Multicentric assessment of the efficacy and tolerability of dihydroartemisinin-piperaquine compared to artemether-lumefantrine in the treatment of uncomplicated Plasmodium falciparum malaria in sub-Saharan Africa

Haematological consequences of acute uncomplicated falciparum malaria: a WorldWide Antimalarial Resistance Network pooled analysis of individual patient data

BACKGROUND

Plasmodium falciparum malaria is associated with anaemia-related morbidity, attributable to host, parasite and drug factors. We quantified the haematological response following treatment of uncomplicated P. falciparum malaria to identify the factors associated with malarial anaemia.

METHODS

Individual patient data from eligible antimalarial efficacy studies of uncomplicated P. falciparum malaria, available through the WorldWide Antimalarial Resistance Network data repository prior to August 2015, were pooled using standardised methodology. The haematological response over time was quantified using a multivariable linear mixed effects model with nonlinear terms for time, and the model was then used to estimate the mean haemoglobin at day of nadir and day 7. Multivariable logistic regression quantified risk factors for moderately severe anaemia (haemoglobin < 7 g/dL) at day 0, day 3 and day 7 as well as a fractional fall ≥ 25% at day 3 and day 7.

RESULTS

A total of 70,226 patients, recruited into 200 studies between 1991 and 2013, were included in the analysis: 50,859 (72.4%) enrolled in Africa, 18,451 (26.3%) in Asia and 916 (1.3%) in South America. The median haemoglobin concentration at presentation was 9.9 g/dL (range 5.0-19.7 g/dL) in Africa, 11.6 g/dL (range 5.0-20.0 g/dL) in Asia and 12.3 g/dL (range 6.9-17.9 g/dL) in South America. Moderately severe anaemia (Hb < 7g/dl) was present in 8.4% (4284/50,859) of patients from Africa, 3.3% (606/18,451) from Asia and 0.1% (1/916) from South America. The nadir haemoglobin occurred on day 2 post treatment with a mean fall from baseline of 0.57 g/dL in Africa and 1.13 g/dL in Asia. Independent risk factors for moderately severe anaemia on day 7, in both Africa and Asia, included moderately severe anaemia at baseline (adjusted odds ratio (AOR) = 16.10 and AOR = 23.00, respectively), young age (age < 1 compared to ≥ 12 years AOR = 12.81 and AOR = 6.79, respectively), high parasitaemia (AOR = 1.78 and AOR = 1.58, respectively) and delayed parasite clearance (AOR = 2.44 and AOR = 2.59, respectively). In Asia, patients treated with an artemisinin-based regimen were at significantly greater risk of moderately severe anaemia on day 7 compared to those treated with a non-artemisinin-based regimen (AOR = 2.06 [95%CI 1.39-3.05], p < 0.001).

CONCLUSIONS

In patients with uncomplicated P. falciparum malaria, the nadir haemoglobin occurs 2 days after starting treatment. Although artemisinin-based treatments increase the rate of parasite clearance, in Asia they are associated with a greater risk of anaemia during recovery.

Safety of dihydroartemisinin-piperaquine versus artemether-lumefantrine for the treatment of uncomplicated Plasmodium falciparum malaria among children in Africa: a systematic review and meta-analysis of randomized control trials

BACKGROUND

The efficacies of artemisinin based combinations have been excellent in Africa, but also comprehensive evidence regarding their safety would be important. The aim of this review was to synthesize available evidence on the safety of dihydroartemisinin-piperaquine (DHA-PQ) compared to artemether-lumefantrine (AL) for the treatment of uncomplicated Plasmodium falciparum malaria among children in Africa.

METHODS

A systematic literature search was done to identify relevant articles from online databases PubMed/ MEDLINE, Embase, and Cochrane Center for Clinical Trial database (CENTRAL) for retrieving randomized control trials comparing safety of DHA-PQ and AL for treatment of uncomplicated P. falciparum malaria among children in Africa. The search was performed from August 2020 to 30 April 2021. Using Rev-Man software (V5.4.1), the extracted data from eligible studies were pooled as risk ratio (RR) with 95% confidence interval (CI).

RESULTS

In this review, 18 studies were included, which involved 10,498 participants were included. Compared to AL, DHA-PQ was associated with a slightly higher frequency of early vomiting (RR 2.26, 95% CI 1.46 to 3.50; participants = 7796; studies = 10; I2 = 0%, high quality of evidence), cough (RR 1.06, 95% CI 1.01 to 1.11; participants = 8013; studies = 13; I2 = 0%, high quality of evidence), and diarrhoea (RR 1.16, 95% CI 1.03 to 1.31; participants = 6841; studies = 11; I2 = 8%, high quality of evidence) were more frequent in DHA-PQ treatment arm.

CONCLUSION

From this review, it can be concluded that early vomiting, diarrhoea, and cough were common were significantly more frequent in patients who were treated with the DHA-PQ than that of AL, and both drugs are well tolerated. More studies comparing AL with DHA-PQ are needed to determine the comparative safety of these drugs.

Comparative effect of dihydroartemisinin-piperaquine and artemether-lumefantrine on gametocyte clearance and haemoglobin recovery in children with uncomplicated Plasmodium falciparum malaria in Africa: a systematic review and meta-analysis of randomized control trials

BACKGROUND

Plasmodium falciparum gametocytaemia has been associated with anaemia. The aim of this review was to synthesize available evidence on the comparative effect of dihydroartemisinin-piperaquine (DHA-PQ) and artemether-lumefantrine (AL) on gametocyte clearance and haemoglobin recovery in children with uncomplicated P. falciparum malaria in Africa.

METHODS

A systematic literature search was undertaken to identify relevant articles from online databases. The search was performed from August 2020 to 30 April 2021. Extracted data from eligible studies were pooled as risk ratios with 95% confidence intervals (CI).

RESULTS

Gametocyte carriage was reduced in both treatment groups, with no significant difference found between the groups. However, on days 28 and 42, a significant increase in serum haemoglobin level from baseline was observed in the DHA-PQ group (standardized mean difference 0.15, 95% CI 0.05-0.26; participants=2715; studies=4; I²⁼32%, high quality of evidence) compared with the AL group (mean difference 0.35, 95% CI 0.12-0.59; participants=1434; studies=3; I²=35%, high quality of evidence).

CONCLUSION

DHA-PQ had a greater impact on haemoglobin recovery than AL on days 28 and 42; this difference was significant.

Efficacy and safety of dihydroartemisinin-piperaquine versus artemether-lumefantrine for treatment of uncomplicated Plasmodium falciparum malaria in Ugandan children: a systematic review and meta-analysis of randomized control trials

Background

The emergence of artemisinin resistance in Southeast Asia and Plasmodium falciparum kelch13 propeller gene mutations in sub-Saharan African pose the greatest threat to global efforts to control malaria. This is a critical concern in Uganda, where artemisinin-based combination therapy (ACT) is the first-line treatment for uncomplicated falciparum. The objective of this study was to compare the efficacy and safety of dihydroartemisinin–piperaquine (DHA–PQ) and artemether–lumefantrine (AL) for the treatment of uncomplicated falciparum malaria in Ugandan children.

Methods

A search of PubMed and the Cochrane Central Register of Controlled Trials for retrieving randomized controlled trials comparing the efficacy and safety of DHA–PQ and AL for treatment of uncomplicated falciparum malaria in Ugandan children was done. The search was performed up to 31 August 2020. The data extracted from eligible studies and pooled as risk ratio (RR) with a 95% confidence interval (CI), using Rev Man Software (5.4). The protocol was registered in PROSPERO, ID: CRD42020182354.

Results

Eleven trials were included in this review and two of them only included under safety outcome. Total 3798 participants were enrolled. The PCR unadjusted treatment failure was significantly lower with DHA–PQ at day 28 (RR 0.30, 95% CI 0.19–0.49; participants = 7863; studies = 5; I² = 93%, low quality evidence) and at day 42 (RR 0.53, 95% CI 0.38–0.76; participants = 1618; studies = 4; I² = 79%, moderate quality of evidence). The PCR adjusted treatment failure at day 42 was significantly lower with DHA–PQ treatment group (RR 0.45, 95% CI 0.28 to 0.72; participants = 1370; studies = 5, high quality of evidence), and it was below 5% in both arms at day 28 (moderate quality of evidence). AL showed a longer prophylactic effect on new infections which may last for up to 63 days (PCR-adjusted treatment failure: RR 2.04, 95% CI 1.13–3.70; participants = 1311; studies = 2, moderate quality of evidence). Compared to AL, DHA–PQ was associated with a slightly higher frequency of cough (RR 1.07, 95% CI 1.01 to 1.13; 2575 participants; six studies; high quality of evidence). In both treatment groups, the risk of recurrent parasitaemia due to possible recrudescence was less than 5% at day 28. The appearance of gametocyte between 29 and 42 days was also significantly lower in DHA–PQ than AL (RR 0.26, 95% CI 0.12 to 0.56; participants = 623; studies = 2; I² = 0%).

Conclusion

Compared to AL, DHA–PQ appeared to reduce treatment failure and gametocyte carriage in Ugandan children. This may trigger DHA–PQ to become the first-line treatment option. Both treatments were safe and well-tolerated.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-021-03711-4.

Drug resistance markers within an evolving efficacy of anti-malarial drugs in Cameroon: a systematic review and meta-analysis (1998-2020)

BACKGROUND

Malaria remains highly endemic in Cameroon. The rapid emergence and spread of drug resistance was responsible for the change from monotherapies to artemisinin-based combinations. This systematic review and meta-analysis aimed to determine the prevalence and distribution of Plasmodium falciparum drug resistance markers within an evolving efficacy of anti-malarial drugs in Cameroon from January 1998 to August 2020.

METHODS

The PRISMA-P and PRISMA statements were adopted in the inclusion of studies on single nucleotide polymorphisms (SNPs) of P. falciparum anti-malarial drug resistance genes (Pfcrt, Pfmdr1, Pfdhfr, Pfdhps, Pfatp6, Pfcytb and Pfk13). The heterogeneity of the included studies was evaluated using the Cochran's Q and I2 statistics. The random effects model was used as standard in the determination of heterogeneity between studies.

RESULTS

Out of the 902 records screened, 48 studies were included in this aggregated meta-analysis of molecular data. A total of 18,706 SNPs of the anti-malarial drug resistance genes were genotyped from 47,382 samples which yielded a pooled prevalence of 35.4% (95% CI 29.1-42.3%). Between 1998 and 2020, there was significant decline (P < 0.0001 for all) in key mutants including Pfcrt 76 T (79.9%-43.0%), Pfmdr1 86Y (82.7%-30.5%), Pfdhfr 51I (72.2%-66.9%), Pfdhfr 59R (76.5%-67.8%), Pfdhfr 108 N (80.8%-67.6%). The only exception was Pfdhps 437G which increased over time (30.4%-46.9%, P < 0.0001) and Pfdhps 540E that remained largely unchanged (0.0%-0.4%, P = 0.201). Exploring mutant haplotypes, the study observed a significant increase in the prevalence of Pfcrt CVIET mixed quintuple haplotype from 57.1% in 1998 to 57.9% in 2020 (P < 0.0001). In addition, within the same study period, there was no significant change in the triple Pfdhfr IRN mutant haplotype (66.2% to 67.3%, P = 0.427). The Pfk13 amino acid polymorphisms associated with artemisinin resistance were not detected.

CONCLUSIONS

This review reported an overall decline in the prevalence of P. falciparum gene mutations conferring resistance to 4-aminoquinolines and amino alcohols for a period over two decades. Resistance to artemisinins measured by the presence of SNPs in the Pfk13 gene does not seem to be a problem in Cameroon. Systematic review registration PROSPERO CRD42020162620.

Systematic Review and Pharmacological Considerations for Chloroquine and Its Analogs in the Treatment for COVID-19

COVID-19 has been announced pandemic by WHO and over 17,000,000 people infected (Till April 21st 2020). The disease is currently under control in China, with a curative rate of 86.8%. Chloroquine (CQ) is an old anti-malarial drug with good tolerability, which had proved to be effective in previous SARS-coronavirus, which spread and disappeared between 2002-2003. In vitro studies demonstrated the efficacy of CQ in curing COVID-19. Consequently, via analytical PBPK modeling, a further preliminary clinical trial has proved the efficacy and safety of CQ in China., and multiple clinical trials were registered and approved to investigate the activity of other analogs of CQ against COVID-19. We have listed all the clinical trials and made a meta-analysis of published data of hydroxychloroquine (HCQ). HCQ could increase the CT improvement and adverse reactions (ADRs) significantly though there was considerable heterogeneity among current researches. Actually, CQ and its analogs have unique pharmacokinetic characteristics, which would induce severe side effects in some circumstances. We have then summarized pharmacological considerations for these drugs so as to provide to the busy clinicians to avoid potential side effects when administered CQ or its analogs to COVID-19 patients, especially in the elderly, pediatrics, and pregnancies.

Therapeutic Efficacy of Artemether-Lumefantrine (Coartem®) for the Treatment of Uncomplicated Falciparum Malaria in Africa: A Systematic Review

Background

Africa still bears the largest burden of malaria as the majority of infections in the continent are caused by P. falciparum. Artemether-lumefantrine (AL, Coartem®) is the most widely used artemisinin-based combination therapy (ACT), for treating uncomplicated falciparum malaria globally. However, the development of resistance to antimalarial drugs is a major challenge for malaria control. In this review, the efficacy of AL for the treatment of uncomplicated falciparum malaria in Africa was evaluated.

Methods

Articles published between January 2015 and July 2019 were systematically searched using comprehensive search strings from PubMed/Medline, SCOPUS, and grey literature from Google Scholar. Interventional studies that followed patients for at least 28 days were included. Two reviewers independently assessed study eligibility, extracted data, and assessed risk of bias. All the included articles were measured to be good quality. While computing the efficacy of AL, polymerase chain reaction (PCR)–corrected cure rate (adequate clinical and parasitological response, ACPR) at day 28 was considered as the main endpoint. Meta-analysis was computed using STATA v 15 to calculate the pooled ACPR.

Results

In this review, 39 articles that reported the treatment outcome of 8,320 patients were included. After 28 days of follow-up, the pooled PCR uncorrected and corrected APCR was at 87% (95% CI: 85-90%) and 97.0% (95% CI: 96-98%), respectively. Moreover, the proportion of early treatment failure (ETF) was almost 0%, while most of the included articles reported <8% late treatment failures. The reinfection and recrudescence rate was less than 10% and 2.6%, respectively, within 28 days. We noted rapid fever and parasite clearance in which greater than 93% and 94% patients were parasite and fever free at day three following AL treatment.

Conclusions

This review discovered that despite more than a decade since its introduction, Coartem® remains effective and thus could continue to be the drug of choice for the treatment of uncomplicated falciparum malaria for all age groups in Africa. However, the risk of new emerging resistance for this combination warrants regular monitoring of its efficacy across the continent.

Efficacy and safety of artemisinin-based combination therapy and the implications of Pfkelch13 and Pfcoronin molecular markers in treatment failure in Senegal

In 2006, Senegal adopted artemisinin-based combination therapy (ACT) as first-line treatment in the management of uncomplicated malaria. This study aimed to update the status of antimalarial efficacy more than ten years after their first introduction. This was a randomized, three-arm, open-label study to evaluate the efficacy and safety of artemether-lumefantrine (AL), artesunate-amodiaquine (ASAQ) and dihydroartemisinin-piperaquine (DP) in Senegal. Malaria suspected patients were screened, enrolled, treated, and followed for 28 days for AL and ASAQ arms or 42 days for DP arm. Clinical and parasitological responses were assessed following antimalarial treatment. Genotyping (msp1, msp2 and 24 SNP-based barcode) were done to differentiate recrudescence from re-infection; in case of PCR-confirmed treatment failure, Pfk13 propeller and Pfcoronin genes were sequenced. Data was entered and analyzed using the WHO Excel-based application. A total of 496 patients were enrolled. In Diourbel, PCR non-corrected/corrected adequate clinical and parasitological responses (ACPR) was 100.0% in both the AL and ASAQ arms. In Kedougou, PCR corrected ACPR values were 98.8%, 100% and 97.6% in AL, ASAQ and DP arms respectively. No Pfk13 or Pfcoronin mutations associated with artemisinin resistance were found. This study showed that AL, ASAQ and DP remain efficacious and well-tolerated in the treatment of uncomplicated P. falciparum malaria in Senegal.

Evaluation of residual submicroscopic Plasmodium falciparum parasites 3 days after initiation of treatment with artemisinin-based combination therapy

Plasmodium falciparum resistance against artemisinin has not emerged in Africa; however, there are reports of the presence of polymerase chain reaction-determined residual submicroscopic parasitaemia detected on day 3 after artemisinin-based combination therapy (ACT). These residual submicroscopic parasites are thought to represent tolerant/resistant parasites against artemisinin, the fast-acting component of the combination. This review focused on residual submicroscopic parasitaemia, what it represents, and its significance on the emergence and spread of artemisinin resistance in Africa. Presence of residual submicroscopic parasitemia on day 3 after treatment initiation leaves question on whether successful treatment is attained with ACT. Thus there is a need to determine the potential public health implication of the PCR-determined residual submicroscopic parasitaemia observed on day 3 after ACT. Robust techniques, such as in vitro cultivation, should be used to evaluate if the residual submicroscopic parasites detected on day 3 after ACT are viable asexual parasites, or gametocytes, or the DNA of the dead parasites waiting to be cleared from the circulation. Such techniques would also evaluate the transmissibility of these residual parasites.

Baseline Ex Vivo and Molecular Responses of Plasmodium falciparum Isolates to Piperaquine before Implementation of Dihydroartemisinin-Piperaquine in Senegal

Dihydroartemisinin-piperaquine, which was registered in 2017 in Senegal, is not currently used as the first-line treatment against uncomplicated malaria. A total of 6.6% to 17.1% of P. falciparum isolates collected in Dakar in 2013 to 2015 showed ex vivo-reduced susceptibility to piperaquine. Neither the exonuclease E415G mutation nor the copy number variation of the plasmepsin II gene (Pfpm2), associated with piperaquine resistance in Cambodia, was detected in Senegalese parasites.

Monitoring the Efficacy and Safety of Artemisinin-Based Combination Therapies: A Review and Network Meta-analysis of Antimalarial Therapeutic Efficacy Trials in Cameroon

Introduction

Artemisinin-based combination therapies (ACTs) are the first-line antimalarial drugs used to treat uncomplicated Plasmodium falciparum alaria in many endemic countries worldwide. The present work reviewed the therapeutic efficacy of ACT in Cameroon more than 10 years after the initial change in national drug policy in 2004.

Methods

A PubMed literature search was performed to analyse clinical trials conducted in Cameroon from 2001 to May 2017. Clinical studies that evaluated ACT for the treatment of uncomplicated falciparum malaria in children or adults, and reported efficacy and/or safety, were included. In addition, a small network meta-analysis (NMA) with a frequentist approach was performed.

Results

Six papers were selected from 48 articles screened and were full-text reviewed. The efficacy of both artemether-lumefantrine (AL) and artesunate-amodiaquine (ASAQ) ranged from moderate to high, with polymerase chain reaction-corrected cure rates ranging from 96.7 to 100% and 88.2 to 100%, respectively, in per-protocol analysis, and 86.2 to 96.7% and 74.0 to 90.6%, respectively, in intention-to-treat analysis. The malaria evidence network suggested that AL and ASAQ efficacies were comparable. The highest day 3 parasite positivity rate was 8.2% for ASAQ and 4% for AL. A novel ACT, artesunate-atovaquoneproguanil (ASATPG) was tested once and showed a cure rate of 100%. Based on an ITT approach, the NMA revealed that AL was more efficacious than ASAQ, but the difference was not statistical significant (706 participants, three randomised clinical trials (RCT); OR 1.25, 95%CI 0.78–2.00). Adverse events ranged from mild to moderate severity but were not directly attributed to drug intake.

Conclusion

ACTs are still effective and safe in Cameroon; however, there are insufficient data on their efficacy, safety and tolerability, therefore more RCTs should be conducted, including novel ACTs.

Electronic supplementary material

The online version of this article (10.1007/s40268-018-0259-3) contains supplementary material, which is available to authorized users.

Choreoathetosis - an unusual adverse effect of dihydroartemisinin-piperaquine: a case report

Background

Dihydroartemisinin-piperaquine is a combination of dihydroartemisinin and piperaquine which is highly effective in the treatment of uncomplicated falciparum malaria. Its adverse effects are generally tolerable and temporary. Choreoathetosis, an involuntary movement disorder characterized by continuous irregular twisting of the body, is not a documented adverse effect of this medication.

Case presentation

A 41-year-old Cameroonian man of black African ethnicity was brought to our primary care hospital because over the previous 6 hours he had been experiencing involuntary twisting movements of his body and he no longer had control of his limbs. Earlier that day, he had been prescribed an appropriate dose of dihydroartemisinin-piperaquine in our hospital. The abnormal movements started approximately 3 hours after ingesting the first dose of the drug. The review of systems and his past history were unremarkable. On clinical examination, he was conscious and oriented but was unsteady and displayed continuous generalized irregular twisting movements combined with abrupt low amplitude flinging of his limbs. Dihydroartemisinin-piperaquine-induced generalized choreoathetosis was diagnosed. He was sedated with diazepam and dihydroartemisinin-piperaquine was discontinued. The antimalarial drug was substituted with artemether-lumefantrine combination. The clinical progress was good and he was discharged home after 72 hours. No further abnormalities were noted during 7 months of follow-up.

Conclusion

Although dihydroartemisinin-piperaquine is increasingly popular as a well-tolerated/efficacious antimalarial drug, clinicians must note the rare possibility of choreoathetosis as an adverse effect of this medication and educate patients accordingly.

Comparison of anti-malarial drugs efficacy in the treatment of uncomplicated malaria in African children and adults using network meta-analysis

Background

Artemisinin-based combination therapy (ACT) and novel drug combinations are available and used in African countries to treat uncomplicated malaria. Network meta-analysis methods are rarely and poorly applied for the comparison of their efficacies. This method was applied on a set of randomized controlled trials to illustrate its usefulness.

Methods

A literature review available in Pubmed was conducted in July 2016. Eligible studies, conducted in sub-Saharan Africa, published between 2002 and 2016, focused on randomized controlled trials of at least two artemisinin-based combinations to treat uncomplicated malaria in children and adults. Agglomerate data were: the number of PCR-corrected adequate clinical and parasitological response (ACPR) on day 28, used as the primary endpoint in all interventions, the number of participants and the list of treatments. A Bayesian random effect meta-analysis using a binary outcome was the method to compare the efficacy. Ranking measure was used to obtain a hierarchy of the competing interventions.

Results

In total, 76 articles were included; 13 treatment regimens were involved and tested in 36,001 patients. Using artemether–lumefantrine (AL) as the common comparator for the entire network, 12 relative treatment effects were estimated and indirect comparisons were obtained. Dihydroartemisinin–piperaquine (DHAP) was shown to be more effective than AL (odds ratio [OR] = 1.92; 95% CI 1.30–2.82; 19,163 patients), ASAQ (OR = 1.70; 95% CI 1.10–2.64; 14,433 patients), and amodiaquine–sulfadoxine–pyrimethamine (AQSP): OR = 2.20; 95% CI 1.21–3.96; 8863 patients. Artesunate–amodiaquine (ASAQ) was comparable to AL (OR = 1.11; 95% CI 0.84–1.45; 21,235 patients). No significant difference was found between artesunate and mefloquine (ASMQ) and AL (OR = 1.20; 95% CI = 0.52-2.8; 13,824 participants). According to treatment ranking, among the WHO-recommended ACT medicines, DHAP was shown to be the most efficacious.

Conclusions

Based on the available evidence, this study demonstrated the superiority of DHAP among currently recommended artemisinin-based combinations. The application of the methods described here may be helpful to gain better understanding of treatment efficacy and improve future decisions. However, more data are needed to allow robust conclusions about the results in comparison with novel drugs. Further surveillance of the efficacy of anti-malarial drugs and clinical trials are needed to closely follow the evolution of the epidemiology of drug-resistant malaria in Africa.

Electronic supplementary material

The online version of this article (doi:10.1186/s12936-017-1963-0) contains supplementary material, which is available to authorized users.

Efficacy and Safety of Artesunate-Amodiaquine versus Artemether-Lumefantrine in the Treatment of Uncomplicated Plasmodium falciparum Malaria in Sentinel Sites across Côte d'Ivoire

Two years after the introduction of free Artesunate-Amodiaquine (ASAQ) and Artemether-Lumefantrine (AL) for the treatment of uncomplicated malaria in public health facilities in Côte d'Ivoire, we carried out this study to compare their efficacy and tolerability in three surveillance sites. It was a multicentre open randomised clinical trial of 3-day ASAQ treatment against AL for the treatment of 2 parallel groups of patients aged 2 years and above. The endpoints were (1) Adequate Clinical and Parasitological Response (ACPR) at day 28 and (2) the clinical and biological tolerability. Of the 300 patients who were enrolled 289, with 143 (49.5%) and 146 (50.5%) in the ASAQ and AL groups, respectively, correctly followed the WHO 2003 protocol we used. The PCR-corrected ACPR was 99.3% for each group. More than 94% of patients no longer showed signs of fever, 48 hours after treatment. Approximately 78% of the people in the ASAQ group had a parasite clearance time of 48 hours or less compared to 81% in the AL group (p = 0.496). Both drugs were found to be well tolerated by the patients. This study demonstrates the effectiveness and tolerability of ASAQ and AL supporting their continuous use for the treatment of uncomplicated P. falciparum malaria infection in Côte d'Ivoire.

The emerging threat of artemisinin resistance in malaria: focus on artemether-lumefantrine

The development of artemisinin resistance in the Greater Mekong Subregion poses a significant threat to malaria elimination. Artemisinin-based combination therapies including artemether-lumefantrine (AL) are recommended by WHO as first-line treatment for uncomplicated Plasmodium falciparum malaria. This article provides a comprehensive review of the existing and latest data as a basis for interpretation of observed variability in parasite sensitivity to AL over the last 5 years. Clinical efficacy and preclinical data from a range of endemic countries are summarized, including potential molecular markers of resistance. Overall, AL remains effective in the treatment of uncomplicated P. falciparum malaria in most regions. Establishing validated molecular markers for resistance and strict efficacy monitoring will reinforce timely updates of treatment policies.

Plasmodium falciparum susceptibility to standard and potential anti-malarial drugs in Dakar, Senegal, during the 2013-2014 malaria season

Background

In 2006, the Senegalese National Malaria Control Programme recommended artemisinin-based combination therapy (ACT) as the first-line treatment for uncomplicated malaria. Since the introduction of ACT, there have been very few reports on the level of Plasmodium falciparum resistance to anti-malarial drugs. An ex vivo susceptibility study was conducted on local isolates obtained from the Hôpital Principal de Dakar (Dakar, Senegal) from November 2013 to January 2014.

Methods

Eighteen P. falciparum isolates were sussessfully assessed for ex vivo susceptibility to chloroquine (CQ), quinine (QN), monodesethylamodiaquine (MDAQ), the active metabolite of amodiaquine, mefloquine (MQ), lumefantrine (LMF), artesunate (AS), dihydroartemisinin (DHA), the active metabolite of artemisinin derivatives, pyronaridine (PND), piperaquine (PPQ), and, Proveblue (PVB), a methylene blue preparation, using the HRP2-based ELISA test.

Results

The prevalence of isolates with reduced susceptibility was 55.6% for MQ, 50% for CQ, 5.6% for QN and MDAQ, and 0% for DHA, AS and LMF. The mean IC₅₀ for PND, PPQ and PVB were 5.8 nM, 32.2 nM and 5.3 nM, respectively.

Conclusions

The prevalence of isolates with a reduced susceptibility to MQ remains high and stable in Dakar. Since 2004, the prevalence of CQ resistance decreased, but rebounded in 2013 in Dakar. PND, PPQ and PVB showed high in vitro activity in P. falciparum parasites from Dakar.

Multinormal in vitro distribution of Plasmodium falciparum susceptibility to piperaquine and pyronaridine

Background

In 2002, the World Health Organization recommended that artemisinin-based combination therapy (ACT) be used to treat uncomplicated malaria. Dihydroartemisinin-piperaquine and artesunate-pyronaridine are two of these new combinations. The aim of the present work was to assess the distribution of the in vitro values of pyronaridine (PND) and piperaquine (PPQ) and to define a cut-off for reduced susceptibility for the two anti-malarial drugs.

Methods

The distribution and range of the 50% inhibitory concentration values (IC₅₀) of PND and PPQ were determined for 313 isolates obtained between 2008 and 2012 from patients hospitalized in France for imported malaria. The statistical Bayesian analysis was designed to answer the specific question of whether Plasmodium falciparum has different phenotypes of susceptibility to PND and PPQ.

Results

The PND IC₅₀ values ranged from 0.6 to 84.6 nM, with a geometric mean of 21.1 ± 16.0 nM (standard deviation). These values were classified into three components. The PPQ IC₅₀ values ranged from 9.8 to 217.3 nM, and the geometric mean was 58.0 ± 34.5 nM. All 313 PPQ values were classified into four components. Isolates with IC₅₀ values greater than 60 nM or four-fold greater than 3D7 IC₅₀ are considered isolates that have reduced susceptibility to PND and those with IC₅₀ values greater than 135 nM or 2.3-fold greater than 3D7 IC₅₀ are considered isolates that have reduced susceptibility to PPQ.

Conclusion

The existence of at least three phenotypes for PND and four phenotypes for PPQ was demonstrated. Based on the cut-off values, 18 isolates (5.8%) and 13 isolates (4.2%) demonstrated reduced susceptibility to PND and PPQ, respectively.

Antimalarial chemotherapy: orally curative artemisinin-derived trioxane dimer esters

Eight new artemisinin-derived trioxane dimer esters 5 have been prepared and tested for antimalarial efficacy in malaria-infected mice. At a single oral dose of only 6mg/kg combined with 18mg/kg of mefloquine, each of the dimer esters 5 outperformed the antimalarial drug artemether (2). The most efficacious dimer, dichlorobenzoate ester 5h, prolonged mouse survival past day 30 of infection with three of the four mice in this group having no detectable parasitemia and appearing and acting healthy on day 30.

Performance and clinical usefulness of the Optimal-IT® test in the treatment of confirmed malaria cases in rural areas in Côte d'Ivoire

Background

In Africa, malaria care is mostly based on clinical presumption and the general application of antimalarial treatment to all febrile episodes over several years. Treatment limited to confirmed cases might curb the practice of equating fever with malaria, antimalarial drug abuse and the extension of Plasmodium resistance, provided that powerful and reliable rapid diagnostic tests are used. This study aimed at determining the performances of the Optimal-IT® test in the strategy for the exclusive treatment of uncomplicated malaria in rural areas.

Materials and Methods

A prospective study conducted in the forest region of San Pedro, Côte d'Ivoire, included patients exhibiting clinical signs of uncomplicated malaria who gave their consent and benefited from thick blood film (TBF), blood smear (BS) and Optimal-IT® (pLDH-based) test. Rapid diagnostic test (RDT) results were taken into consideration to decide on malaria treatment and then compared with TBF/BS results (reference) to assess the performances and clinical usefulness of the RDT.

Results

The mean age of the 384 patients included (209 men, 175 women) was 28 years and the mean temperature was 38.1°C. TBF/BS and Optimal-IT® were concordant in 92% of patients but discordant in 10 false negative (3%) and 19 false-positive patients (5%). The average parasite density of P. falciparum was 25,600 trophozoites/μl. The performances calculated were: sensitivity=95%, specificity=91%, positive predictive value=90%, negative predictive value=95%, positive likelihood ratio=10, negative likelihood ratio=0.06 and diagnostic odds ratio=166, indicating that Optimal-IT® is a powerful and credible diagnostic tool. The 193 RDT-positive patients treated were healed, despite three recurrence cases at day (D) D17, D25 and D27, respectively. RDT-negative patients received various treatments (antibiotics, paracetamol), but two patients among them presented with a bout of malaria on D7. None of the previously untreated patients returned with severe malaria.

Conclusions

The Optimal-IT® test, which is already used in the field, showed good performances to effectively detect patients with and without malaria. It is therefore adapted to the malaria treatment strategy limited to confirmed cases.

Surveillance of artemether-lumefantrine associated Plasmodium falciparum multidrug resistance protein-1 gene polymorphisms in Tanzania

BACKGROUND

Resistance to anti-malarials is a major public health problem worldwide. After deployment of artemisinin-based combination therapy (ACT) there have been reports of reduced sensitivity to ACT by malaria parasites in South-East Asia. In Tanzania, artemether-lumefantrine (ALu) is the recommended first-line drug in treatment of uncomplicated malaria. This study surveyed the distribution of the Plasmodium falciparum multidrug resistance protein-1 single nucleotide polymorphisms (SNPs) associated with increased parasite tolerance to ALu, in Tanzania.

METHODS

A total of 687 Plasmodium falciparum positive dried blood spots on filter paper and rapid diagnostic test strips collected by finger pricks from patients attending health facilities in six regions of Tanzania mainland between June 2010 and August 2011 were used. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique was used to detect Pfmdr1 SNPs N86Y, Y184F and D1246Y.

RESULTS

There were variations in the distribution of Pfmdr1 polymorphisms among regions. Tanga region had exceptionally high prevalence of mutant alleles, while Mbeya had the highest prevalence of wild type alleles. The haplotype YFY was exclusively most prevalent in Tanga (29.6%) whereas the NYD haplotype was the most prevalent in all other regions. Excluding Tanga and Mbeya, four, most common Pfmdr1 haplotypes did not vary between the remaining four regions (χ² = 2.3, p = 0.512). The NFD haplotype was the second most prevalent haplotype in all regions, ranging from 17% - 26%.

CONCLUSION

This is the first country-wide survey on Pfmdr1 mutations associated with ACT resistance. Distribution of individual Pfmdr1 mutations at codons 86, 184 and 1246 varies throughout Tanzanian regions. There is a general homogeneity in distribution of common Pfmdr1 haplotypes reflecting strict implementation of ALu policy in Tanzania with overall prevalence of NFD haplotype ranging from 17 to 26% among other haplotypes. With continuation of ALu as first-line drug this haplotype is expected to keep rising, thus there is need for continued pharmacovigilance studies to monitor any delayed parasite clearance by the drug.

Does the Use of Dihydroartemisinin-Piperaquine in Treating Patients with Uncomplicated falciparum Malaria Reduce the Risk for Recurrent New falciparum Infection More Than Artemether-Lumefantrine?

Malaria contributes significantly to the global disease burden. The World Health Organization recommended the use of artemisinin-based combination therapies (ACTs) for treatment of uncomplicated falciparum malaria a decade ago in response to problems of drug resistance. This review compared two of the ACTs-Dihydroartemisinin-Piperaquine (DP) and Artemether-Lumefantrine (AL) to provide evidence which one has the ability to offer superior posttreatment prophylaxis at 28 and 42 days posttreatment. Four databases (MEDLINE, EMBASE, Cochrane Database and Global Health) were searched on June 2, 2013 and a total of seven randomized controlled trials conducted in sub-Sahara Africa were included. Results involving 2, 340 participants indicates that reduction in risk for recurrent new falciparum infections (RNIs) was 79% at day 28 in favour of DP [RR, 0.21; 95% CI: 0.14 to 0.32, P < 0.001], and at day 42 was 44% favouring DP [RR, 0.56; 95% CI: 0.34 to 0.90; P = 0.02]. No significant difference was seen in treatment failure rates between the two drugs at days 28 and 42. It is concluded that use of DP offers superior posttreatment prophylaxis compared to AL in the study areas. Hence DP can help reduce malaria cases in such areas more than AL.

Artemisinin-based combination therapies are efficacious and safe for treatment of uncomplicated malaria in HIV-infected Ugandan children

BACKGROUND

Artemisinin-based combination therapies (ACTs) are highly efficacious and safe, but data from human immunodeficiency virus (HIV)-infected children concurrently receiving antiretroviral therapy (ART) and ACTs are limited.

METHODS

We evaluated 28-day outcomes following malaria treatment with artemether-lumefantrine (AL) or dihydroartemisinin-piperaquine (DP) in 2 cohorts of HIV-infected Ugandan children taking various ART regimens. In one cohort, children <6 years of age were randomized to lopinavir/ritonavir (LPV/r) or nonnucleoside reverse transcriptase inhibitor-based ART and treated with AL for uncomplicated malaria. In another cohort, children <12 months of age were started on nevirapine-based ART if they were eligible, and randomized to AL or DP for the treatment of their first and all subsequent uncomplicated malaria episodes.

RESULTS

There were 773 and 165 treatments for malaria with AL and DP, respectively. Initial response to therapy was excellent, with 99% clearance of parasites and <1% risk of repeat therapy within 3 days. Recurrent parasitemia within 28 days was common following AL treatment. The risk of recurrent parasitemia was significantly lower among children taking LPV/r-based ART compared with children taking nevirapine-based ART following AL treatment (15.3% vs 35.5%, P = .009), and those treated with DP compared with AL (8.6% vs 36.2%, P < .001). Both ACT regimens were safe and well tolerated.

CONCLUSIONS

Treatment of uncomplicated malaria with AL or DP was efficacious and safe in HIV-infected children taking ART. However, there was a high risk of recurrent parasitemia following AL treatment, which was significantly lower in children taking LPV/r-based ART compared with nevirapine-based ART.

Comparative impacts over 5 years of artemisinin-based combination therapies on Plasmodium falciparum polymorphisms that modulate drug sensitivity in Ugandan children

BACKGROUND

Artemisinin-based combination therapies, including artemether-lumefantrine (AL) and dihydroartemisinin-piperaquine (DP), are recommended to treat uncomplicated falciparum malaria. Sensitivities to components of AL and DP are impacted by polymorphisms in pfmdr1 and pfcrt. We monitored changes in prevalences of polymorphisms in Tororo, Uganda, from 2008 to 2012.

METHODS

Polymorphic loci in pfmdr1 and pfcrt were characterized in samples from 312 children randomized to AL or DP for each episode of uncomplicated malaria (50 samples per arm for each 3-month interval) utilizing a fluorescent microsphere assay. Treatment outcomes and impacts of prior therapies were also characterized.

RESULTS

Prevalence increased significantly over time for pfmdr1 N86 (AL: odds ratio [OR], 2.08 [95% confidence interval {CI}, 1.83-2.38]; DP: 1.41 [95% CI, 1.25-1.57]), pfmdr1 D1246 (AL: 1.46 [95% CI, 1.29-1.64]; DP: 1.36 [95% CI, 1.23-1.50]), and pfcrt K76 (AL: 3.37 [95% CI, 1.85-6.16]; DP: 5.84 [95% CI, 1.94-17.53], and decreased for pfmdr1 Y184 (AL: 0.78 [95% CI, .70-.86]; DP: 0.84 [95% CI, .76-1.50]); changes were consistently greater in the AL arm. Recent AL treatment selected for pfmdr1 N86, D1246, and 184F in subsequent episodes; DP selected for the opposite alleles.

CONCLUSIONS

Genotypes with decreased sensitivity to AL components increased over time. This increase was greater in children receiving AL, suggesting that the choice of treatment regimen can profoundly influence parasite genetics and drug sensitivity.

CLINICAL TRIALS REGISTRATION

NCT00527800.

The survival times of malaria-infected mice are prolonged more by several new two-carbon-linked artemisinin-derived dimer carbamates than by the trioxane antimalarial drug artemether

Sixteen new artemisinin-derived 2-carbon-linked trioxane dimers were prepared to study chemical structure/antimalarial activity relationships (SAR). Administering a very low single oral dose of only 5mg/kg of dimer secondary alcohol 6a or 6b plus 15 mg/kg of mefloquine hydrochloride prolonged the lives of Plasmodium berghei-infected mice to an average of 25 days after infection. This ACT chemotherapy result is of high medicinal significance because the antimalarial efficacy of the popular trioxane drug artemether (2) plus mefloquine under the same conditions was significantly lower (only 20 day average survival). NH-aryl carbamate derivatives 7e, 7i, and 7j of 2-carbon-linked dimer alcohol 6b also significantly outperformed artemether (2) in prolonging the survival times (25-27 days) of malaria-infected mice.

Dihydroartemisinin-piperaquine for treating uncomplicated Plasmodium falciparum malaria

BACKGROUND

The World Health Organization (WHO) recommends Artemisinin-based Combination Therapy (ACT) for treating uncomplicated Plasmodium falciparum malaria. This review aims to assist the decision-making of malaria control programmes by providing an overview of the relative effects of dihydroartemisinin-piperaquine (DHA-P) versus other recommended ACTs.

OBJECTIVES

To evaluate the effectiveness and safety of DHA-P compared to other ACTs for treating uncomplicated P. falciparum malaria in adults and children.

SEARCH METHODS

We searched the Cochrane Infectious Diseases Group Specialized Register; the Cochrane Central Register of Controlled Trials (CENTRAL) published in The Cochrane Library; MEDLINE; EMBASE; LILACS, and the metaRegister of Controlled Trials (mRCT) up to July 2013.

SELECTION CRITERIA

Randomized controlled trials comparing a three-day course of DHA-P to a three-day course of an alternative WHO recommended ACT in uncomplicated P. falciparum malaria.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed trials for eligibility and risk of bias, and extracted data. We analysed primary outcomes in line with the WHO 'Protocol for assessing and monitoring antimalarial drug efficacy' and compared drugs using risk ratios (RR) and 95% confidence intervals (CI). Secondary outcomes were effects on gametocytes, haemoglobin, and adverse events. We assessed the quality of evidence using the GRADE approach.

MAIN RESULTS

We included 27 trials, enrolling 16,382 adults and children, and conducted between 2002 and 2010. Most trials excluded infants aged less than six months and pregnant women. DHA-P versus artemether-lumefantrineIn Africa, over 28 days follow-up, DHA-P is superior to artemether-lumefantrine at preventing further parasitaemia (PCR-unadjusted treatment failure: RR 0.34, 95% CI 0.30 to 0.39, nine trials, 6200 participants, high quality evidence), and although PCR-adjusted treatment failure was below 5% for both ACTs, it was consistently lower with DHA-P (PCR-adjusted treatment failure: RR 0.42, 95% CI 0.29 to 0.62, nine trials, 5417 participants, high quality evidence). DHA-P has a longer prophylactic effect on new infections which may last for up to 63 days (PCR-unadjusted treatment failure: RR 0.71, 95% CI 0.65 to 0.78, two trials, 3200 participants, high quality evidence).In Asia and Oceania, no differences have been shown at day 28 (four trials, 1143 participants, moderate quality evidence), or day 63 (one trial, 323 participants, low quality evidence).Compared to artemether-lumefantrine, no difference was seen in prolonged QTc (low quality evidence), and no cardiac arrhythmias were reported. The frequency of other adverse events is probably similar with both combinations (moderate quality evidence). DHA-P versus artesunate plus mefloquineIn Asia, over 28 days follow-up, DHA-P is as effective as artesunate plus mefloquine at preventing further parasitaemia (PCR-unadjusted treatment failure: eight trials, 3487 participants, high quality evidence). Once adjusted by PCR to exclude new infections, treatment failure at day 28 was below 5% for both ACTs in all eight trials, but lower with DHA-P in two trials (PCR-adjusted treatment failure: RR 0.41 95% CI 0.21 to 0.80, eight trials, 3482 participants, high quality evidence). Both combinations contain partner drugs with very long half-lives and no consistent benefit in preventing new infections has been seen over 63 days follow-up (PCR-unadjusted treatment failure: five trials, 2715 participants, moderate quality evidence).In the only trial from South America, there were fewer recurrent parastaemias over 63 days with artesunate plus mefloquine (PCR-unadjusted treatment failure: RR 6.19, 95% CI 1.40 to 27.35, one trial, 445 participants, low quality evidence), but no differences were seen once adjusted for new infections (PCR-adjusted treatment failure: one trial, 435 participants, low quality evidence).DHA-P is associated with less nausea, vomiting, dizziness, sleeplessness, and palpitations compared to artesunate plus mefloquine (moderate quality evidence). DHA-P was associated with more frequent prolongation of the QTc interval (low quality evidence), but no cardiac arrhythmias were reported.

AUTHORS' CONCLUSIONS

In Africa, dihydroartemisinin-piperaquine reduces overall treatment failure compared to artemether-lumefantrine, although both drugs have PCR-adjusted failure rates of less than 5%. In Asia, dihydroartemisinin-piperaquine is as effective as artesunate plus mefloquine, and is better tolerated.

Monitoring the efficacy and safety of three artemisinin based-combinations therapies in Senegal: results from two years surveillance

Background

Malaria remains a major public health problem in developing countries. Then in these countries prompt access to effective antimalarial treatment such as Artemisinin based-Combination Therapies (ACT) proves to be an essential tool for controlling the disease. In Senegal, since 2006 a nationwide scaling up program of ACT is being implemented. In this context it has become relevant to monitor ACT efficacy and provide recommendations for the Senegalese national malaria control program.

Methods

An open randomized trial was conducted during two malaria transmission seasons (2011 and 2012) to assess the efficacy and safety of three combinations: dihydro-artemisinin-piperaquine (DHAPQ), artemether-lumefantrine (AL) and artesunate-amodiaquine (ASAQ). The primary end point of the study was represented by a PCR adjusted adequate clinical and parasitological response (ACPR) at day 28. Secondary end points included: (i) a ACPR at days 35 and 42, (ii) a parasite and fever clearance time, (iii) ACTs safety and tolerability. The 2003 WHO’s protocol for antimalarial drug evaluation was used to assess each outcome.

Results

Overall, 534 patients were randomized selected to receive, either ASAQ (n = 180), AL (n = 178) or DHAPQ (n = 176). The PCR adjusted ACPR at day 28 was 99.41% for the group ASAQ, while that was 100% in the AL and DHAPQ groups (p = 0.37). The therapeutic efficacy was evaluated at 99.37% in the ASAQ arm versus 100% in AL and DHAPQ arm at day 35 (p = 0.37). At day 42, the ACPR was 99.27% in the ASAQ group versus 100% for both AL and DHAPQ groups, (p = 0.36). No serious adverse event was noted during the study period. Also a similar safety profile was noted in the 3 study groups.

Conclusion

In the context of scaling up of ACTs in Senegal, ASAQ, AL and DHAPQ are highly effective and safe antimalarial drugs. However, it’s remains important to continue to monitor their efficacy.

Trial registration

PACTR 201305000552290.

The effect of dosing regimens on the antimalarial efficacy of dihydroartemisinin-piperaquine: a pooled analysis of individual patient data

BACKGROUND

Dihydroartemisinin-piperaquine (DP) is increasingly recommended for antimalarial treatment in many endemic countries; however, concerns have been raised over its potential under dosing in young children. We investigated the influence of different dosing schedules on DP's clinical efficacy.

METHODS AND FINDINGS

A systematic search of the literature was conducted to identify all studies published between 1960 and February 2013, in which patients were enrolled and treated with DP. Principal investigators were approached and invited to share individual patient data with the WorldWide Antimalarial Resistance Network (WWARN). Data were pooled using a standardised methodology. Univariable and multivariable risk factors for parasite recrudescence were identified using a Cox's regression model with shared frailty across the study sites. Twenty-four published and two unpublished studies (n = 7,072 patients) were included in the analysis. After correcting for reinfection by parasite genotyping, Kaplan-Meier survival estimates were 97.7% (95% CI 97.3%-98.1%) at day 42 and 97.2% (95% CI 96.7%-97.7%) at day 63. Overall 28.6% (979/3,429) of children aged 1 to 5 years received a total dose of piperaquine below 48 mg/kg (the lower limit recommended by WHO); this risk was 2.3-2.9-fold greater compared to that in the other age groups and was associated with reduced efficacy at day 63 (94.4% [95% CI 92.6%-96.2%], p<0.001). After adjusting for confounding factors, the mg/kg dose of piperaquine was found to be a significant predictor for recrudescence, the risk increasing by 13% (95% CI 5.0%-21%) for every 5 mg/kg decrease in dose; p = 0.002. In a multivariable model increasing the target minimum total dose of piperaquine in children aged 1 to 5 years old from 48 mg/kg to 59 mg/kg would halve the risk of treatment failure and cure at least 95% of patients; such an increment was not associated with gastrointestinal toxicity in the ten studies in which this could be assessed.

CONCLUSIONS

DP demonstrates excellent efficacy in a wide range of transmission settings; however, treatment failure is associated with a lower dose of piperaquine, particularly in young children, suggesting potential for further dose optimisation.

In vitro piperaquine susceptibility is not associated with the Plasmodium falciparum chloroquine resistance transporter gene

Background

Dihydroartemisinin-piperaquine is a new ACT that is administered as single daily dose for three days and has been demonstrated to be tolerated and highly effective for the treatment of uncomplicated Plasmodium falciparum malaria. Piperaquine was used alone to replace chloroquine as the first-line treatment for uncomplicated malaria in China in response to increasing chloroquine resistance in the 1970s. However, the rapid emergence of piperaquine-resistant strains that resulted in the cessation of its use in China in the 1980s, suggests that there is cross-resistance between piperaquine and chloroquine. Very few data are available on cross-resistance between piperaquine and chloroquine, and the data that do exist are often contradictory.

Methods

In total, 280 P. falciparum isolates, collected between April 2008 and June 2012 from patients hospitalized in France with imported malaria from a malaria-endemic country, were assessed ex vivo for piperaquine and chloroquine susceptibilities by using the standard 42-hour 3H-hypoxanthine uptake inhibition method. The chloroquine resistance-associated mutation K76T in pfcrt was also investigated for the 280 isolates.

Results

The IC₅₀ for piperaquine ranged from 9.8 nM to 217.3 nM (mean = 81.3 nM. The IC₅₀ for chloroquine ranged from 5.0 nM to 1,918 nM (mean = 83.6 nM. A significant but low correlation was observed between the Log IC₅₀ values for piperaquine and chloroquine (r = 0.145, p < 0.001). However, the coefficient of determination of 0.021 indicates that only 2.1% of the variation in the response to piperaquine is explained by the variation in the response to chloroquine. The mean value for piperaquine was 74.0 nM in the Pfcrt K76 wild-type group (no = 125) and 87.7 nM in the 76 T mutant group (no = 155). This difference was not significant (p = 0.875, Mann Whitney U test).

Conclusions

The present work demonstrates that there was no cross-resistance between piperaquine and chloroquine among 280 P. falciparum isolates and that piperaquine susceptibility is not associated with pfcrt, the gene involved in chloroquine resistance. These results confirm the efficacy of piperaquine in association with dihydroartemisinin and support its use in areas in which parasites are resistant to chloroquine.

Use of artemether-lumefantrine to treat malaria during pregnancy: what do we know and need to know?

Artemether-lumefantrine is a fixed-dose combination containing 20 mg artemether/120 mg lumefantrine per tablet, used for treating uncomplicated malaria in patients weighing ≥5 kg. It is the first artemisinin-based combination registered in some European countries and in the USA. It is marketed in Europe as Riamet(®) (Novartis, Basel, Switzerland) and in malaria-endemic countries as Coartem(®) (Novartis). Safety concerns prevent early pregnancy usage, while limited postmarketing surveillance has delayed safety assessment and policy development. Large clinical studies, postmarketing surveillance and pharmacovigillance ongoing in some countries may soon bridge safety issues. Fatty diet requirements for optimal absorption, pregnancy-induced changes in pharmacokinetics, pregnancy-related anorexia and food taboos, and emerging reduced parasite sensitivity to artemisinin, challenges optimal artemether-lumefantrine dosing and efficacy during pregnancy. This evaluation addresses drug usage, safety concerns following early exposure, implications for changed pharmacokinetics and reduced parasite susceptibility. Clinical-use updates and strategies to address some knowledge gaps including key operational research are discussed.

A randomized trial of artemether-lumefantrine and dihydroartemisinin-piperaquine in the treatment of uncomplicated malaria among children in western Kenya

Background

Artemether-lumefantrine (AL) was adopted as first-line treatment for uncomplicated malaria in Kenya in 2006. Monitoring drug efficacy at regular intervals is essential to prevent unnecessary morbidity and mortality. The efficacy of AL and dihydroartemisinin-piperaquine (DP) were evaluated for the treatment of uncomplicated malaria in children aged six to 59 months in western Kenya.

Methods

From October 2010 to August 2011, children with fever or history of fever with uncomplicated Plasmodium falciparum mono-infection were enrolled in an in vivo efficacy trial in accordance with World Health Organization (WHO) guidelines. The children were randomized to treatment with a three-day course of AL or DP and efficacy outcomes were measured at 28 and 42 days after treatment initiation.

Results

A total of 137 children were enrolled in each treatment arm. There were no early treatment failures and all children except one had cleared parasites by day 3. Polymerase chain reaction (PCR)-uncorrected adequate clinical and parasitological response rate (ACPR) was 61% in the AL arm and 83% in the DP arm at day 28 (p = 0.001). PCR-corrected ACPR at day 28 was 97% in the AL group and 99% in the DP group, and it was 96% in both arms at day 42.

Conclusions

AL and DP remain efficacious for the treatment of uncomplicated malaria among children in western Kenya. The longer half-life of piperaquine relative to lumefantrine may provide a prophylactic effect, accounting for the lower rate of re-infection in the first 28 days after treatment in the DP arm.

In vitro sensitivities of Plasmodium falciparum isolates from the China-Myanmar border to piperaquine and association with polymorphisms in candidate genes

The recent reports of resistance in Plasmodium falciparum to artemisinin derivatives and their partner drugs demand intensive studies toward understanding the molecular mechanisms of resistance. In this study, we examined the in vitro susceptibility of 63 P. falciparum field isolates collected from the China-Myanmar border area to chloroquine (CQ) and piperaquine (PPQ). Parasite isolates remained highly resistant to CQ, with the geometric mean 50% inhibitory concentration (IC50) of 252.7 nM and a range of 51.9 to 1,052.0 nM. In comparison, these parasites had a geometric mean IC50 of 28.4 nM for PPQ, with a fairly wide range of 5.3 to 132.0 nM, suggesting that certain parasite isolates displayed relatively high levels of resistance to PPQ. Interestingly, within the 4 years of study, the parasites exhibited a continuous decline in susceptibilities to both CQ and PPQ, and there was a significant correlation between responses to CQ and PPQ (Pearson correlation coefficient = 0.79, P < 0.0001). Consistent with the CQ-resistant phenotype, all parasites carried the pfcrt K76T mutation, and most parasites had the CVIET type that is prevalent in Southeast Asia. In contrast, pfmdr1 mutations were relatively rare, and no gene amplification was detected. Only the pfmdr1 N1042D mutation was associated with resistance to CQ. For the pfmrp1 gene, four substitutions reached relatively high prevalence of >22%, and the I876V mutation was associated with reduced sensitivity to CQ. However, we could not establish a link between PPQ responses and the polymorphisms in the three genes associated with quinoline drug resistance.

Sequential combined treatment with allopurinol and benznidazole in the chronic phase of Trypanosoma cruzi infection: a pilot study

OBJECTIVES

Even though the use of combined drugs has been proved to be effective in other chronic infections, assessment of combined treatment of antiparasitic drugs in human Chagas' disease has not been performed. Herein, a pilot study was conducted to evaluate the tolerance and side effects of a sequential combined treatment of two antiparasitic drugs, allopurinol and benznidazole, in the chronic phase of Trypanosoma cruzi infection.

PATIENTS AND METHODS

Changes in total and T. cruzi-specific T and B cells were monitored during a median follow-up of 36 months. Allopurinol was administered for 3 months (600 mg/day) followed by 30 days of benznidazole (5 mg/kg/day) in 11 T. cruzi-infected subjects.

RESULTS

The combined sequential treatment of allopurinol and benznidazole was well tolerated. The levels of T. cruzi-specific antibodies significantly decreased after sequential combined treatment, as determined by conventional serology and by a multiplex assay using recombinant proteins. The frequency of T. cruzi-specific interferon-γ-producing T cells significantly increased after allopurinol treatment and decreased to background levels following benznidazole administration in a substantial proportion of subjects evaluated. The levels of total naive (CD45RA + CCR7 + CD62L+) CD4 + and CD8 + T cells were restored after allopurinol administration and maintained after completion of the combined drug protocol, along with a decrease in T cell activation in total peripheral CD4 + and CD8 + T cells.

CONCLUSIONS

This pilot study shows that the combination of allopurinol and benznidazole induces significant modifications in T and B cell responses indicative of a reduction in parasite burden, and sustains the feasibility of administration of two antiparasitic drugs in the chronic phase of Chagas' disease.

Malaria-infected mice live until at least day 30 after a new artemisinin-derived thioacetal thiocarbonate combined with mefloquine are administered together in a single, low, oral dose

In only three steps and in 21-67% overall yields from the natural trioxane artemisinin, a series of 21 new trioxane C-10 thioacetals was prepared. Upon receiving a single oral dose of only 6 mg/kg of the monomeric trioxane 12c combined with 18 mg/kg of mefloquine hydrochloride, Plasmodium berghei-infected mice survived on average 29.8 days after infection. Two of the four mice in this group had no parasites detectable in their blood on day 30 after infection, and they behaved normally and appeared healthy. One of the mice had 11% blood parasitemia on day 30, and one mouse in this group died on day 29. Of high medicinal importance, the efficacy of this ACT chemotherapy is much better than (almost double) the efficacy under the same conditions using as a positive control the popular trioxane drug artemether plus mefloquine hydrochloride (average survival time of only 16.5 days).

Prevalence of molecular markers of Plasmodium falciparum drug resistance in Dakar, Senegal

Background

As a result of the widespread resistance to chloroquine and sulphadoxine-pyrimethamine, artemisinin-based combination therapy (ACT) (including artemether-lumefantrine and artesunate-amodiaquine) has been recommended as a first-line anti-malarial regimen in Senegal since 2006. Intermittent preventive treatments with anti-malarial drugs based on sulphadoxine-pyrimethamine are also given to children or pregnant women once per month during the transmission season. Since 2006, there have been very few reports on the susceptibility of Plasmodium falciparum to anti-malarial drugs. To estimate the prevalence of resistance to several anti-malarial drugs since the introduction of the widespread use of ACT, the presence of molecular markers associated with resistance to chloroquine and sulphadoxine-pyrimethamine was assessed in local isolates at the military hospital of Dakar.

Methods

The prevalence of genetic polymorphisms in genes associated with anti-malarial drug resistance, i.e., Pfcrt, Pfdhfr, Pfdhps and Pfmdr1, and the copy number of Pfmdr1 were evaluated for a panel of 174 isolates collected from patients recruited at the military hospital of Dakar from 14 October 2009 to 19 January 2010.

Results

The Pfcrt 76T mutation was identified in 37.2% of the samples. The Pfmdr1 86Y and 184F mutations were found in 16.6% and 67.6% of the tested samples, respectively. Twenty-eight of the 29 isolates with the 86Y mutation were also mutated at codon 184. Only one isolate (0.6%) had two copies of Pfmdr1. The Pfdhfr 108N/T, 51I and 59R mutations were identified in 82.4%, 83.5% and 74.1% of the samples, respectively. The double mutant (108N and 51I) was detected in 83.5% of the isolates, and the triple mutant (108N, 51I and 59R) was detected in 75.3%. The Pfdhps 437G, 436F/A and 613S mutations were found in 40.2%, 35.1% and 1.8% of the samples, respectively. There was no double mutant (437G and 540E) or no quintuple mutant (Pfdhfr 108N, 51I and 59R and Pfdhps 437G and 540E). The prevalence of the quadruple mutant (Pfdhfr 108N, 51I and 59R and Pfdhps 437G) was 36.5%.

Conclusions

Since 2004, the prevalence of chloroquine resistance had decreased. The prevalence of isolates with high-level pyrimethamine resistance is 83.5%. The prevalence of isolates resistant to sulphadoxine is 40.2%. However, no quintuple mutant (Pfdhfr 108N, 51I and 59R and Pfdhps 437G and 540E), which is associated with a high level of sulphadoxine-pyrimethamine resistance, has been identified to date. The resistance to amodiaquine remains moderate.

Possible clinical failure of artemether-lumefantrine in an italian traveler with uncomplicated falciparum malaria

Artemisinin-combination therapies (ACTs) are recommended for the treatment of uncomplicated malaria in endemic areas with multidrug resistant Plasmodium falciparum. We report a case of possible artemether-lumefantrine clinical failure in an Italian traveler with uncomplicated P. falciparum malaria imported from Democratic Republic of Congo.