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PloS One 2024Single nucleotide polymorphisms (SNPs) in the Plasmodium falciparum multi-drug resistance protein 1 (Pfmrp1) gene have previously been reported to confer resistance to...
Increased sensitivity of malaria parasites to common antimalaria drugs after the introduction of artemether-lumefantrine: Implication of policy change and implementation of more effective drugs in fight against malaria.
Single nucleotide polymorphisms (SNPs) in the Plasmodium falciparum multi-drug resistance protein 1 (Pfmrp1) gene have previously been reported to confer resistance to Artemisinin-based Combination Therapies (ACTs) in Southeast Asia. A total of 300 samples collected from six sites between 2008 and 2019 under an ongoing malaria drug sensitivity patterns in Kenya study were evaluated for the presence of SNPs at Pfmrp1 gene codons: H191Y, S437A, I876V, and F1390I using the Agena MassARRAY® platform. Each isolate was further tested against artemisinin (ART), lumefantrine (LU), amodiaquine (AQ), mefloquine (MQ), quinine (QN), and chloroquine (CQ) using malaria the SYBR Green I-based method to determine their in vitro drug sensitivity. Of the samples genotyped, polymorphism at Pfmrp1 codon I876V was the most frequent, with 59.3% (163/275) mutants, followed by F1390I, 7.2% (20/278), H191Y, 4.0% (6/151), and S437A, 3.3% (9/274). A significant decrease in median 50% inhibition concentrations (IC50s) and interquartile range (IQR) was noted; AQ from 2.996 ng/ml [IQR = 2.604-4.747, n = 51] in 2008 to 1.495 ng/ml [IQR = 0.7134-3.318, n = 40] (P<0.001) in 2019, QN from 59.64 ng/ml [IQR = 29.88-80.89, n = 51] in 2008 to 18.10 ng/ml [IQR = 11.81-26.92, n = 42] (P<0.001) in 2019, CQ from 35.19 ng/ml [IQR = 16.99-71.20, n = 30] in 2008 to 6.699 ng/ml [IQR = 4.976-9.875, n = 37] (P<0.001) in 2019, and ART from 2.680 ng/ml [IQR = 1.608-4.857, n = 57] in 2008 to 2.105 ng/ml [IQR = 1.266-3.267, n = 47] (P = 0.0012) in 2019, implying increasing parasite sensitivity to the drugs over time. However, no significant variations were observed in LU (P = 0.2692) and MQ (P = 0.0939) respectively, suggesting stable parasite responses over time. There was no statistical significance between the mutation at 876 and parasite sensitivity to selected antimalarials tested, suggesting stable sensitivity for the parasites with 876V mutations. These findings show that Kenyan parasite strains are still sensitive to AQ, QN, CQ, ART, LU, and MQ. Despite the presence of Pfmrp1 mutations in parasites among the population.
Topics: Antimalarials; Humans; Plasmodium falciparum; Artemether, Lumefantrine Drug Combination; Malaria, Falciparum; Polymorphism, Single Nucleotide; Multidrug Resistance-Associated Proteins; Kenya; Mefloquine; Amodiaquine; Drug Resistance; Artemisinins; Chloroquine; Quinine; Male; Female
PubMed: 38900782
DOI: 10.1371/journal.pone.0298585 -
Heliyon May 2024[This corrects the article DOI: 10.1016/j.heliyon.2023.e22187.].
[This corrects the article DOI: 10.1016/j.heliyon.2023.e22187.].
PubMed: 38887381
DOI: 10.1016/j.heliyon.2024.e30645 -
International Journal of Infectious... Jun 2024Intermittent Preventive Treatment of schoolchildren (IPTsc) is recommended by WHO as a strategy to protect against malaria; To explore whether IPTsc with...
OBJECTIVE
Intermittent Preventive Treatment of schoolchildren (IPTsc) is recommended by WHO as a strategy to protect against malaria; To explore whether IPTsc with dihydroartemisinin-piperaquine (DP) or artesunate-amodiaquine (ASAQ) cause a selection of molecular markers in Plasmodium falciparum genes associated with resistance in children in seven schools in Tanga region, Tanzania.
METHODS
SNPs in P. falciparum genes Pfmdr1, Pfexo, Pfkelch13 and Pfcrt and copy number variations in Pfplasmepsin-2 and Pfmdr1 were assessed in samples collected at 12 months (visit 4, n=74) and 20 months (visit 6, n=364) after initiation of IPTsc and compared with the baseline prevalence (n=379).
RESULTS
The prevalence of Pfmdr1 N86 and Pfexo 415G was >99% and 0%, respectively without any temporal differences observed. The prevalence of Pfmdr1 184F changed significantly from baseline (52.2%) to visit 6 (64.6%) (χ=6.11, p=0.013), but no differences were observed between the treatment arms (χ=0.05, p=0.98). Finally, only minor differences in the amplification of Pfmdr1 were observed; from 10.2% at baseline to 16.7% at visit 6 (χ=0.98, p=0.32).
CONCLUSIONS
The IPTsc strategy does not seem to pose a risk for the selection of markers associated with DP or ASAQ resistance. Continuously and timely surveillance of markers of antimalarial drug resistance is recommended.
PubMed: 38876161
DOI: 10.1016/j.ijid.2024.107102 -
Tropical Medicine & International... Jun 2024Seasonal malaria chemoprevention using sulfadoxine-pyrimethamine plus amodiaquine (sulfadoxine-pyrimethamine plus amodiaquine on Day 1 and amodiaquine on both Day 2 and...
Impact of seasonal malaria chemoprevention based on the number of medicines doses received on malaria burden among children aged 3-59 months in Nigeria: A propensity score-matched analysis.
BACKGROUND
Seasonal malaria chemoprevention using sulfadoxine-pyrimethamine plus amodiaquine (sulfadoxine-pyrimethamine plus amodiaquine on Day 1 and amodiaquine on both Day 2 and Day 3) is delivered to children aged 3-59 months in areas of highly season malaria transmission. While the overall population-level impact of seasonal malaria chemoprevention on malaria control has been documented in various countries and time periods, there is no clear evidence regarding seasonal malaria chemoprevention impact based on the number of medicine doses children receive in one cycle in routine programmatic conditions.
METHODS
Data were extracted from Nigeria's routinely collected seasonal malaria chemoprevention end-of-round coverage surveys (2021, 2022). We matched seasonal malaria chemoprevention-targeted children who received specific numbers of seasonal malaria chemoprevention medicines with those who did not receive any doses of seasonal malaria chemoprevention medicines (non-sulfadoxine-pyrimethamine plus amodiaquine) using multiple sets of propensity score matches. We performed multilevel logistic regression for each matched group to evaluate the association between the number of doses of seasonal malaria chemoprevention medicines and monthly confirmed malaria cases (caregiver-reported malaria infection diagnosed by rapid diagnostic test at a health facility following the penultimate cycle of seasonal malaria chemoprevention).
RESULTS
Among 21,621 SMC-targeted children, 9.7% received non-sulfadoxine-pyrimethamine plus amodiaquine, 0.5% received only Day 1 sulfadoxine-pyrimethamine plus amodiaquine, 1.0% received Day 1 sulfadoxine-pyrimethamine plus amodiaquine and either Day 2 amodiaquine or Day 3 amodiaquine (sulfadoxine-pyrimethamine plus amodiaquine + amodiaquine), and 88.8% received Day 1 sulfadoxine-pyrimethamine plus amodiaquine and both Day 2 and Day 3 amodiaquine (sulfadoxine-pyrimethamine plus amodiaquine + amodiaquine + amodiaquine). Children receiving only Day 1 sulfadoxine-pyrimethamine plus amodiaquine did not have significant lower odds of rapid diagnostic tests-confirmed malaria than those receiving non-sulfadoxine-pyrimethamine plus amodiaquine (OR 0.77, 0.42-1.42). However, children receiving sulfadoxine-pyrimethamine plus amodiaquine + amodiaquine had significantly lower odds of rapid diagnostic tests-confirmed malaria than those receiving non-sulfadoxine-pyrimethamine plus amodiaquine (OR 0.42, 95% CI 0.28-0.63). Similarly, children receiving sulfadoxine-pyrimethamine plus amodiaquine + amodiaquine + amodiaquine also had significantly lower odds of rapid diagnostic test-confirmed malaria than those receiving non-sulfadoxine-pyrimethamine plus amodiaquine (OR 0.54, 95% CI 0.47-0.62).
CONCLUSION
Adherence to at least one daily dose of amodiaquine administration following receipt of Day 1 sulfadoxine-pyrimethamine plus amodiaquine by eligible children is crucial to ensure the effectiveness of seasonal malaria chemoprevention. This demonstrates the importance of enhancing caregiver awareness regarding the importance of amodiaquine and identifying barriers toward amodiaquine administration at the community level.
PubMed: 38842452
DOI: 10.1111/tmi.14019 -
F1000Research 2021Antimalarial drug resistance is a major challenge hampering malaria control and elimination. About three-quarters of Eritrea's population resides in the malaria-endemic...
BACKGROUND
Antimalarial drug resistance is a major challenge hampering malaria control and elimination. About three-quarters of Eritrea's population resides in the malaria-endemic western lowlands of the country. , the leading causative parasite species, has developed resistance to basically all antimalarials. Continued surveillance of drug resistance using genetic markers provides important molecular data for treatment policies which complements clinical studies, and strengthens control efforts. This study sought to genotype point mutations associated with resistance to sulfadoxine-pyrimethamine and artemisinin, in dried-blood spots from three hospitals in the western lowlands of Eritrea.
METHODS
Dried-blood spot samples were collected from patients visiting Adi Quala, Keren and Gash Barka Hospitals, between July and October, 2014. The patients were followed up after treatment with first line artesunate-amodiaquine, and dried-blood spots were collected on day three after treatment. Nested polymerase chain reaction and Sanger sequencing techniques were employed to genotype point mutations in the (PF3D7_0417200), (PF3D7_0810800) and (PF3D7_1343700) partial gene regions.
RESULTS
Sequence data analyses of PCR-positive isolates found wild-type artemisinin haplotypes associated with resistance (Y493Y, R539R, I543I) in three isolates, whereas four mutant antifolate haplotypes associated with resistance were observed in six isolates. These included the triple-mutant (S108N, C59R, N51I) haplotype, the double-mutant (N51I, S108N) haplotype, the single-mutant (K540E) haplotype, and the mixed-mutant (S108N, N51I + K540E) haplotype. Other findings observed were, a rare non-synonymous V45A mutation in four isolates, and a synonymous R449R in one isolate.
CONCLUSIONS
The mutant antifolate haplotypes observed indicate a likely existence of full SP resistance. Further studies can be carried out to estimate the prevalence of SP resistance. The wild-type artemisinin haplotypes observed suggest artemisinin is still an effective treatment. Continuous monitoring of point mutations associated with delayed parasite clearance in ART clinical studies is recommended.
PubMed: 38840941
DOI: 10.12688/f1000research.54195.3 -
Antimalarial resistance risk in Mozambique detected by a novel quadruplex droplet digital PCR assay.Antimicrobial Agents and Chemotherapy May 2024While the malaria parasite continues to cause severe disease globally, Mozambique is disproportionally represented in malaria case totals. Acquisition of copy number...
While the malaria parasite continues to cause severe disease globally, Mozambique is disproportionally represented in malaria case totals. Acquisition of copy number variations (CNVs) in the parasite genome contributes to antimalarial drug resistance through overexpression of drug targets. Of interest, piperaquine resistance is associated with plasmepsin 2 and 3 CNVs ( and respectively), while CNVs in the multidrug efflux pump, multidrug resistance-1 (), increase resistance to amodiaquine and lumefantrine. These antimalarials are partner drugs in artemisinin combination therapies (ACTs) and therefore, CNV detection with accurate and efficient tools is necessary to track ACT resistance risk. Here, we evaluated ~300 clinically derived samples collected from three sites in Mozambique for resistance-associated CNVs. We developed a novel, medium-throughput, quadruplex droplet digital PCR (ddPCR) assay to simultaneously quantify the copy number of , and loci in these clinical samples. By using DNA from laboratory parasite lines, we show that this nanodroplet-based method is capable of detecting picogram levels of parasite DNA, which facilitates its application for low yield and human host-contaminated clinical surveillance samples. Following ddPCR and the application of quality control standards, we detected CNVs in 13 of 229 high-quality samples (prevalence of 5.7%). Overall, our study revealed a low number of resistance CNVs present in the parasite population across all three collection sites, including various combinations of , , and CNVs. The potential for future ACT resistance across Mozambique emphasizes the need for continued molecular surveillance across the region.
PubMed: 38771031
DOI: 10.1128/aac.00346-24 -
Malaria Journal May 2024Emerging artemisinin partial resistance and diagnostic resistance are a threat to malaria control in Africa. Plasmodium falciparum kelch13 (k13) propeller-domain...
BACKGROUND
Emerging artemisinin partial resistance and diagnostic resistance are a threat to malaria control in Africa. Plasmodium falciparum kelch13 (k13) propeller-domain mutations that confer artemisinin partial resistance have emerged in Africa. k13-561H was initially described at a frequency of 7.4% from Masaka in 2014-2015, but not present in nearby Rukara. By 2018, 19.6% of isolates in Masaka and 22% of isolates in Rukara contained the mutation. Longitudinal monitoring is essential to inform control efforts. In Rukara, an assessment was conducted to evaluate recent k13-561H prevalence changes, as well as other key mutations. Prevalence of hrp2/3 deletions was also assessed.
METHODS
Samples collected in Rukara in 2021 were genotyped for key artemisinin and partner drug resistance mutations using molecular inversion probe assays and for hrp2/3 deletions using qPCR.
RESULTS
Clinically validated k13 artemisinin partial resistance mutations continue to increase in prevalence with the overall level of mutant infections reaching 32% in Rwanda. The increase appears to be due to the rapid emergence of k13-675V (6.4%, 6/94 infections), previously not observed, rather than continued expansion of 561H (23.5% 20/85). Mutations to partner drugs and other anti-malarials were variable, with high levels of multidrug resistance 1 (mdr1) N86 (95.5%) associated with lumefantrine decreased susceptibility and dihydrofolate reductase (dhfr) 164L (24.7%) associated with a high level of antifolate resistance, but low levels of amodiaquine resistance polymorphisms with chloroquine resistance transporter (crt) 76T: at 6.1% prevalence. No hrp2 or hrp3 gene deletions associated with diagnostic resistance were found.
CONCLUSIONS
Increasing prevalence of artemisinin partial resistance due to k13-561H and the rapid expansion of k13-675V is concerning for the longevity of artemisinin effectiveness in the region. False negative RDT results do not appear to be an issue with no hrp2 or hpr3 deletions detected. Continued molecular surveillance in this region and surrounding areas is needed to follow artemisinin partial resistance and provide early detection of partner drug resistance, which would likely compromise control and increase malaria morbidity and mortality in East Africa.
Topics: Plasmodium falciparum; Artemisinins; Antimalarials; Protozoan Proteins; Drug Resistance; Rwanda; Malaria, Falciparum; Mutation; Humans; Antigens, Protozoan; Prevalence; Child; Young Adult; Adolescent; Adult; Child, Preschool
PubMed: 38755607
DOI: 10.1186/s12936-024-04981-4 -
Frontiers in Cellular and Infection... 2024Routine surveillance for antimalarial drug resistance is critical to sustaining the efficacy of artemisinin-based Combination Therapies (ACTs). and non- artemisinin...
BACKGROUND
Routine surveillance for antimalarial drug resistance is critical to sustaining the efficacy of artemisinin-based Combination Therapies (ACTs). and non- artemisinin ART) resistance-associated mutations are uncommon in Africa. We investigated polymorphisms in actin-binding protein (Pfcoronin associated with reduced sensitivity to ART in Nigeria.
METHODS
Fifty-two malaria subjects who met the inclusion criteria were followed up in a 28-day therapeutic efficacy study of artemether-lumefantrine in Lagos, Nigeria. Parasite detection was done by microscopy and molecular diagnostic approaches involving PCR amplification of genes for 18S rRNA, ATS, telomere-associated repetitive elements-2 (TARE-2). and genes were sequenced bi-directionally while clonality of infections was determined using 12 neutral microsatellite and analyses. Antimalarial drugs (sulfadoxine-pyrimethamine, amodiaquine, chloroquine and some quinolones) resistance variants (DHFR_51, DHFR_59, DHFR_108, DHFR_164, MDR1_86, MDR1_184, DHPS_581 and DHPS_613) were genotyped by high-resolution melting (HRM) analysis.
RESULTS
A total of 7 (26.92%) cases were identified either as early treatment failure, late parasitological failure or late clinical failure. Of the four post-treatment infections identified as recrudescence by genotypes, only one was classified as recrudescence by multilocus microsatellites genotyping. Microsatellite analysis revealed no significant difference in the mean allelic diversity, , (P = 0.19, Mann-Whitney test). Allele sizes and frequency per locus implicated one isolate. Genetic analysis of this isolate identified two new SNVs (I68G and L173F) in addition to the P76S earlier reported. Linkage-Disequilibrium as a standardized association index, , between multiple loci revealed significant LD ( = 0.2865, =0.02, Monte-Carlo simulation) around the neutral microsatellite loci. The drug resistance-associated haplotypes combinations, (108/51164/59/581/86/184), were observed in two samples.
CONCLUSION
mutations identified in this study, with potential to impact parasite clearance, may guide investigations on emerging ART tolerance in Nigeria, and West African endemic countries.
Topics: Adult; Female; Humans; Male; Antimalarials; Artemether, Lumefantrine Drug Combination; Artemisinins; Drug Combinations; Drug Resistance; Genotype; Malaria, Falciparum; Microfilament Proteins; Microsatellite Repeats; Mutation; Nigeria; Plasmodium falciparum; Polymorphism, Genetic; Protozoan Proteins; Recurrence
PubMed: 38716192
DOI: 10.3389/fcimb.2024.1366563 -
BioRxiv : the Preprint Server For... Apr 2024The bitter taste of medicines hinders patient compliance, but not everyone experiences these difficulties because people worldwide differ in their bitterness perception....
The bitter taste of medicines hinders patient compliance, but not everyone experiences these difficulties because people worldwide differ in their bitterness perception. To better understand how people from diverse ancestries perceive medicines and taste modifiers, 338 adults, European and recent US and Canada immigrants from Asia, South Asia, and Africa, rated the bitterness intensity of taste solutions on a 100-point generalized visual analog scale and provided a saliva sample for genotyping. The taste solutions were five medicines, tenofovir alafenamide (TAF), moxifloxacin, praziquantel, amodiaquine, and propylthiouracil (PROP), and four other solutions, TAF mixed with sucralose (sweet, reduces bitterness) or 6-methylflavone (tasteless, reduces bitterness), sucralose alone, and sodium chloride alone. Bitterness ratings differed by ancestry for two of the five drugs (amodiaquine and PROP) and for TAF mixed with sucralose. Genetic analysis showed that people with variants in one bitter receptor variant gene (38) reported PROP was more bitter than did those with a different variant (p= 7.6e-19) and that people with either an or a genotype found sucralose more bitter than did others (p=2.6e-8, p=7.9e-11, resp.). Our findings may help guide the formulation of bad-tasting medicines to meet the needs of those most sensitive to them.
PubMed: 38712219
DOI: 10.1101/2024.04.24.590957 -
The Lancet. Microbe May 2024Artemether-lumefantrine is widely used for uncomplicated Plasmodium falciparum malaria; sulfadoxine-pyrimethamine plus amodiaquine is used for seasonal malaria...
Artemether-lumefantrine with or without single-dose primaquine and sulfadoxine-pyrimethamine plus amodiaquine with or without single-dose tafenoquine to reduce Plasmodium falciparum transmission: a phase 2, single-blind, randomised clinical trial in Ouelessebougou, Mali.
BACKGROUND
Artemether-lumefantrine is widely used for uncomplicated Plasmodium falciparum malaria; sulfadoxine-pyrimethamine plus amodiaquine is used for seasonal malaria chemoprevention. We aimed to determine the efficacy of artemether-lumefantrine with and without primaquine and sulfadoxine-pyrimethamine plus amodiaquine with and without tafenoquine for reducing gametocyte carriage and transmission to mosquitoes.
METHODS
In this phase 2, single-blind, randomised clinical trial conducted in Ouelessebougou, Mali, asymptomatic individuals aged 10-50 years with P falciparum gametocytaemia were recruited from the community and randomly assigned (1:1:1:1) to receive either artemether-lumefantrine, artemether-lumefantrine with a single dose of 0·25 mg/kg primaquine, sulfadoxine-pyrimethamine plus amodiaquine, or sulfadoxine-pyrimethamine plus amodiaquine with a single dose of 1·66 mg/kg tafenoquine. All trial staff other than the pharmacist were masked to group allocation. Participants were not masked to group allocation. Randomisation was done with a computer-generated randomisation list and concealed with sealed, opaque envelopes. The primary outcome was the median within-person percent change in mosquito infection rate in infectious individuals from baseline to day 2 (artemether-lumefantrine groups) or day 7 (sulfadoxine-pyrimethamine plus amodiaquine groups) after treatment, assessed by direct membrane feeding assay. All participants who received any trial drug were included in the safety analysis. This study is registered with ClinicalTrials.gov, NCT05081089.
FINDINGS
Between Oct 13 and Dec 16, 2021, 1290 individuals were screened and 80 were enrolled and randomly assigned to one of the four treatment groups (20 per group). The median age of participants was 13 (IQR 11-20); 37 (46%) of 80 participants were female and 43 (54%) were male. In individuals who were infectious before treatment, the median percentage reduction in mosquito infection rate 2 days after treatment was 100·0% (IQR 100·0-100·0; n=19; p=0·0011) with artemether-lumefantrine and 100·0% (100·0-100·0; n=19; p=0·0001) with artemether-lumefantrine with primaquine. Only two individuals who were infectious at baseline infected mosquitoes on day 2 after artemether-lumefantrine and none at day 5. By contrast, the median percentage reduction in mosquito infection rate 7 days after treatment was 63·6% (IQR 0·0-100·0; n=20; p=0·013) with sulfadoxine-pyrimethamine plus amodiaquine and 100% (100·0-100·0; n=19; p<0·0001) with sulfadoxine-pyrimethamine plus amodiaquine with tafenoquine. No grade 3-4 or serious adverse events occurred.
INTERPRETATION
These data support the effectiveness of artemether-lumefantrine alone for preventing nearly all mosquito infections. By contrast, there was considerable post-treatment transmission after sulfadoxine-pyrimethamine plus amodiaquine; therefore, the addition of a transmission-blocking drug might be beneficial in maximising its community impact.
FUNDING
Bill & Melinda Gates Foundation.
PubMed: 38705163
DOI: 10.1016/S2666-5247(24)00023-5