Artemisinin-based Combination Therapy Research Articles

Comparative Study of Pharmaceutical, Herbal Medicine, and Low-Value Alternating Electromagnetic Radiation as Anti-Malaria Treatment

Malaria is a significant global health burden, particularly in regions with limited healthcare resources. Pharmaceutical interventions, specifically artemisinin-based combination therapies (ACTs), have long been the mainstay of malaria treatment due to their proven efficacy in eliminating Plasmodium parasites. Herbal medicine has also gained attention as a potential alternative or adjunctive therapy. Nevertheless, the emergence of drug-resistant strains, notably in Southeast Asia and Africa, poses a considerable challenge to the effectiveness of these pharmaceutical treatments. Using low-value alternating electromagnetic field (EMF) radiation as an anti-malaria treatment is a novel approach that requires further investigation to determine its therapeutic potential. This research studies the comparative analysis of the effect of pharmaceutical intervention, herbal medicine, and low-value alternating EMF as anti-malaria treatments. The research methodology involves a systematic literature review of relevant scientific databases, design, construction, and administration of 20mT & 30mT electromagnetic field, Lumartem and Thitonia Diversifolia (Jume 12) to plasmodium berghei-infected mice for four days consecutively at the same time interval. Results revealed that all treatments were significantly effective. Lumartem is maximally effective from the third day, while Tihonia Diversifolia was maximally effective on the second day. EMF 10mT was maximally effective on the third day, while EMF 20mT did not fully align with the non-infected mice trend, but it is likely to align if treatment continues. The results of this comparative study will contribute to the body of knowledge regarding the effectiveness of pharmaceutical, herbal medicine, and low-value alternating electromagnetic field treatments for malaria.

Prevalence of multi drug resistance malaria among patients aged 0 – 14 years attending murtala muhammad specialist hospital Kano State, Nigeria

The Plasmodium falciparum multidrug resistance gene 1 (pfmdr1) is a molecular marker of parasite susceptibility to anti-malarial drugs. This study aimed to evaluate multidrug resistance resistance gene 1 (MDR1) mutation in 0-14years old malaria patients attending Murtala Muhammad Specialist Hospital, Kano, Nigeria. Samples from 100 children with malaria were examined to confirm the malaria parasite density and further genotyped via BigDye (v3.1) terminator cycle sequencing for the presence of two SNPs in pfmdr1on samples with high and moderate parasite densities. All data were analyzed using Pearson Chi square and Fisher’s exact (FE) tests. Of the 100 patients, 57% had low (+) malaria parasite density, 28% had moderate (++) and 15% had high (+++) malaria parasite densities of the 100 samples, 31 samples were successfully amplified and analyzed for the pfmdr1 gene located at codon 86 with amplicon size of 534bp while only 7 samples were successfully amplified for the pfmdr1 gene located at codon 1246.Pfmdr1-N86Y mutation was detected in 1 (3.2%) sample. In addition, only 1 (3.2%) sample with allelic change at 1246Y was detected in mutant pfmdr1gene. The result also showed that sex had no significant association (P = 0.4237) with pfmdr1SNP mutation. However, significant association (P = 0.0043) between the age groups (1 month to 14 years) represented in the study and pfmdr1mutation. The present study suggests that strains of P. falciparum with reduced sensitivity to the artemisinin component of artemisinin-based combination therapy (ACT) exist in Kano state, northern Nigeria. Methods: sample Collection Finger prick filter paper blood samples were collected from patients below the age of 5 years. However, 2 mL of venous blood was drawn using sterile syringe and needle from children aged 6 and 14 years. Safety procedures were adopted in the collection of blood samples by swabbing the area to be sampled with disinfectant and allowing it to dry before collection.

Exploring the feasibility of introducing triple artemisinin-based combination therapy in the malaria treatment policy in Vietnam

BackgroundThis study investigates the processes regarding changing malaria treatment policies in Vietnam. Moreover, it explores the feasibility of introducing triple artemisinin-based combination therapy (TACT) in Vietnam to support the national malaria control and elimination plan.MethodsData were collected via 12 in-depth interviews with key stakeholders, combined with a review of policy documents.ResultsTACT is considered as a useful backup strategy in case future treatment failures with current artemisinin-based combination therapy (ACT) would occur. Moreover, TACT is also considered as a promising strategy to prevent the re-establishment of malaria. However, regulatory procedures and implementation timelines for TACT were expected to be lengthy. Therefore, strategies to engage national decision-makers, regulators, and suppliers should be initiated soon, stipulating the benefits of TACT deployment. In Vietnam, a procedure to apply for an import permit without registration that has previously been applied to the introduction of artesunate-pyronaridine was proposed to accelerate the introduction of TACT. Global-level support through the World Health Organization recommendations and prequalification were considered critical for supporting the introduction of TACT in Vietnam.ConclusionsAppropriate approach strategies and early stakeholder engagement will be needed to accelerate the introduction of TACT in Vietnam.

Drug selection pressure and fitness cost for artemether-resistant Plasmodium berghei ANKA parasites in vivo

The clinical use of artemisinin-based combination therapies is threatened by increasing failure rates due to the emergence and spread of multiple drug resistance genes in most human Plasmodium strains. The aim of this study was to generate artemether-resistant (AMR) parasites from Plasmodium berghei ANKA (AMS), and determine their fitness cost. Artemether resistance was generated by increasing drug pressure doses gradually for 9 months. Effective doses (ED50 and ED90) were determined using the 4-day suppressive test, and the indices of resistance (I) at 50% and 90% (I50 and I90) were determined using the ratio of either ED50 or ED90 of AMR to AMS, respectively. The stability of the AMR parasites was evaluated by: five drug-free passages (5DFPs), 3 months of cryopreservation (CP), and drug-free serial passages (DFSPs) for 4 months. Analysis of variance was used to compare differences in growth rates between AMR and AMS with 95% confidence intervals. ED50 and ED90 of AMS were 0.61 and 3.43 mg/kg/day respectively. I50 and I90 after 20 cycles of artemether selection pressure were 19.67 and 21.45, respectively; 5DFP values were 39.16 and 15.27, respectively; 3-month CP values were 29.36 and 10.79, respectively; and DFSP values were 31.34 and 12.29, respectively. The mean parasitaemia value of AMR (24.70% ± 3.60) relative to AMS (37.66% ± 3.68) at Day 7 post infection after DFSPs revealed a fitness cost of 34.41%. A moderately stable AMRP. berghei line was generated. Known and unknown mutations may be involved in modulating artemether resistance, and therefore molecular investigations are recommended.

Amodiaquine drug pressure selects nonsynonymous mutations in pantothenate kinase 1, diacylglycerol kinase, and phosphatidylinositol-4 kinase in Plasmodium berghei ANKA

Background Lumefantrine (LM), piperaquine (PQ), and amodiaquine (AQ), the long-acting components of the artemisinin-based combination therapies (ACTs), are a cornerstone of malaria treatment in Africa. Studies have shown that PQ, AQ, and LM resistance may arise independently of predicted modes of action. Protein kinases have emerged as mediators of drug action and efficacy in malaria parasites; however, the link between top druggable Plasmodium kinases with LM, PQ, and AQ resistance remains unclear. Using LM, PQ, or AQ-resistant Plasmodium berghei parasites, we have evaluated the association of choline kinase (CK), pantothenate kinase 1 (PANK1), diacylglycerol kinase (DAGK), and phosphatidylinositol-4 kinase (PI4Kβ), and calcium-dependent protein kinase 1 (CDPK1) with LM, PQ, and AQ resistance in Plasmodium berghei ANKA. Methods We used in silico bioinformatics tools to identify ligand-binding motifs, active sites, and sequence conservation across the different parasites. We then used PCR and sequencing analysis to probe for single nucleotide polymorphisms (SNPs) within the predicted functional motifs in the CK, PANK1, DAGK, PI4Kβ, and CDPK1. Using qPCR analysis, we measured the mRNA amount of PANK1, DAGK, and PI4Kβ at trophozoites and schizonts stages. Results We reveal sequence conservation and unique ligand-binding motifs in the CK, PANK1, DAGK, PI4Kβ, and CDPK1 across malaria species. DAGK, PANK1, and PI4Kβ possessed nonsynonymous mutations; surprisingly, the mutations only occurred in the AQr parasites. PANK1 acquired Asn394His, while DAGK contained K270R and K292R mutations. PI4Kβ had Asp366Asn, Ser1367Arg, Tyr1394Asn and Asp1423Asn. We show downregulation of PANK1, DAGK, and PI4Kβ in the trophozoites but upregulation at the schizonts stages in the AQr parasites. Conclusions The selective acquisition of the mutations and the differential gene expression in AQ-resistant parasites may signify proteins under AQ pressure. The role of the mutations in the resistant parasites and their impact on drug responses require investigations using reverse genetics techniques in malaria parasites.

Impact of piperaquine resistance in Plasmodium falciparum on malaria treatment effectiveness in The Guianas: a descriptive epidemiological study

Plasmodium falciparum is an apicomplexan parasite responsible for lethal cases of malaria. According to WHO recommendations, P falciparum cases are treated with artemisinin-based combination therapy including dihydroartemisinin-piperaquine. However, the emergence of resistant parasites against dihydroartemisinin-piperaquine was reported in southeast Asia in 2008 and, a few years later, suspected in South America. To characterise resistance emergence, a treatment efficacy study was performed on the reported patients infected with P falciparum and treated with dihydroartemisinin-piperaquine in French Guiana (n=6, 2016-18). Contemporary isolates collected in French Guiana were genotyped for P falciparum chloroquine resistance transporter (pfCRT; n=845) and pfpm2 and pfpm3 copy number (n=231), phenotyped using the in vitro piperaquine survival assay (n=86), and analysed through genomic studies (n=50). Additional samples from five Amazonian countries and one outside the region were genotyped (n=1440). In field isolates, 40 (47%) of 86 (95% CI 35·9-57·1) were resistant to piperaquine in vitro; these phenotypes were more associated with pfCRTC350R (ie, Cys350Arg) and pfpm2 and pfpm3 amplifications (Dunn test, p<0·001). Those markers were also associated with dihydroartemisinin-piperaquine treatment failure (n=3 [50%] of 6). A high prevalence of piperaquine resistance markers was observed in Suriname in 19 (83%) of 35 isolates and in Guyana in 579 (73%) of 791 isolates. The pfCRTC350R mutation emerged before pfpm2 and pfpm3 amplification in a temporal sequence different from southeast Asia, and in the absence of artemisinin partial resistance, suggesting a geographically distinctive epistatic relationship between these genetic markers. The high prevalence of piperaquine resistance markers in parasite populations of the Guianas, and the risk of associated therapeutic failures calls for caution on dihydroartemisinin-piperaquine use in the region. Furthermore, greater attention should be given to potential differences in genotype to phenotype mapping across genetically distinct parasite populations from different continents. Pan American Health Organization and WHO, French Ministry for Research, European Commission, Santé publique France, Agence Nationale de la Recherche, Fundação de Amparo à Pesquisa do Estado do Amazonas, Ministry of Health of Brazil, Oswaldo Cruz Foundation, and National Institutes of Health. For the French and Portuguese translations of the abstract see Supplementary Materials section.

The first reported case of co-infection of imported hepatitis E and &lt;em&gt;Plasmodium falciparum&lt;/em&gt; malaria in Sri Lanka

Global travel and tourism, especially across tropical countries, may lead to importation of malaria and other infectious diseases into Sri Lanka. This case report describes the first co-infection of imported hepatitis E and Plasmodium falciparum malaria in a tourist diagnosed in Sri Lanka. The patient was initially diagnosed with uncomplicated P. falciparum malaria and was started on treatment with oral Artemisinin-based Combination Therapy (ACT). Deterioration of hepatic enzymes and hyperbilirubinaemia despite the rapid parasitological response to antimalarials led to further investigation and diagnosis of co-infecting hepatitis E in this patient. The importance of clinicians being vigilant on travel associated co-infections is highlighted to ensure early diagnosis and better patient management.

Baseline and recurrent exposure to the standard dose of artemisinin-based combination therapies (ACTs) induces oxidative stress and liver damage in mice (BALB/c)

BackgroundIn malaria-endemic countries, repeated intake of artemisinin-based combination therapies (ACTs) is rampant and driven by drug resistance, improper usage, and easy accessibility. Stress effects and potential liver toxicity due to the frequent therapeutic use of ACTs have not been extensively studied. Here, we investigated the effects of repeated treatment with standard doses of the commonly used ACTs artemether/lumefantrine (A/L) and artesunate-amodiaquine (A/A) on oxidative stress and liver function markers in male mice (BALB/c).MethodsForty Five mice were divided into three groups: control, A/L, and A/A. The drugs were administered three days in a row per week, and the regimen was repeated every two weeks for a total of six cycles. The levels of oxidative stress and liver function markers were measured in both plasma and liver tissue after initial (baseline) and repeated exposures for the second, third, and sixth cycles.ResultsExposure to A/L or A/A caused a significant (p < 0.001) increase in plasma malondialdehyde (MDA) levels after the first and repeated exposure periods. However, Hepatic MDA levels increased significantly (p < 0.01) only after the sixth exposure to A/A. Following either single or repeated exposure to A/L or A/A, plasma and liver glutathione peroxidase (GPx) and catalase (CAT) activities, plasma aspartate and alanine transaminase, alkaline phosphatase activity, and bilirubin levels increased, whereas total plasma protein levels decreased significantly (p < 0.001). Varying degrees of hepatocyte degeneration and blood vessel congestion were observed in liver tissues after a single or repeated treatment period.ConclusionIrrespective of single or repeated exposure to therapeutic doses of A/L or A/A, plasma oxidative stress and liver damage were observed. However, long-term repeated A/A exposure can led to hepatic stress. Compensatory processes involving GPx and CAT activities may help reduce the observed stress.

Variation in neutrophil levels and artemisinin-based combination therapy efficacy in West-Africa.

Polymorphonuclear neutrophils (PMN) are involved in pathogen clearance by phagocytosis. However, the role of PMNs in the efficacy of artemisinin-based combination therapy (ACT) is poorly understood. In a prospective longitudinal in vivo study, neutrophil rates were compared with malaria carriage after treatment with different ACTs: Artemether - lumefantrine (AL), Artesunate - amodiaquine (ASAQ), Dihydroartemisinin - piperaquine (DP) or Pyronaridine artesunate (PA). The study cases were classified as having neutropenia, normal neutrophil levels or neutrophilia depending on the level of neutrophils in the blood. This study included 3148 patients and was analyzed using R. On day 7, only four patients in the neutropenia group and treated with AL had a malaria positive blood smear based on microscopy. On day 28, the rate of recurrent parasitemia in the AL arm was significantly higher in neutropenia patients (50.9%) than in patients with normal rates of neutrophils (43.1%) or in those with neutrophilia (6.0%) (p < 0.001). In ASAQ arm, the rate of recurrent Plasmodium falciparum parasitemia was 58.8% in the neutropenia group versus 29.4% in patients with normal rates of neutrophils and 11.8% in patients with neutrophilia (p < 0.001). No patient treated with DP with normal neutrophil counts or neutrophilia was carrying malaria parasites on day 28. Among the 15 patients with parasitemia on day 28 in the PA arm, 11 (73.33%) had neutropenia while 4 (26.67%) had a normal neutrophil count (p < 0.001). Patients with neutropenia had higher rates of recurrent P. falciparum parasitemia after ACT.

Reporting the impact of artemisinin resistance: Molecular surveillance of pfK13 and pfEXO mutations in Plasmodium falciparum in Southern provinces of Vietnam

Background: Malaria, mainly caused by Plasmodium falciparum, is a major global health concern. In Vietnam, resistance to artemisinin-based combination therapies (ACTs) is rising, jeopardizing malaria control efforts. This study focuses on mutations in the pfK13 and pfEXO genes, particularly the E415G mutation, in Southern Vietnam.&#x0D; Methods: The study involved 421 patients across two cohorts. The first, with 63 patients from Binh Phuoc and Dak Nong, had uncomplicated P. falciparum malaria and were part of the Therapeutic Efficacy Studies (TES), treated according to WHO guidelines (2009). The second cohort, comprising 358 patients from the Central Highlands, aimed to assess mutation frequency in genes linked to artemisinin resistance. Molecular marker analysis, including Sanger sequencing for pfK13 and ARMS-PCR for E415G in pfEXO, was conducted. The study also examined the association of these mutations with Day 3 parasitemia and treatment outcomes using Dihydroartemisinin-Piperaquine (DHA-PPQ).&#x0D; Results: Most cases showed mutations in pfK13, linked to delayed parasite clearance and higher treatment failure, indicating pfK13 as a key marker for artemisinin resistance. The E415G mutation in pfEXO was common but not significantly associated with resistance or treatment outcomes, though there was a tendency towards increased treatment failure among these patients. Conclusion: Our study implies the critical role of the C580Y mutation in the pfK13 gene in artemisinin resistance and its impact on the efficacy of ACTs in Vietnam. The findings highlight the necessity for monitoring these mutations as molecular markers for drug resistance and call for the exploration of alternative treatment strategies in the face of evolving antimalarial drug resistance. This study contributes valuable insights to the molecular epidemiology of malaria in Southern provinces in Vietnam and emphasizes the urgency of addressing artemisinin resistance in the global fight against malaria.&#x0D; Key words: pfK13, E415G , artemisinin resistance, P. falciparum, malaria.

Molecular characterization of the Plasmodium falciparum k13 gene helix domain in samples from native communities of Condorcanqui, Amazonas, Perú

Introduction. Resistance of Plasmodium falciparum to different antimalarial drugs is an obstacle to disease elimination. The artemisinin-resistant genotype of P. falciparum can be assessed by examining polymorphisms in the helix domain of the Pfk13 gene. The World Health Organization recommends these mutations as molecular markers to detect artemisinin-resistant in countries where P. falciparum malaria is endemic. Objective. To identify artemisinin resistance-related mutations present in the helix domain of the P. falciparum k13 gene. Materials and methods. We collected a total of 51 samples through passive case detection, positive for Plasmodium by microscopy, from six communities in the district of Río Santiago in Condorcanqui, Amazonas. Molecular species confirmation was performed by real-time PCR and Pfk13 helix domain was amplified and sequenced by capillary electrophoresis. The obtained sequences were compared with the wild type 3D7 reference strain. Results. A total of 51 positive samples were confirmed for P. falciparum from the communities of Ayambis, Chapiza, Palometa, Muchinguis, Alianza Progreso and Caterpiza. DNA sequences alignment showed the absence of resistance-associated mutations in the k13 gene of the collected samples. Discussion. The obtained results are consistent with similar studies conducted in other South American countries, including Perú, so these data provide a baseline for artemisinin-resistance molecular surveillance in the Amazon region and reinforce the efficacy of artemisinin-based combination therapy in this area.

Increasing Prevalence of Artemisinin-Resistant HRP2-Negative Malaria in Eritrea

BackgroundAlthough the clinical efficacy of antimalarial artemisinin-based combination therapies in Africa remains high, the recent emergence of partial resistance to artemisinin in Plasmodium falciparum on the continent is troubling, given the lack of alternative treatments.MethodsIn this study, we used data from drug-efficacy studies conducted between 2016 and 2019 that evaluated 3-day courses of artemisinin-based combination therapy (artesunate–amodiaquine or artemether–lumefantrine) for uncomplicated malaria in Eritrea to estimate the percentage of patients with day-3 positivity (i.e., persistent P. falciparum parasitemia 3 days after the initiation of therapy). We also assayed parasites for mutations in Pfkelch13 as predictive markers of partial resistance to artemisinin and screened for deletions in hrp2 and hrp3 that result in variable performance of histidine rich protein 2 (HRP2)–based rapid diagnostic tests for malaria.ResultsWe noted an increase in the percentage of patients with day-3 positivity from 0.4% (1 of 273) in 2016 to 1.9% (4 of 209) in 2017 and 4.2% (15 of 359) in 2019. An increase was also noted in the prevalence of the Pfkelch13 R622I mutation, which was detected in 109 of 818 isolates before treatment, from 8.6% (24 of 278) in 2016 to 21.0% (69 of 329) in 2019. The odds of day-3 positivity increased by a factor of 6.2 (95% confidence interval, 2.5 to 15.5) among the patients with Pfkelch13 622I variant parasites. Partial resistance to artemisinin, as defined by the World Health Organization, was observed in Eritrea. More than 5% of the patients younger than 15 years of age with day-3 positivity also had parasites that carried Pfkelch13 R622I. In vitro, the R622I mutation conferred a low level of resistance to artemisinin when edited into NF54 and Dd2 parasite lines. Deletions in both hrp2 and hrp3 were identified in 16.9% of the parasites that carried the Pfkelch13 R622I mutation, which made them potentially undetectable by HRP2-based rapid diagnostic tests.ConclusionsThe emergence and spread of P. falciparum lineages with both Pfkelch13-mediated partial resistance to artemisinin and deletions in hrp2 and hrp3 in Eritrea threaten to compromise regional malaria control and elimination campaigns. (Funded by the Bill and Melinda Gates Foundation and others; Australian New Zealand Clinical Trials Registry numbers, ACTRN12618001223224, ACTRN12618000353291, and ACTRN12619000859189.)

Determine the enzymatic kinetic characteristics of CYP3A4 variants utilizing artemether-lumefantrine

Artemether-lumefantrine is an artemisinin-based combination therapy for the treatment of malaria, which are primarily metabolized by cytochrome P450 3A4. Therapeutic difference caused by gene polymorphisms of CYP3A4 may lead to uncertain adverse side effects or treatment failure. The aim of this study was to evaluate the effect of CYP3A4 gene polymorphism on artemether-lumefantrine metabolism in vitro. Enzyme kinetics assay was performed using recombinant human CYP3A4 cell microsomes. The analytes, dihydroartimisinin and desbutyl-lumefantrine, were detected by ultra-performance liquid chromatography tandem mass spectrometry. The results demonstrated that compared to CYP3A4.1, the intrinsic clearance of CYP3A4.4, 5, 9, 16, 18, 23, 24, 28, 31–34 significantly reduced for artemether (58.5%–93.3%), and CYP3A4.17 almost loss catalytic activity. Simultaneously, CYP3A4.5, 14, 17, 24 for lumefantrine were decreased by 56.1%–99.6%, and CYP3A4.11, 15, 18, 19, 23, 28, 29, 31–34 for lumefantrine was increased by 51.7%–296%. The variation in clearance rate indicated by molecular docking could be attributed to the disparity in the binding affinity of artemether and lumefantrine with CYP3A4. The data presented here have enriched our understanding of the effect of CYP3A4 gene polymorphism on artemether-lumefantrine metabolizing. These findings serve as a valuable reference and provide insights for guiding the treatment strategy involving artemether-lumefantrine.

Effect of primaquine dose on the risk of recurrence in patients with uncomplicated Plasmodium vivax: a systematic review and individual patient data meta-analysis

Primaquine is used to eliminate Plasmodium vivax hypnozoites, but its optimal dosing regimen remains unclear. We undertook a systematic review and individual patient data meta-analysis to investigate the efficacy and tolerability of different primaquine dosing regimens to prevent P vivax recurrence. For this systematic review and individual patient data meta-analysis, we searched MEDLINE, Web of Science, Embase, and Cochrane Central for prospective clinical studies of uncomplicated P vivax from endemic countries published between Jan 1, 2000, and June 8, 2023. We included studies if they had active follow-up of at least 28 days, and if they included a treatment group with daily primaquine given over multiple days, where primaquine was commenced within 7 days of schizontocidal treatment and was given alone or coadministered with chloroquine or one of four artemisinin-based combination therapies (ie, artemether-lumefantrine, artesunate-mefloquine, artesunate-amodiaquine, or dihydroartemisinin-piperaquine). We excluded studies if they were on prevention, prophylaxis, or patients with severe malaria, or if data were extracted retrospectively from medical records outside of a planned trial. For the meta-analysis, we contacted the investigators of eligible trials to request individual patient data and we then pooled data that were made available by Aug 23, 2021. We assessed the effects of total dose and duration of primaquine regimens on the rate of first P vivax recurrence between day 7 and day 180 by Cox's proportional hazards regression (efficacy analysis). The effect of primaquine daily dose on gastrointestinal symptoms on days 5-7 was assessed by modified Poisson regression (tolerability analysis). The study was registered with PROSPERO, CRD42019154470. Of 226 identified studies, 23 studies with patient-level data from 6879 patients from 16 countries were included in the efficacy analysis. At day 180, the risk of recurrence was 51·0% (95% CI 48·2-53·9) in 1470 patients treated without primaquine, 19·3% (16·9-21·9) in 2569 patients treated with a low total dose of primaquine (approximately 3·5 mg/kg), and 8·1% (7·0-9·4) in 2811 patients treated with a high total dose of primaquine (approximately 7 mg/kg), regardless of primaquine treatment duration. Compared with treatment without primaquine, the rate of P vivax recurrence was lower after treatment with low-dose primaquine (adjusted hazard ratio 0·21, 95% CI 0·17-0·27; p<0·0001) and high-dose primaquine (0·10, 0·08-0·12; p<0·0001). High-dose primaquine had greater efficacy than low-dose primaquine in regions with high and low relapse periodicity (ie, the time from initial infection to vivax relapse). 16 studies with patient-level data from 5609 patients from ten countries were included in the tolerability analysis. Gastrointestinal symptoms on days 5-7 were reported by 4·0% (95% CI 0·0-8·7) of 893 patients treated without primaquine, 6·2% (0·5-12·0) of 737 patients treated with a low daily dose of primaquine (approximately 0·25 mg/kg per day), 5·9% (1·8-10·1) of 1123 patients treated with an intermediate daily dose (approximately 0·5 mg/kg per day) and 10·9% (5·7-16·1) of 1178 patients treated with a high daily dose (approximately 1 mg/kg per day). 20 of 23 studies included in the efficacy analysis and 15 of 16 in the tolerability analysis had a low or unclear risk of bias. Increasing the total dose of primaquine from 3·5 mg/kg to 7 mg/kg can reduce P vivax recurrences by more than 50% in most endemic regions, with a small associated increase in gastrointestinal symptoms. Australian National Health and Medical Research Council, Bill & Melinda Gates Foundation, and Medicines for Malaria Venture.

Primaquine dose and the risk of haemolysis in patients with uncomplicated Plasmodium vivax malaria: a systematic review and individual patient data meta-analysis

Primaquine radical cure is used to treat dormant liver-stage parasites and prevent relapsing Plasmodium vivax malaria but is limited by concerns of haemolysis. We undertook a systematic review and individual patient data meta-analysis to investigate the haematological safety of different primaquine regimens for P vivax radical cure. For this systematic review and individual patient data meta-analysis, we searched MEDLINE, Web of Science, Embase, and Cochrane Central for prospective clinical studies of uncomplicated P vivax from endemic countries published between Jan 1, 2000, and June 8, 2023. We included studies if they had active follow-up of at least 28 days, if they included a treatment group with daily primaquine given over multiple days where primaquine was commenced within 3 days of schizontocidal treatment and was given alone or coadministered with chloroquine or one of four artemisinin-based combination therapies (ie, artemether-lumefantrine, artesunate-mefloquine, artesunate-amodiaquine, or dihydroartemisinin-piperaquine), and if they recorded haemoglobin or haematocrit concentrations on day 0. We excluded studies if they were on prevention, prophylaxis, or patients with severe malaria, or if data were extracted retrospectively from medical records outside of a planned trial. For the meta-analysis, we contacted the investigators of eligible trials to request individual patient data and we then pooled data that were made available by Aug 23, 2021. The main outcome was haemoglobin reduction of more than 25% to a concentration of less than 7 g/dL by day 14. Haemoglobin concentration changes between day 0 and days 2-3 and between day 0 and days 5-7 were assessed by mixed-effects linear regression for patients with glucose-6-phosphate dehydrogenase (G6PD) activity of (1) 30% or higher and (2) between 30% and less than 70%. The study was registered with PROSPERO, CRD42019154470 and CRD42022303680. Of 226 identified studies, 18 studies with patient-level data from 5462 patients from 15 countries were included in the analysis. A haemoglobin reduction of more than 25% to a concentration of less than 7 g/dL occurred in one (0·1%) of 1208 patients treated without primaquine, none of 893 patients treated with a low daily dose of primaquine (<0·375 mg/kg per day), five (0·3%) of 1464 patients treated with an intermediate daily dose (0·375 mg/kg per day to <0·75 mg/kg per day), and six (0·5%) of 1269 patients treated with a high daily dose (≥0·75 mg/kg per day). The covariate-adjusted mean estimated haemoglobin changes at days 2-3 were -0·6 g/dL (95% CI -0·7 to -0·5), -0·7 g/dL (-0·8 to -0·5), -0·6 g/dL (-0·7 to -0·4), and -0·5 g/dL (-0·7 to -0·4), respectively. In 51 patients with G6PD activity between 30% and less than 70%, the adjusted mean haemoglobin concentration on days 2-3 decreased as G6PD activity decreased; two patients in this group who were treated with a high daily dose of primaquine had a reduction of more than 25% to a concentration of less than 7 g/dL. 17 of 18 included studies had a low or unclear risk of bias. Treatment of patients with G6PD activity of 30% or higher with 0·25-0·5 mg/kg per day primaquine regimens and patients with G6PD activity of 70% or higher with 0·25-1 mg/kg per day regimens were associated with similar risks of haemolysis to those in patients treated without primaquine, supporting the safe use of primaquine radical cure at these doses. Australian National Health and Medical Research Council, Bill & Melinda Gates Foundation, and Medicines for Malaria Venture.

Threshold dynamics and regional optimal control of a malaria model with spatial heterogeneity and ivermectin therapy

The recent experimental results illustrate that adding ivermectin to artemisinin-based combination therapy can target malaria parasite and its vector, which may be a new treatment option. In this paper, we present a new malaria transmission model, which incorporates spatial heterogeneity, general incidence rate and treatment plan with ivermectin. The basic reproduction number R0 is introduced as a threshold parameter to determine whether malaria will eventually die out or not. Further, we propose and analyze the regional optimal control problem to minimize mosquito population, exposed and infectious humans as well as cost. Numerically, we investigate the transmission and control of malaria in The Gambia. Results show that the treatment plans with ivermectin and without ivermectin have the same contribution to R0, but have different effects on the epidemic level of malaria. This conclusion also holds for different incidence rates with some assumptions. Moreover, by comparing the cost and benefit of different strategies, the most cost-effective strategy is found.

The temporal dynamics of Plasmodium species infection after artemisinin-based combination therapy (ACT) among asymptomatic children in the Hohoe municipality, Ghana

BackgroundThe routine surveillance of asymptomatic malaria using nucleic acid-based amplification tests is essential in obtaining reliable data that would inform malaria policy formulation and the implementation of appropriate control measures.MethodsIn this study, the prevalence rate and the dynamics of Plasmodium species among asymptomatic children (n = 1697) under 5 years from 30 communities within the Hohoe municipality in Ghana were determined.Results and discussionThe observed prevalence of Plasmodium parasite infection by polymerase chain reaction (PCR) was 33.6% (571/1697), which was significantly higher compared to that obtained by microscopy [26.6% (451/1697)] (P < 0.0001). Based on species-specific analysis by nested PCR, Plasmodium falciparum infection [33.6% (570/1697)] was dominant, with Plasmodium malariae, Plasmodium ovale and Plasmodium vivax infections accounting for 0.1% (1/1697), 0.0% (0/1697), and 0.0% (0/1697), respectively. The prevalence of P. falciparum infection among the 30 communities ranged from 0.0 to 82.5%. Following artesunate-amodiaquine (AS + AQ, 25 mg/kg) treatment of a sub-population of the participants (n = 184), there was a substantial reduction in Plasmodium parasite prevalence by 100% and 79.2% on day 7 based on microscopy and nested PCR analysis, respectively. However, there was an increase in parasite prevalence from day 14 to day 42, with a subsequent decline on day 70 by both microscopy and nested PCR. For parasite clearance rate analysis, we found a significant proportion of the participants harbouring residual Plasmodium parasites or parasite genomic DNA on day 1 [65.0% (13/20)], day 2 [65.0% (13/20)] and day 3 [60.0% (12/20)] after initiating treatment. Of note, gametocyte carriage among participants was low before and after treatment.ConclusionTaken together, the results indicate that a significant number of individuals could harbour residual Plasmodium parasites or parasite genomic DNA after treatment. The study demonstrates the importance of routine surveillance of asymptomatic malaria using sensitive nucleic acid-based amplification techniques.

Lumefantrine pressure selects nonsynonymous mutation in cysteine desulfurase IscS gene in the rodent malaria parasite Plasmodium berghei ANKA

Background: Lumefantrine (LM), piperaquine (PQ), and amodiaquine (AQ) are the essential long-acting partner drugs in the artemisinin-based combination therapies (ACTs) treatment regimens globally. The recent report on the emergence of artemisinin-resistant parasites portends an imminent failure of the partner drug in clearing the high residual parasite densities. Understanding the resistance mechanisms to partner drugs remains critical for tracking resistant parasites. Cysteine desulfurase IscS (nfs1), one of the proteins involved in the iron-sulfur (FeS) biogenesis pathway, has been implicated in mediating malaria parasite drug resistance. Methods: Using the rodent malaria parasites Plasmodium berghei ANKA in mice, we assessed whether the nfs1 gene is associated with LM, PQ, and AQ resistance. We first verified the stability of the LM, PQ, and AQ-resistant parasites in the standard 4-Day Suppressive Test. By means of PCR and sequencing analysis, we probed for single nucleotide polymorphisms (SNPs) in the nfs1 gene. Using qPCR, we then measured the expression of the nfs1 gene in resistant parasites relative to the drug-sensitive parent parasites. Results: Our analyses of nfs1 reveal a non-synonymous Gln142Arg mutation in the LM and PQ-resistant parasites. This mutation was not detected in the AQ-resistant parasites. The mRNA quantification of the nfs1 gene reveals differential expression in both LM and PQ-resistant parasites. Conversely, nfs1 expression remained unchanged in the AQ-resistant parasites. Conclusion: Our data suggest that LM and PQ selection pressure induces nonsynonymous mutation and differential expression of the nfs1 gene in Plasmodium berghei. Collectively, these findings provide a premise for investigating LM and PQ resistance mechanisms in both P. berghei and P. falciparum.

Healthcare provider and drug dispenser knowledge and adherence to guidelines for the case management of malaria in pregnancy in the context of multiple first-line artemisinin-based combination therapy in western Kenya

BackgroundConcerns about emerging resistance to artemether-lumefantrine (AL) in Africa prompted the pilot introduction of multiple first-line therapies (MFT) in Western Kenya, potentially exposing women-of-childbearing-age (WOCBA) to anti-malarials with unknown safety profiles in the first trimester. The study assessed healthcare provider knowledge and adherence to national guidelines for managing malaria in pregnancy in the context of the MFT pilot.MethodsFrom March to April 2022, a cross-sectional study was conducted in 50 health facilities (HF) and 40 drug outlets (DO) using structured questionnaires to assess pregnancy detection, malaria diagnosis, and treatment choices by trimester. Differences between HF and DO providers and between MFT and non-MFT HFs were assessed using Chi-square tests.ResultsOf 174 providers (77% HF, 23% DO), 56% were from MFT pilot facilities. Most providers had tertiary education; 5% HF and 20% DO had only primary or secondary education. More HF than DO providers had knowledge of malaria treatment guidelines (62% vs. 40%, p = 0.023), received training in malaria in pregnancy (49% vs. 20%, p = 0.002), and reported assessing for pregnancy in WOCBA (98% vs. 78%, p < 0.001). Most providers insisted on parasitological diagnosis, with 59% HF using microscopy and 85% DO using rapid diagnostic tests. More HF than DO providers could correctly name the drugs for treating uncomplicated malaria in the first trimester (oral quinine, or AL if quinine is unavailable) (90% vs. 58%, p < 0.001), second and third trimesters (artemisinin-based combination therapy) (84% vs. 70%, p = 0.07), and for severe malaria (parenteral artesunate/artemether) (94% vs. 60%, p < 0.001). Among HF providers, those in the MFT pilot had more knowledge of malaria treatment guidelines (67% vs. 49%, p = 0.08) and had received training on treatment of malaria in pregnancy (56% vs. 32%, p = 0.03). Few providers (10% HF and 12% DO) had adequate knowledge of malaria treatment in pregnancy, defined as the correct drug and dose for uncomplicated and severe malaria in all trimesters.ConclusionsKnowledge of national malaria in pregnancy treatment guidelines among providers in Western Kenya is suboptimal. Robust training on appropriate anti-malarial and dosage is needed, particularly given the recent change in recommendation for artemether-lumefantrine use in the first trimester. Supervision of DO and HF practices is essential for correct treatment of malaria in pregnancy in the context of MFT programmes.

Strategies for deploying triple artemisinin-based combination therapy in the Greater Mekong Subregion

BackgroundThis is a qualitative study to identify implementation challenges for deploying triple artemisinin-based combination therapy (TACT) in the Greater Mekong Subregion (GMS) of Southeast Asia and to explore strategies to overcome these challenges.MethodsIn-depth interviews were conducted in three countries that have repeatedly been confronted with ACT failures: Cambodia, Vietnam, and Lao PDR. Thirty-nine key stakeholders in the healthcare systems in these countries were interviewed. One participatory workshop was conducted in Cambodia, where scenarios for potential TACT deployment were discussed.ResultsThe results section is organized around four strategic themes that emerged from the data: policy support, data and evidence, logistics and operation, and downstream engagement. The study revealed that countries in the GMS currently rely on ACT to eliminate Plasmodium falciparum malaria by 2025. TACT is, however, considered to be a useful backup strategy in case of future treatment failures and to prevent the re-establishment of malaria. The study showed that a major challenge ahead is to engage decision makers and healthcare providers into deploying TACT, given the low case incidence of falciparum malaria in the GMS. Interview respondents were also skeptical whether healthcare providers would be willing to engage in new therapies for a disease they hardly encounter anymore. Hence, elaborate information dissemination strategies were considered appropriate and these strategies should especially target village malaria workers. Respondents proposed several regulatory and programmatic strategies to anticipate the formation of TACT markets in the GMS. These strategies include early dossier submission to streamline regulatory procedures, early stakeholder engagement strategies to shorten implementation timelines, and inclusion of TACT as second-line therapy to accelerate their introduction in case they are urgently needed.ConclusionsThis paper presents a qualitative study to identify implementation challenges for deploying TACT in the GMS and to explore strategies to overcome these challenges. The findings could benefit researchers and decision makers in strategizing towards potential future deployment of TACT in the GMS to combat artemisinin and partner drug resistance.