drugs is correlated with specific gene mutations, molecular markers associated with antimalarial drugs offer a powerful tool to monitor the emergence and spread of resistance. In this study, we assessed the clinical efficacy of AL following its adoption and the current levels of antifolate drug resistant markers after its ban in Kenyan health facilities. Methods: We conducted a therapeutic efficacy study between May and November 2015 in Chulaimbo sub-County, Kisumu, Kenya. A total of 76 patients ≥6 and ≤60 months of age with confirmed Plasmodium falciparum mono-infection were enrolled, treated with AL and followed up for a period of 28 days. Study endpoints were adequate clinical and parasitological response (ACPR) on the 28 day and known SP molecular markers of resistance were also determined. Results: The study showed that 97% of the participants had cleared parasitemia within 48 hours with an adequate clinical and parasitological response (ACPR) of 100% clearance on day 3. On Pfdhfr/Pfdhps mutants, N51I was identified in the P. falciparum isolates with a prevalence of 94% while C59R and S108N had 92% each. The prevalence of mutation at Pfdhps codons A437G and K540E stood at 94% and 91% respectively. Conclusion: AL was found to be highly efficacious since no plasmodium falciparum parasites were observed after day 3 making it a drug of choice in Kenya. Evidence of quintuple mutations frequency is high in the study population threatening the future use of SP.

scholarly journals Laboratory Detection of Artemisinin-Resistant Plasmodium falciparum

2014 ◽  
Vol 58 (6) ◽  
pp. 3157-3161 ◽  
Author(s):  
Kesinee Chotivanich ◽  
Rupam Tripura ◽  
Debashish Das ◽  
Poravuth Yi ◽  
Nicholas P. J. Day ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Parasite Clearance ◽  
Ring Stage ◽  
Clearance Time ◽  
Content Type ◽  
Reduced Ring ◽  
Susceptibility Tests ◽  
Low Sensitivity

ABSTRACTConventional 48-hin vitrosusceptibility tests have low sensitivity in identifying artemisinin-resistantPlasmodium falciparum, defined phenotypically by lowin vivoparasite clearance rates. We hypothesized originally that this discrepancy was explained by a loss of ring-stage susceptibility and so developed a simple field-adapted 24-h trophozoite maturation inhibition (TMI) assay focusing on the ring stage and compared it to the standard 48-h schizont maturation inhibition (WHO) test. In Pailin, western Cambodia, where artemisinin-resistantP. falciparumis prevalent, the TMI test mean (95% confidence interval) 50% inhibitory concentration (IC50) for artesunate was 6.8 (5.2 to 8.3) ng/ml compared with 1.5 (1.2 to 1.8) ng/ml for the standard 48-h WHO test (P= 0.001). TMI IC50s correlated significantly with thein vivoresponses to artesunate (parasite clearance time [r= 0.44,P= 0.001] and parasite clearance half-life [r= 0.46,P= 0.001]), whereas the standard 48-h test values did not. On continuous culture of two resistant isolates, the artemisinin-resistant phenotype was lost after 6 weeks (IC50s fell from 10 and 12 ng/ml to 2.7 and 3 ng/ml, respectively). Slow parasite clearance in falciparum malaria in western Cambodia results from reduced ring-stage susceptibility.

scholarly journals Little Polymorphism at the K13 Propeller Locus in Worldwide Plasmodium falciparum Populations Prior to the Introduction of Artemisinin Combination Therapies

2016 ◽  
Vol 60 (6) ◽  
pp. 3340-3347 ◽  
Author(s):  
Toshihiro Mita ◽  
Richard Culleton ◽  
Nobuyuki Takahashi ◽  
Masatoshi Nakamura ◽  
Takahiro Tsukahara ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Haplotype Diversity ◽  
Artemisinin Resistance ◽  
Pairwise Comparison ◽  
Purifying Selection ◽  
Parasite Clearance ◽  
Combination Therapies ◽  
Content Type ◽  
Exposed Population ◽  
Artemisinin Combination Therapies

The emergence and spread of artemisinin-resistantPlasmodium falciparumis of huge concern for the global effort toward malaria control and elimination. Artemisinin resistance, defined as a delayed time to parasite clearance following administration of artemisinin, is associated with mutations in thePfkelch13gene of resistant parasites. To date, as many as 60 nonsynonymous mutations have been identified in this gene, but whether these mutations have been selected by artemisinin usage or merely reflect natural polymorphism independent of selection is currently unknown. To clarify this, we sequenced thePfkelch13propeller domain in 581 isolates collected before (420 isolates) and after (161 isolates) the implementation of artemisinin combination therapies (ACTs), from various regions of endemicity worldwide. Nonsynonymous mutations were observed in 1% of parasites isolated prior to the introduction of ACTs. Frequencies of mutant isolates, nucleotide diversity, and haplotype diversity were significantly higher in the parasites isolated from populations exposed to artemisinin than in those from populations that had not been exposed to the drug. In the artemisinin-exposed population, a significant excess of dN compared to dS was observed, suggesting the presence of positive selection. In contrast, pairwise comparison of dN and dS and the McDonald and Kreitman test indicate that purifying selection acts on thePfkelch13propeller domain in populations not exposed to ACTs. These population genetic analyses reveal a low baseline ofPfkelch13polymorphism, probably due to purifying selection in the absence of artemisinin selection. In contrast, variousPfkelch13mutations have been selected under artemisinin pressure.

scholarly journals Intrahost modeling of artemisinin resistance in Plasmodium falciparum

2010 ◽  
Vol 108 (1) ◽  
pp. 397-402 ◽  
Author(s):  
Sompob Saralamba ◽  
Wirichada Pan-Ngum ◽  
Richard J. Maude ◽  
Sue J. Lee ◽  
Joel Tarning ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Plasmodium Falciparum ◽  
Goodness Of Fit ◽  
Artemisinin Resistance ◽  
Parasite Clearance ◽  
Model Parameters ◽  
Asexual Parasite ◽  
Ring Stage ◽  
Reduced Ring

Artemisinin-resistant Plasmodium falciparum malaria has emerged in western Cambodia. Resistance is characterized by prolonged in vivo parasite clearance times (PCTs) following artesunate treatment. The biological basis is unclear. The hypothesis that delayed parasite clearance results from a stage-specific reduction in artemisinin sensitivity of the circulating young asexual parasite ring stages was examined. A mathematical model was developed, describing the intrahost parasite stage-specific pharmacokinetic–pharmacodynamic relationships. Model parameters were estimated using detailed pharmacokinetic and parasite clearance data from 39 patients with uncomplicated falciparum malaria treated with artesunate from Pailin (western Cambodia) where artemisinin resistance was evident and 40 patients from Wang Pha (northwestern Thailand) where efficacy was preserved. The mathematical model reproduced the observed parasite clearance for each patient with an accurate goodness of fit (rmsd: 0.03–0.67 in log10 scale). The parameter sets that provided the best fits with the observed in vivo data consist of a highly conserved concentration–effect relationship for the trophozoite and schizont parasite stages, but a variable relationship for the ring stages. The model-derived assessment suggests that the efficacy of artesunate on ring stage parasites is reduced significantly in Pailin. This result supports the hypothesis that artemisinin resistance mainly reflects reduced ring-stage susceptibility and predicts that doubling the frequency of dosing will accelerate clearance of artemisinin-resistant parasites.

scholarly journals In vivo delayed clearance of Plasmodium falciparum malaria independent of kelch13 polymorphisms and with escalating malaria in Bangladesh.

2021 ◽  
Author(s):  
Maisha Khair Nima ◽  
Saiful Arefeen Sazed ◽  
Angana Mukherjee ◽  
Muhammad Riadul Haque Hossainey ◽  
Ching Swe Phru ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Half Life ◽  
Artemisinin Combination Therapy ◽  
Artemisinin Resistance ◽  
Plasmodium Falciparum Malaria ◽  
Parasite Clearance ◽  
Resistance Mutations ◽  
Emergence Of Resistance

The emergence of resistance to artemisinin drugs threatens global malaria control. Resistance is widely seen in South East Asia (SEA) and Myanmar, but not comprehensively assessed in Bangladesh. This is due to lack of measuring parasite clearance times in response to drug treatment, a gold standard used to track artemisinin resistance (AR), in the Chittagong Hill Tracts (CHT), where >90% of malaria occurs in Bangladesh. Here we report delay in clinical parasite clearance half-lives > 5 h characteristic of AR, in Bandarban, a south–eastern rural, CHT district with escalating malaria and bordering Myanmar. Thirty–one and 68 malaria patients respectively presented in the clinic in 2018 and 2019, and this increase well correlated to the district–level malaria surge and rise in rainfall, humidity and temperature. A total of 27 patients with uncomplicated Plasmodium falciparum malaria mono–infection, after administration of an artemisinin combination therapy (ACT) showed median (range) parasite clearance half–life and time of 5.6 (1.5 —9.6) and 24 (12—48) hours (h) respectively. The frequency distribution of parasite clearance half–life and time was bimodal, with a slower parasite clearance of 8 h in 20% of the participants. There was however, no detectable parasitemia 72 h after initiating ACT. Half-life clearance of > 5h, respectively seen in 35% and 40% of participants in 2018 and 2019, lacked in correlation to initial parasitemia, blood count parameters or resistance mutations of PfKelch13 (K13, the major parasite marker of AR). Culture adapted strains await assessment of in vitro resistance and new parasite determinants of AR.

scholarly journals The Diversity of the Plasmodium falciparum K13 Propeller Domain Did Not Increase after Implementation of Artemisinin-Based Combination Therapy in Uganda

2019 ◽  
Vol 63 (10) ◽  
Author(s):  
Melissa D. Conrad ◽  
Sam L. Nsobya ◽  
Philip J. Rosenthal
Keyword(s):  
Plasmodium Falciparum ◽  
Southeast Asia ◽  
Artemisinin Resistance ◽  
Standard Of Care ◽  
Parasite Clearance ◽  
Sub Saharan Africa ◽  
Clinical Isolates ◽  
Nucleotide Polymorphisms ◽  
Content Type ◽  
Sub Saharan

ABSTRACT Artemisinin-based combination therapies (ACTs) are the standard of care to treat uncomplicated falciparum malaria. However, resistance to artemisinins, defined as delayed parasite clearance after therapy, has emerged in Southeast Asia, and the spread of resistance to sub-Saharan Africa could have devastating consequences. Artemisinin resistance has been associated in Southeast Asia with multiple nonsynonymous single nucleotide polymorphisms (NS-SNPs) in the propeller domain of the gene encoding the Plasmodium falciparum K13 protein (K13PD). Some K13PD NS-SNPs have been seen in Africa, but the relevance of these mutations is unclear. To assess whether ACT use has selected for specific K13PD mutations, we compared the K13PD genetic diversity in clinical isolates collected before and after the implementation of ACT use from seven sites across Uganda. We detected K13PD NS-SNPs in 16 of 683 (2.3%) clinical isolates collected between 1999 and 2004 and in 26 of 716 (3.6%) isolates collected between 2012 and 2016 (P = 0.16), representing a total of 29 different polymorphisms at 27 codons. Individual NS-SNPs were usually detected only once, and none were found in more than 0.7% of the isolates. Three SNPs (C469F, P574L, and A675V) associated with delayed clearance in Southeast Asia were seen in samples collected between 2012 and 2016, each in a single isolate. No differences in diversity following implementation of ACT use were found at any of the seven sites, nor was there evidence of selective pressures acting on the locus. Our results suggest that selection by ACTs is not impacting on K13PD diversity in Uganda.

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