Efficacy of artemisinin-based combination treatments of uncomplicated falciparum malaria in under-five-year-old Nigerian children

Malaria Parasitemia and Severe Health Complications in Children Under Five Years of Age in Nigeria: A Study Using the Demographic and Health Survey (DHS) Malaria Indicator Survey (MIS) 2021

BACKGROUND

In Nigeria, 97% of the population is at risk of contracting malaria. It is transmitted by female Anopheles mosquitoes carrying the Plasmodium parasite and can be lethal. An estimated 55 million illnesses and 80,000 deaths per year result from it. Children under five are more likely to contract malaria. Efforts to control malaria in Nigeria include indoor residual spraying, insecticide-treated bed nets, and quick detection and treatment of confirmed cases with effective antimalarial medications. These attempts have been impeded by limited healthcare access, poor financing, and drug-resistant parasites. Thus, the study of the relationship between malaria complications and housing for children under five is essential.

METHODS

The Demographic and Health Survey (DHS) Malaria Indicator Survey (MIS) 2021, a nationally representative data set from developing countries on population and health, was used for this study. A sample size of 13,727 was employed (n=13,727). Logistic regression analyses were conducted to test the association between the type of place of residence and malaria complications (outcome).

RESULTS

Overall, 4.2% (n=570, weight HV005) of participants in the sample reported malaria complications. The results of the logistic regression revealed that children residing in urban settlements (aOR 0.37, 95% CI 0.37-0.37, p-value <0.001), children from the poorest class families (aOR 11.63, 95% CI 1.62-1.63, p-value 0.004), children from poorer class families (aOR 7.56, 95% CI 7.55-7.57, p-value <0.001), children from middle-class families (aOR 4.05, 95% CI 4.03-9.06, p-value <0.001), children from richer class families (aOR 1.22, 95% CI 2.21-2.23, p-value <0.001), children of mothers with primary education (aOR 0.42, 95% CI 2.32-4.112, p-value 0.001), children of mothers with secondary education (aOR 0.24, 95% CI 3.21-3.22, p-value <0.001), children of mothers with higher education (aOR 0.08, 95% CI 0.72-0.80, p-value <0.001), and children of the female gender (aOR 0.65, 95% CI 0.65-0.66, p-value <0.001) are all associated with severe malaria complications.

CONCLUSIONS

In conclusion, the study examined malaria complications in Nigerian children under five by residency. The findings imply that rural children are more likely to have serious malaria complications than urban children. This emphasizes the necessity for targeted malaria therapies in rural areas with limited healthcare access.

Design, Implementation, and Coordination of Malaria Therapeutic Efficacy Studies in Nigeria in 2018

Prior to 2018, malaria therapeutic efficacy studies (TESs) in Nigeria were implemented separately at different sites, as assigned by the National Malaria Elimination Program (NMEP). In 2018, however, the NMEP engaged the Nigerian Institute of Medical Research to coordinate the 2018 TESs in 3 of 14 sentinel sites with the objective of standardizing their conduct across all three sites: Enugu, Kano, and Plateau states in three of six geopolitical zones. Artemether-lumefantrine and artesunate-amodiaquine, the two first-line drugs for treatment of acute uncomplicated malaria in Nigeria, were tested in both Kano and Plateau states. In Enugu State, however, artemether-lumefantrine and dihydroartemisinin-piperaquine were the test drugs, with dihydroartemisinin-piperaquine being tested for potential inclusion in Nigerian treatment policy. The TES was conducted in 6-month to 8-year-old children and was funded by the Global Fund with additional support from the WHO. A multipartite core team comprised of the NMEP, the WHO, the U.S. Presidential Malaria Initiative, academia, and the Nigerian Institute of Medical Research was set up to oversee the execution of the 2018 TES. This communication reports best practices adopted to guide its coordination, and lessons learned during in the process, including applying developed standard operating procedures, powering the sample size adequately for each site to report independently, training the investigating team for fieldwork, facilitating stratification of decisions, determining efficiencies derived from monitoring and quality assessment, and optimizing logistics. The planning and coordination of the 2018 TES activities is a model of a consultative process for the sustainability of antimalarial resistance surveillance in Nigeria.

Efficacy and safety of pyronaridine-artesunate versus artemether-lumefantrine in the treatment of acute uncomplicated malaria in children in South-West Nigeria: an open-labelled randomized controlled trial

BACKGROUND

In Nigeria, declining responsiveness to artemether-lumefantrine (AL), the artemisinin-based combination therapy (ACT) of choice since 2005, has been reported. Pyronaridine-artesunate (PA) is a newer fixed-dose ACT recently prequalified by the WHO for the treatment of uncomplicated falciparum malaria. However, PA data from the Nigerian pediatric population is scarce. Therefore, the efficacy and safety of PA and AL using the WHO 28-day anti-malarial therapeutic efficacy study protocol in Ibadan, southwest Nigeria, were compared.

METHODS

In an open-labelled, randomized, controlled clinical trial, 172 children aged 3-144 months with a history of fever and microscopically confirmed uncomplicated Plasmodium falciparum malaria were enrolled in southwest Nigeria. Enrollees were randomly assigned to receive PA or AL at standard dosages according to body weight for 3 days. Venous blood was obtained for hematology, blood chemistry, and liver function tests on days 0, 3, 7, and 28 as part of the safety evaluation.

RESULTS

165 (95.9%) of the enrolled individuals completed the study. About half (52.3%; 90/172) of enrollees were male. Eighty-seven (50.6%) received AL, while 85 (49.4%) received PA. Day 28, adequate clinical and parasitological response for PA was 92.7% [(76/82) 95% CI 83.1, 95.9] and 71.1% [(59/83) 95% CI 60.4, 79.9] for AL (0.001). Fever and parasite clearance were similar in both groups. Two of six and eight of 24 parasite recurrences were observed among PA- and AL-treated children, respectively. PCR-corrected Day-28 cure rates for PA were 97.4% (76/78) and 88.1% (59/67) for AL (= 0.04) in the per-protocol population after new infections were censored. Hematological recovery at day 28 was significantly better among PA-treated patients (34.9% 2.8) compared to those treated with AL (33.1% 3.0) (0.002). Adverse events in both treatment arms were mild and similar to the symptoms of malaria infection. Blood chemistry and liver function tests were mostly within normal limits, with an occasional marginal rise.

CONCLUSION

PA and AL were well-tolerated. PA was significantly more efficacious than AL in both the PCR-uncorrected and PCR-corrected per-protocol populations during this study. The results of this study support the inclusion of PA in the anti-malarial treatment guidelines in Nigeria.

RETROSPECTIVE TRIAL REGISTRATION

Clinicaltrials.gov: NCT05192265.

Mutations in Pfcrt and Pfmdr1 genes of Plasmodium falciparum isolates from two sites in Northcentral and Southwest Nigeria

The ability of malaria parasites to develop resistance to antimalarial drugs has made it necessary to continuously survey malaria parasite populations for resistance markers. Mutations in specific malaria parasite genes confer resistance to antimalarial drugs. The study compared mutations in Pfcrt and Pfmdr1 genes of P. falciparum from two ecologically different areas of Nigeria. Plasmodium falciparum dried blood spots collected from New Bussa (Northcentral Nigeria) and Ijede (Southwest Nigeria) were analysed by PCR-RFLP for Pfcrt, K76 T, Pfmdr1, N86Y and Y184F mutations. Pfmdr1 copy number was determined by quantitative-PCR. A total of 145 blood spots [Ijede = 55; New Bussa = 90 blood spots] were analysed, but Pfcrt gene was successfully amplified in 144 samples while Pfmdr1 was amplified in 132 samples. Overall, prevalence of mutant forms of Pfcrt 76 T,Pfmdr1 86Y and 184F were 74.3% (95% CI: 66.4-81.2%), 18.2% (95% CI: 12.0-25.8%) and 35.6% (95% CI: 27.5-44.4%). The frequency of Pfcrt 76 T was similar in both study sites [Ijede: 81.8% (95%CI: 69.1-90.9%); New Bussa: 69.7% (95%CI: 59.0-79.0), p = 0.105]. However, the frequencies of Pfmdr1 86Y and 184F were significantly higher in Ijede (28.3% and 62.3%) than in New Bussa (11.4% and 17.7%), respectively (P < 0.05). Eight parasite genotypes based on three codons of the two genes were identified. The most frequent genotype was TNY 53(40.5%) while the least was KYF 1 (0.8%). The most frequent genotype in Ijede and New Bussa were TNF 18(34.0%) and TNY 40 (51.3%) respectively. The frequency of wild strain KNF in Ijede and New Bussa were 3 (5.7%) and 18 (23.1%), respectively. The distribution of the genotypes differed significantly by location. The genotypes with more than two or more mutations were more in Ijede 32 (60.4%) than in New Bussa 16 (20.5%) (p < 0.001). Amplification of Pfmdr1 copy number was not observed in the two study sites. The prevalence of Pfcrt 76 T was similar in both locations while Pfmdr1 86Y and 184F differed in both locations. Single nucleotide polymorphisms in the three codons assessed were more in Ijede than in New Bussa.

Polymorphisms in Plasmodium falciparum chloroquine resistance transporter (Pfcrt) and multidrug-resistant gene 1 (Pfmdr-1) in Nigerian children 10 years post-adoption of artemisinin-based combination treatments

The emergence and spread of Plasmodium falciparum parasites resistant to artemisinin derivatives and their partners in southeastern Asia threatens malaria control and elimination efforts, and heightens the need for an alternative therapy. We have explored the distribution of P. falciparum chloroquine resistance transporter (Pfcrt) and multidrug-resistant gene 1 (Pfmdr-1) haplotypes 10 years following adoption of artemisinin-based combination therapies in a bid to investigate the possible re-emergence of Chloroquine-sensitive parasites in Nigeria, and investigated the effect of these P. falciparum haplotypes on treatment outcomes of patients treated with artemisinin-based combination therapies. A total of 271 children aged <5 years with uncomplicated falciparum malaria were included in this study. Polymorphisms on codons 72-76 of the Pfcrt gene and codon 86 and 184 of Pfmdr-1 were determined using the high resolution melting assay. Of 240 (88.6%) samples successfully genotyped with HRM for Pfcrt, wildtype C72M74N75K76 (42.9%) and mutant C72I74E75T76 (53.8%) were observed. Also, wildtype N86Y184 (62.9%) and mutant N86F184 (21.1%), Y86Y184 (6.4%), and Y86F184 (0.4%) haplotypes of Pfmdr-1 were observed. Measures of responsiveness to ACTs were similar in children infected with P. falciparum crt haplotypes (C72I74E75T76 and C72M74N75K76) and major mdr-1 haplotypes (N86Y184, N86F184 and Y86Y184). Despite a 10 year gap since the malaria treatment policy changed to ACTs, over 50% of the P. falciparum parasites investigated in this study harboured the Chloroquine-resistant C72I74E75T76 haplotype, however this did not compromise the efficacy of artemisinin-based combination therapies. Should complete artemisinin resistance emerge from or spread to Nigeria, chloroquine might not be a good alternative therapy.

Mechanisms of artemether toxicity on single cardiomyocytes and protective effect of nanoencapsulation

BACKGROUND AND PURPOSE

The artemisinin derivative, artemether, has antimalarial activity with potential neurotoxic and cardiotoxic effects. Artemether in nanocapsules (NC-ATM) is more efficient than free artemether for reducing parasitaemia and increasing survival of Plasmodium berghei-infected mice. NCs also prevent prolongation of the QT interval of the ECG. Here, we assessed cellular cardiotoxicity of artemether and how this toxicity was prevented by nanoencapsulation.

EXPERIMENTAL APPROACH

Mice were treated with NC-ATM orally (120 mg·kg^-1 twice daily) for 4 days. Other mice received free artemether, blank NCs, and vehicle for comparison. We measured single-cell contraction, intracellular Ca²⁺ transient using fluorescent Indo-1AM Ca²⁺ dye, and electrical activity using the patch-clamp technique in freshly isolated left ventricular myocytes. The acute effect of free artemether was also tested on cardiomyocytes of untreated animals.

KEY RESULTS

Artemether prolonged action potentials (AP) upon acute exposure (at 0.1, 1, and 10 μM) of cardiomyocytes from untreated mice or after in vivo treatment. This prolongation was unrelated to blockade of K⁺ currents, increased Ca²⁺ currents or promotion of a sustained Na⁺ current. AP lengthening was abolished by the NCX inhibitor SEA-0400. Artemether promoted irregular Ca²⁺ transients during pacing and spontaneous Ca²⁺ events during resting periods. NC-ATM prevented all effects. Blank NCs had no effects compared with vehicle.

CONCLUSION AND IMPLICATIONS

Artemether induced NCX-dependent AP lengthening (explaining QTc prolongation) and disrupted Ca²⁺ handling, both effects increasing pro-arrhythmogenic risks. NCs prevented these adverse effects, providing a safe alternative to the use of artemether alone, especially to treat malaria.

Surveillance of the Efficacy of Artemisinin-Piperaquine in the Treatment of Uncomplicated Plasmodium falciparum Malaria Among Children Under 5 Years of Age in Est-Mono District, Togo, in 2017

Background

Malaria is a major public health concern in Togo. The Est-Mono district of Togo has a population of 150,000. Accordingly, the Guangzhou University of Chinese Medicine, China and the Ministry of Health and Social Security, Togo launched a nationwide Mass Drug Administration Project with artemisinin-piperaquine (AP) in Est-Mono. Before launching this project, the sensitivity test of AP was conducted in a general clinic in Elawagnon, Togo. With this background, we evaluated the efficacy and safety of AP for the treatment of uncomplicated falciparum malaria in children under the age of 5 years.

Methods

Children aged 6-59 months with uncomplicated falciparum malaria were enrolled in this study. The selected patients were treated with a combination regime of artemisinin-piperaquine. The patients were followed up for 28 days, during which signs of the following were observed for: the duration for fever clearance, parasitemia density, gametophyte generation, cure rate, hemoglobin level, and merozoite surface protein-2 (msp-2) polymorphism. The primary end point was a 28-day cure rate and polymerase chain reaction (PCR)-corrected reinfection and recrudescence. This research followed the standardized World Health Organization (WHO) protocol for the assessment of the efficacy of antimalarial drugs.

Results

A total of 91 children with uncomplicated falciparum malaria were enrolled in this study. Adequate clinical and parasitological responses (ACPRs) before and after PCR-correction were 66 (73%) and 90 (99%), respectively. The average hemoglobin level in the patient increased by 0.05 g/dl per day (p < 0.0001) after the treatment. The gametophyte generation did not decline at the beginning of the treatment; however, after 14 days, it declined (day 21: p < 0.05; day 28: p < 0.01). In the msp-2 polymorphism study of 24 children treated for parasite infection, one case of msp-2 with 3D7 haplotype and FC27 haplotype was noted, indicating its recrudescence, with a frequency of 4%. The remaining 23 cases could have been of reinfection, with a frequency of 96%. No serious adverse reactions occurred, and AP was well-tolerated by all patients.

Conclusion

Artemisinin-piperaquine was found to be an effective combination for treating uncomplicated falciparum malaria in children aged <5 years in Togo, and the drugs were well-tolerated. In Togo, Plasmodium falciparum remains sensitive to artemisinin-piperaquine, necessitating its trial in this region.

Clinical Trial Registration

Trial registration: ECGPHCM No. B2017-054-01; MHSST AVIS N° 0001/2016/CBRS du 07 janvier 2016. Registered 17 March 2014, http://www.chinadrugtrials.org.cn/eap/main.

Efficacy of artemether-lumefantrine and artesunate-amodiaquine as first line therapy of uncomplicated malaria in Burkina Faso, 11 years after policy change

Introduction

Artemether-lumefantrine (AL) and artesunate-amodiaquine (ASAQ) are the first line therapy of uncomplicated malaria in Burkina Faso. We assessed the treatment efficacy, tolerability of these drugs 11 years following its adoption as first line treatment.

Methods

In this opened randomized controlled trial carried out in 2016, participants with age over 6 months who consented to participate were randomly assigned treatment with artemether-lumefantrine or artesunate-amodiaquine and followed up for 28 days. Primary endpoint was the treatment efficacy over 28 days of follow up unadjusted by Polymerase chain reaction (PCR).

Results

Two hundred and eighty-one (281) participants were enrolled and the completion rate was 92.9%. No early treatment failure was found. Adequate clinical and parasitological responses were significantly higher in artesunate-amodiaquine group (97% versus 85.2%, p = 0.0008). On day 28, the risk of failure was 4 times higher in AL group 20.14%, 95% CI (13-30.47) against 5.16%, 95% CI (1.91-13.54) in ASAQ group. All treatments had a similar and good tolerability profile.

Conclusion

Eleven years following artemether-lumefantrine and artesunate-amodiaquine adoption as first line therapy for uncomplicated malaria in Burkina Faso, artemether-lumefantrine retained fairly good efficacy even though its efficacy fell below WHO threshold of 90% considering uncorrected outcome.

Clinical illness and outcomes in Nigerian children with persistent early-appearing anaemia following initiation of artemisinin-based combination treatments of uncomplicated falciparum malaria

In non-anaemic children with malaria, early-appearing anaemia (EAA) is common following artemisinin-based combination treatments (ACTs) and it may become persistent (PEAA). The factors contributing to and kinetics of resolution of the deficit in haematocrit from baseline (DIHFB) characteristic of ACTs-related PEAA were evaluated in 540 consecutive children with malaria treated with artemether-lumefantrine, artesunate-amodiaquine or dihydroartemisinin-piperaquine. Asymptomatic PEAA occurred in 62 children. In a multiple logistic regression model, a duration of illness ≤3 days before presentation, haematocrit <35% before and <25% one day after treatment initiation, drug attributable fall in haematocrit ≥6%, and treatment with dihydroartemisinin-piperaquine independently predicted PEAA. Overall, mean DIHFB was 5.7% (95% CI 4.8–6.6) 7 days after treatment initiation and was similar for all treatments. Time to 90% reduction in DIHFB was significantly longer in artemether-lumefantrine-treated children compared with other treatments. In a one compartment model, declines in DIHFB were monoexponential with overall mean estimated half-time of 3.9 days (95% CI 2.6–5.1), Cmax of 7.6% (95% CI 6.7–8.4), and Vd of 0.17 L/kg (95% CI 0.04–0.95). In Bland-Altman analyses, overall mean anaemia recovery time (AnRT) of 17.4 days (95% CI 15.5–19.4) showed insignificant bias with 4, 5 or 6 multiples of half-time of DIHFB. Ten children after recovery from PEAA progressed to late-appearing anaemia (LAA). Progression was associated with female gender and artesunate-amodiaquine treatment. Asymptomatic PEAA is common following ACTs. PEAA or its progression to LAA may have implications for case and community management of anaemia and for anaemia control efforts in sub-Saharan Africa where ACTs have become first-line antimalarials.

Trial registration: Pan Africa Clinical Trial Registration PACTR201709002064150, 1 March 2017 http://www.pactr.org

Declining responsiveness of childhood Plasmodium falciparum infections to artemisinin-based combination treatments ten years following deployment as first-line antimalarials in Nigeria

Background

The development and spread of artemisinin-resistant Plasmodium falciparum malaria in Greater Mekong Subregion has created impetus for continuing global monitoring of efficacy of artemisinin-based combination therapies (ACTs). This post analyses is aimed to evaluate changes in early treatment response markers 10 years after the adoption of ACTs as first-line treatments of uncomplicated falciparum malaria in Nigeria.

Methods

At 14 sentinel sites in six geographical areas of Nigeria, we evaluated treatment responses in 1341 children under 5 years and in additional 360 children under 16 years with uncomplicated malaria enrolled in randomized trials of artemether-lumefantrine versus artesunate-amodiaquine at 5-year interval in 2009–2010 and 2014–2015 and at 2-year interval in 2009–2010 and 2012–2015, respectively after deployment in 2005.

Results

Asexual parasite positivity 1 day after treatment initiation (APPD1) rose from 54 to 62% and 2 days after treatment initiation from 5 to 26% in 2009–2010 to 2014–2015 (P = 0.002 and P <  0.0001, respectively). Parasite clearance time increased significantly from 1.6 days (95% confidence interval [CI]: 1.55–1.64) to 1.9 days (95% CI, 1.9–2.0) and geometric mean parasite reduction ratio 2 days after treatment initiation decreased significantly from 11 000 to 4700 within the same time period (P <  0.0001 for each). Enrolment parasitaemia > 75 000 μl^− 1, haematocrit > 27% 1 day post-treatment initiation, treatment with artemether-lumefantrine and enrolment in 2014–2015 independently predicted APPD1. In parallel, Kaplan-Meier estimated risk of recurrent infections by day 28 rose from 8 to 14% (P = 0.005) and from 9 to 15% (P = 0.02) with artemether-lumefantrine and artesunate-amodiaquine, respectively. Mean asexual parasitaemia half-life increased significantly from 1.1 h to 1.3 h within 2 years (P <  0.0001).

Conclusions

These data indicate declining parasitological responses through time to the two ACTs may be due to emergence of parasites with reduced susceptibility or decrease in immunity to the infections in these children.

Trial registration

Pan African Clinical Trial Registration PACTR201508001188143, 3 July 2015; PACTR201508001191898, 7 July 2015 and PACTR201508001193368, 8 July 2015 PACTR201510001189370, 3 July 2015; PACTR201709002064150, 1 March 2017; https://www.pactr.samrca.ac.za

Electronic supplementary material

The online version of this article (10.1186/s40249-019-0577-x) contains supplementary material, which is available to authorized users.

Preference for Artemisinin-based combination therapy among healthcare providers, Lokoja, North-Central Nigeria

Background

In Nigeria, Artemisinin-based Combination Therapy (ACT) is the recommended first line antimalarial medicine for uncomplicated malaria. However, health care providers still continue the use of less efficacious medicines such as Sulphadoxine-pyrimethamine and chloroquine. We therefore determined preference for ACT (PFA) and factors associated with PFA among healthcare providers (HCP) in Lokoja, North-Central Nigeria as well as assessed healthcare providers' knowledge of malaria case management.

Methods

We conducted a cross-sectional study among physicians, nurses, pharmacists, community health officers (CHOs), community health extension workers (CHEWs) and, patent and proprietary medicine vendors (PPMVs). Interviewer-administered questionnaires were administered to collect data on respondents' characteristics, previously received malaria case management training and knowledge of malaria treatment. Knowledge scores ≥3 were categorised as good, maximum obtainable being 5.

Results

Of the 404 respondents, 214 (53.0%) were males. Overall, 219 (54.2%) respondents who received malaria case management training  included PPMVs: 79 (65.8%), CHEWs: 25 (64.1%), CHOs: 5 (55.6%), nurses: 72 (48.7%), physicians: 35 (47.3%) and pharmacists: 3 (23.1%). Overall, 202 (50.0%) providers including physicians: 69 (93.2%), CHO: 8 (88.9%), CHEWs: 33 (84.6%), pharmacists: 8 (61.5%), nurses: 64 (43.2%) and PPMVs: 20 (16.5%), had good knowledge of malaria treatment guidelines. Overall, preference for ACT among healthcare providers was 39.6%. Physicians: 50 (67.6%), pharmacists: 7 (59.3%) CHOs: 5 (55.6%), CHEWS: 16 (41.0%), nurses: 56 (37.8%) and PPMV: 24 (19.8%) had PFA. Receiving malaria case management training (adjusted odds ratio [aOR]) = 2.3; CI = 1.4 - 3.7) and having good knowledge of malaria treatment (aOR = 4.0; CI = 2.4 - 6.7) were associated with PFA.

Conclusions

Overall preference for ACT use was low among health care providers in this study. Preference for ACTs and proportion of health workers with good knowledge of malaria case management were even lower among PPMVs who had highest proportion of those who received malaria case management training. We recommend evaluation of current training quality, enhanced targeted training, follow-up supportive supervision of PPMVs and behavior change communication on ACT use.

Efficacy of Artemisinin-Based Combination Treatments of Uncomplicated Falciparum Malaria in Under-Five-Year-Old Nigerian Children Ten Years Following Adoption as First-Line Antimalarials

The efficacies of 3-day regimens of artemether-lumefantrine (AL), artesunate-amodiaquine (AA), and dihydroartemisinin-piperaquine (DHP) were evaluated in 910 children < 5 years old with uncomplicated malaria from six geographical areas of Nigeria. Parasite positivity 1 day and Kaplan-Meier estimated risk of persistent parasitemia 3 days after therapy initiation were both significantly higher, and geometric mean parasite reduction ratio 1 day after treatment initiation (PRRD1) was significantly lower in AL-treated children than in AA- and DHP-treated children. No history of fever, temperature > 38°C, enrollment parasitemia > 75,000 μL-1, and PRRD1 < 5,000 independently predicted persistent parasitemia 1 day after treatment initiation. Parasite clearance was significantly faster and risk of reappearance of asexual parasitemia after initial clearance was significantly lower in DHP-treated children. Overall, day 42 polymerase chain reaction-corrected efficacy was 98.3% (95% confidence interval [CI]: 96.1-100) and was similar for all treatments. In a non-compartment model, declines of parasitemias were monoexponential with mean terminal elimination half-life of 1.3 hours and unimodal frequency distribution of half-lives. All treatments were well tolerated. In summary, all three treatments evaluated remain efficacious treatments of uncomplicated malaria in young Nigerian children, but DHP appears more efficacious than AL or AA.

Efficacy of artesunate-amodiaquine, dihydroartemisinin-piperaquine and artemether-lumefantrine for the treatment of uncomplicated Plasmodium falciparum malaria in Maradi, Niger

BACKGROUND

Malaria endemic countries need to assess efficacy of anti-malarial treatments on a regular basis. Moreover, resistance to artemisinin that is established across mainland South-East Asia represents today a major threat to global health. Monitoring the efficacy of artemisinin-based combination therapies is of paramount importance to detect as early as possible the emergence of resistance in African countries that toll the highest burden of malaria morbidity and mortality.

METHODS

A WHO standard protocol was used to assess efficacy of the combinations artesunate-amodiaquine (AS-AQ Winthrop®), dihydroartemisinin-piperaquine (DHA-PPQ, Eurartesim®) and artemether-lumefantrine (AM-LM, Coartem®) taken under supervision and respecting pharmaceutical recommendations. The study enrolled for each treatment arm 212 children aged 6-59 months living in Maradi (Niger) and suffering with uncomplicated falciparum malaria. The Kaplan-Meier 42-day PCR-adjusted cure rate was the primary outcome. A standardized parasite clearance estimator was used to assess delayed parasite clearance as surrogate maker of suspected artemisinin resistance.

RESULTS

No early treatment failures were found in any of the study treatment arms. The day-42 PCR-adjusted cure rate estimates were 99.5, 98.4 and 99.0% in the AS-AQ, DHA-PPQ and AM-LM arms, respectively. The reinfection rate (expressed also as Kaplan-Meier estimates) was higher in the AM-LM arm (32.4%) than in the AS-AQ (13.8%) and the DHA-PPQ arm (24.9%). The parasite clearance rate constant was 0.27, 0.26 and 0.25 per hour for AS-AQ, DHA-PPQ and AM-LM, respectively.

CONCLUSIONS

All the three treatments evaluated largely meet WHO criteria (at least 95% efficacy). AS-AQ and AL-LM may continue to be used and DHA-PPQ may be also recommended as first-line treatment for uncomplicated falciparum malaria in Maradi. The parasite clearance rate were consistent with reference values indicating no suspected artemisinin resistance. Nevertheless, the monitoring of anti-malarial drug efficacy should continue. Trial registration details Registry number at ClinicalTrial.gov: NCT01755559.

Factors contributing to anaemia after uncomplicated falciparum malaria in under five year-old Nigerian children ten years following adoption of artemisinin-based combination therapies as first-line antimalarials

Background

Artemisinin-based combination therapies (ACTs) have remained efficacious treatments of acute falciparum malaria in many endemic areas but there is little evaluation of factors contributing to the anaemia of acute falciparum malaria following long term adoption of ACTs as first-line antimalarials in African children.

Methods

Malarious <5 year-olds randomized to artemether-lumefantrine, artesunate-amodiaquine or dihydroartemisinin-piperaquine treatments were followed up clinically for 6 weeks. Anaemia was defined as haematocrit <30%; Malaria-attributable fall in haematocrit (MAFH) as the difference between haematocrit 28–42 days post- and pre-treatment; Total MAFH (TMAFH) as the difference between days 28–42 haematocrit and the lowest haematocrit recorded in the first week post-treatment initiation; Drug-attributable fall in haematocrit (DAFH) as the difference between MAFH and TMAFH; Early appearing anaemia (EAA) as haematocrit <30% occurring within 1 week in children with normal haematocrit pre-treatment. Predictors of anaemia pre-treatment, EAA, MAFH or DAFH >4% were evaluated by stepwise multiple logistic regression models. Survival analysis and kinetics of DAFH were evaluated by Kaplan-Meier estimator and non-compartment model, respectively.

Results

Pre-treatment, 355 of 959 children were anaemic. Duration of illness >2 days and parasitaemia ≤10,000 μL⁻¹ were independent predictors of anaemia pre-treatment. EAA occurred in 301 of 604 children. Predictors of EAA were age ≤ 15 months, history of fever pre-treatment and enrolment haematocrit ≤35%. The probabilities of progression from normal haematocrit to EAA were similar for all treatments. MAFH >4% occurred in 446 of 694 children; its predictors were anaemia pre-treatment, enrolment parasitaemia ≤50,000 μL⁻¹, parasitaemia one day post-treatment initiation and gametocytaemia. DAFH >4% occurred in 334 of 719 children; its predictors were history of fever pre-and fever 1 day post-treatment initiation, haematocrit ≥37%, and parasitaemia >100,000 μL⁻¹. In 432 children, declines in DAFH deficits were monoexponential with overall estimated half-time of 2.2d (95% CI 1.9–2.6). Area under curve of deficits in DAFH versus time and estimated half-time were significantly higher in non-anaemic children indicating greater loss of haematocrit in these children.

Conclusion

After ten years of adoption of ACTs, anaemia is common pre-and early post-treatment, falls in haematocrit attributable to a single infection is high, and DAFH >4% is common and significantly lower in anaemic compared to non-anaemic Nigerian children.

Trial registration

Pan African Clinical Trial Registry (PACTR) [PACTR201709002064150, 1 March 2017].

Demand-related factors influencing caregivers' awareness of malaria tests and health workers' testing practices, in Makarfi, Nigeria

Background

Despite the World Health Organization’s recommendation of malaria test-treat strategy, which is the treatment of parasitological confirmed malaria cases with anti-malarials, presumptive diagnosis of malaria remains fairly common in Nigeria. The reasons for this have not been established in Makarfi, Nigeria, despite the high burden of malaria in the area. A study was conducted among caregivers of febrile children less than 5 years presenting for treatment to understand their awareness of malaria diagnostic testing and being offered testing by clinicians, the determinants of these outcomes, and caregivers’ perspectives of health workers’ testing practices.

Methods

Using mixed-methods, data was combined from sub-analysis of cross-sectional survey data (n = 295) and focus group discussions (n = 4) with caregivers conducted in Makarfi General Hospital (Kaduna State, Nigeria) and surrounding communities in 2011. Bivariate and multivariate analysis of the quantitative survey data was conducted to examine associations of caregivers’ sociodemographic characteristics with testing awareness and having ever been offered testing. Transcripts from focus group discussions (FGD) were analysed for emerging themes related to caregivers’ perspectives on malaria testing.

Results

Among surveyed caregivers who were predominantly female (81.7%), not formally educated (72.5%), and were housewives (68.8%); only 5.3% were aware of any diagnostic testing for malaria, and only 4.3% had ever been offered a malaria test by a health worker. Having at least a primary level education (adjusted odds ratio [aOR] 20.3, 95% CI 4.5–92.1) and living within 5 km of the hospital (aOR 4.3, 95% CI 1.5–12.5) were determinants of awareness of malaria testing. Also, these were determinants of previously having been offered a test (aOR 9.9, 95% CI 2.1–48.7; and aOR 4.0, 95% CI 1.1–14.7). FGD showed many caregivers believed that malaria testing was for severe illness only, and that proximity to a health facility and cost of treatment influenced the seeking and receiving of care.

Conclusions

Uptake of malaria testing prior to treatment can be improved by increasing its awareness and addressing misunderstandings among caregivers, promoting testing practices among health workers, and availing caregivers living farther from health centres alternative opportunities for community case management of febrile illnesses.

Efficacy of Artesunate/Amodiaquine in the Treatment of Uncomplicated Malaria among Children in Ghana

The declining efficacy of chloroquine in the early 2000s in Ghana led to its replacement with artesunate/amodiaquine (AS/AQ) combination as first-line drug for treating uncomplicated malaria in 2005. Since then efficacy studies have been ongoing in the country to provide continuous data on the efficacy of AS/AQ and other alternative antimalarials (artemether/lumefantrine and dihyroartemisinin/piperaquine combinations) introduced in 2008. In vivo AS/AQ efficacy studies were conducted between June and October 2014 among children aged 6 months to 14 years, in two sentinel sites representing the forest and coastal zones of the country. The 2009 World Health Organization protocol for monitoring antimalarial drug efficacy was used in these studies. The studies showed an overall cumulative polymerase chain reaction-corrected day 28 cure rate of 97.2% (95% confidence interval [CI]: 93.6-99.1): 97.7% (95% CI: 92.0-99.7) within the forest zone and 96.7% (95% CI: 90.7-99.3) within the coastal zone (P = 0.686). Prevalence of fever declined from 100% to < 4% after first day of treatment in both ecological zones. All children in the coastal zone had cleared parasites by day 2. Three children (3.2%) in the forest zone were parasitemic on day 2, whereas one child was parasitemic on day 3. Gametocytemia was absent in both zones after day 14, and mean hemoglobin concentration significantly increased from 10.3 g/dL (95% CI: 10.1-10.5) on day 0 to 11.8 g/dL (95% CI: 11.6-12.0) on day 28. We conclude that AS/AQ combination remains efficacious in the treatment of uncomplicated malaria in Ghana.

Haemoglobin changes and risk of anaemia following treatment for uncomplicated falciparum malaria in sub-Saharan Africa

Background

Anaemia is common in malaria. It is important to quantitate the risk of anaemia and to distinguish factors related to the natural history of disease from potential drug toxicity.

Methods

Individual-patient data analysis based on nine randomized controlled trials of treatments of uncomplicated falciparum malaria from 13 sub-Saharan African countries. Risk factors for reduced haemoglobin (Hb) concentrations and anaemia on presentation and after treatment were analysed using mixed effect models.

Results

Eight thousand eight hundred ninety-seven patients (77.0% <5 years-old) followed-up through 28 days treated with artemisinin combination therapy (ACT, 90%, n = 7968) or non-ACT. At baseline, under 5’s had the highest risk of anaemia (77.6% vs. 32.8%) and higher parasitaemia (43,938 μl) than older subjects (2784 μl). Baseline anaemia increased the risk of parasitological recurrence.

Hb began to fall after treatment start. In under 5’s the estimated nadir was ~35 h (range 29–48), with a drop of −12.8% from baseline (from 9.8 g/dl to 8.7 g/dl, p = 0.001); in under 15’s, the mean Hb decline between day 0–3 was −4.7% (from 9.4 to 9.0 g/dl, p = 0.001). The degree of Hb loss was greater in patients with high pre-treatment Hb and parasitaemia and with slower parasite reduction rates, and was unrelated to age. Subsequently, Hb increased linearly (+0.6%/day) until day 28, to reach +13.8% compared to baseline.

Severe anaemia (<5 g/dl, 2 per 1000 patients) was transient and all patients recovered after day 14, except one case of very severe anaemia associated with parasite recurrence at day 28.

There was no systematic difference in Hb concentrations between treatments and no case of delayed anaemia.

Conclusion

On presentation with acute malaria young children with high parasitaemia have the highest risk of anaemia. The majority of patients experience a drop in Hb while on treatment as early as day 1–2, followed by a linear increase through follow-up. The degree of the early Hb dip is determined by pre-treatment parasitaemia and parasite clearance rates. Hb trends and rick of anaemia are independent of treatment.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-017-2530-6) contains supplementary material, which is available to authorized users.

Anaemia following Artemisinin-Based Combination Treatments of Uncomplicated Plasmodium falciparum Malaria in Children: Temporal Patterns of Haematocrit and the Use of Uncomplicated Hyperparasitaemia as a Model for Evaluating Late-Appearing Anaemia

BACKGROUND

In severe malaria, intravenous artesunate may cause delayed haemolytic anaemia but there has been little evaluation of the propensity of oral artemisinin-based combination treatments (ACTs) to cause late-appearing anaemia.

METHODS

The frequency of anaemia (haematocrit <30%), and temporal changes in haematocrit were evaluated in 1,191 malarious children following ACTs. "Haematocrit conservation" was evaluated by using the fall in haematocrit/1,000 asexual parasites cleared from the peripheral blood (FIH/1,000 asexual parasites cpb), and the ratio of the average haematocrit (on the first 3 days of starting treatment):total parasitaemia cleared.

RESULTS

The frequency of anaemia decreased significantly following treatment. FIH/1,000 asexual parasites cpb, average haematocrit:total parasitaemia cleared, and mean haematocrit 5 weeks after treatment began were significantly lower in hyperparasitaemic children than in children without hyperparasitaemia, suggesting haematocrit conservation during treatment followed later by a loss of haematocrit. Asymptomatic late-appearing anaemia occurred in 6% of the children.

CONCLUSION

Artesunate-amodiaquine and artemether-lumefantrine contribute to haematocrit conservation at high parasitaemias but may cause late-appearing anaemia.

Therapeutic efficacy and effects of artemisinin-based combination treatments on uncomplicated Plasmodium falciparum malaria -associated anaemia in Nigerian children during seven years of adoption as first-line treatments

BACKGROUND

Artemisinin-based combination treatments (ACTs) are the first-line treatments of uncomplicated Plasmodium falciparum malaria in many endemic areas but there are few evaluation of their efficacy in anaemic malarious children.

METHODS

Therapeutic efficacy of 3-day regimens of artesunate-amodiaquine and artemether-lumefantrine was evaluated in 437 anaemic and 909 non-anaemic malarious children following treatment during a seven-year period (2008-2014). Patterns of temporal changes in haematocrit were classified based on haematocrit values <30% and ≥30%. Kinetics of the disposition of the deficit in haematocrit from 30% following treatment were evaluated using a non-compartment model.

RESULTS

PCR-corrected parasitological efficacy 28 days after start of treatment was significantly higher in artesunate-amodiaquine- compared to artemether-lumefantrine-treated children [97% (95%CI: 92.8-100) versus 96.4% (95%CI: 91.3-99.4), P = 0.02], but it was similar in non-anaemic and anaemic children. Fall in haematocrit/1 000 asexual parasites cleared from peripheral blood was significantly greater at lower compared to higher parasitaemias (P < 0.0001), and in non-anaemic compared to anaemic children (P = 0.007). In anaemic children at presentation, mean anaemia recovery time (AnRT) was 15.4 days (95%CI: 13.3-17.4) and it did not change over the years. Declines in haematocrit deficits from 30% were monoexponential with mean estimated half-time of 1.4 days (95%CI: 1.2-1.6). Anaemia half-time (t½anaemia) correlated positively with AnRT in the same patients (r = 0.69, P < 0.0001). Bland-Altman analysis of 10 multiples of t½anaemia and AnRT showed narrow limit of agreement with insignificant bias (P = 0.07) suggesting both can be used interchangeably in the same patients.

CONCLUSIONS

Artesunate-amodiaquine and artemether-lumefantrine remain efficacious treatments of uncomplicated P. falciparum infections in non-anaemic and anaemic Nigerian children in the last 7 years of adoption as first-line treatments. These ACTs may also conserve haematocrit at high parasitaemias and in anaemic children.

TRIALS REGISTRATION

Pan African Clinical Trial Registry PACTR201508001188143 , 3 July 2015; PACTR201510001189370 , 3 July 2015; PACTR201508001191898 , 7 July 2015 and PACTR201508001193368 , 8 July 2015.

Early rising asexual parasitaemia in Nigerian children following a first dose of artemisinin-based combination treatments of falciparum malaria

Background

Early rising asexual parasitaemia (ERAP), initially defined as ‘an increase in the parasite count over the baseline pre-treatment level during the first 24 h of treatment’ of falciparum malaria with artemisinin derivatives is well documented, but there is no characterization of its risk factors, kinetics, molecular features or relationship to late-appearing anaemia (LAA) in acute falciparum malaria in African children following oral artemisinin-based combination therapies (ACTs).

Methods

ERAP was defined as ≥5% increase in pre-treatment parasitaemia within 8 h of initiating treatment. Parasitaemia was quantified pre-treatment and 1–2 hourly for 8 h, and less frequently thereafter for 6 weeks following randomized treatment of acutely malarious children with artesunate-amodiaquine, artemether-lumefantrine or dihydroartemisinin-piperaquine. Risk factors were determined by stepwise multiple logistic regression model. Kinetics of release into and of elimination of asexual parasites and DNA clones from peripheral blood were evaluated by method of residuals and non-compartment model, respectively. Parasite population changes were evaluated morphologically and by molecular genotyping.

Results

ERAP occurred in 205 of 416 children. A parasitaemia <100,000/μL and parasitaemia 1 day post-treatment initiation were independent predictors of ERAP. In children with ERAP: mean and peak time of increase in parasitaemia were 105.6% (95% CI 81–130.1) and 2.5 h (95% CI 2.2–2.7), respectively. Mean lag time, half-time and rate constant of release were 0.2 h (95% CI 0.2–0.3), 1 h (95% CI 0.9–1.1), and 0.9 h⁻¹ (95% CI 0.8–1), respectively. Schizonts and young gametocytes were seen only in peripheral blood of few children with ERAP. In age-, gender-, baseline parasitaemia- and treatment-matched children with and without ERAP, parasite DNA clearance time and area under curve of number of DNA clones versus time were significantly higher in children with ERAP indicating peripheral retention of released parasites followed by elimination. DNA clone elimination was monoexponential.

Conclusion

ERAP is common, occurs rapidly as first order process and may be due to mobilization of parasites from deep tissue following a first dose of ACTs of acute childhood falciparum malaria.

Trials registration

Pan African Clinical Trial Registry PACTR201508001188143, 3 July 2015; PACTR201510001189370, 3 July 2015; PACTR201508001191898, 7 July 2015 and PACTR201508001193368, 8 July 2015.

Assessment of submicroscopic infections and gametocyte carriage of Plasmodium falciparum during peak malaria transmission season in a community-based cross-sectional survey in western Kenya, 2012

Background

Although malaria control intervention has greatly decreased malaria morbidity and mortality in many African countries, further decline in parasite prevalence has stagnated in western Kenya. In order to assess if malaria transmission reservoir is associated with this stagnation, submicroscopic infection and gametocyte carriage was estimated. Risk factors and associations between malaria control interventions and gametocyte carriage were further investigated in this study.

Methods

A total of 996 dried blood spot samples were used from two strata, all smear-positives (516 samples) and randomly selected smear-negatives (480 samples), from a community cross-sectional survey conducted at peak transmission season in 2012 in Siaya County, western Kenya. Plasmodium falciparum parasite presence and density were determined by stained blood smear and by 18S mRNA transcripts using nucleic acid sequence-based amplification assay (NASBA), gametocyte presence and density were determined by blood smear and by Pfs25 mRNA-NASBA, and gametocyte diversity by Pfg377 mRNA RT-PCR and RT-qPCR.

Results

Of the randomly selected smear-negative samples, 69.6 % (334/480) were positive by 18S-NASBA while 18S-NASBA detected 99.6 % (514/516) smear positive samples. Overall, 80.2 % of the weighted population was parasite positive by 18S-NASBA vs 30.6 % by smear diagnosis and 44.0 % of the weighted population was gametocyte positive by Pfs25-NASBA vs 2.6 % by smear diagnosis. Children 5–15 years old were more likely to be parasitaemic and gametocytaemic by NASBA than individuals >15 years old or children <5 years old while gametocyte density decreased with age. Anaemia and self-reported fever within the past 24 h were associated with increased odds of gametocytaemia. Fever was also positively associated with parasite density, but not with gametocyte density. Anti-malarial use within the past 2 weeks decreased the odds of gametocytaemia, but not the odds of parasitaemia. In contrast, recent anti-malarial use was associated with lowered parasite density, but not the gametocyte density. Use of ITNs was associated with lower odds for parasitaemia in part of the study area with a longer history of ITN interventions. In the same part of study area, the odds of having multiple gametocyte alleles were also lower in individuals using ITNs than in those not using ITNs and parasite density was positively associated with gametocyte diversity.

Conclusion

A large proportion of submicroscopic parasites and gametocytes in western Kenya might contribute to the stagnation in malaria prevalence, suggesting that additional interventions targeting the infectious reservoir are needed. As school aged children and persons with anaemia and fever were major sources for gametocyte reservoir, these groups should be targeted for intervention and prevention to reduce malaria transmission. Anti-malarial use was associated with lower parasite density and odds of gametocytaemia, but not the gametocyte density, indicating a limitation of anti-malarial impact on the transmission reservoir. ITN use had a protective role against parasitaemia and gametocyte diversity in western Kenya.

Electronic supplementary material

The online version of this article (doi:10.1186/s12936-016-1482-4) contains supplementary material, which is available to authorized users.

Therapeutic efficacy and effects of artesunate-amodiaquine and artemether-lumefantrine on malaria-associated anaemia in Nigerian children aged two years and under

BACKGROUND

Artemisinin-based combination therapies are recommended as first-line treatments for uncomplicated falciparum malaria, but there is little evaluation of their efficacy and effects on uncomplicated malaria-associated anaemia in children aged 2 years and under.

METHODS

Parasitological efficacy and effects on malaria-associated anaemia were evaluated in 250 malarious children aged 2 years and under, and efficacy was evaluated in 603 malarious children older than two but younger than 5 years of age following treatment with artesunate-amodiaquine (AA) or artemether-lumefantrine (AL). Kinetics of the disposition of parasitaemia following treatment were evaluated using a non-compartment model. Late-appearing anaemia (LAA) was diagnosed using the following criteria: clearance of parasitaemia, fever and other symptoms occurring within 7 days of starting treatment, adequate clinical and parasitological response on days 28-42, haematocrit (HCT) ≥ 30 % at 1 and/or 2 weeks, a fall in HCT to < 30 % occurring at 3-6 weeks, absence of concomitant illness at 1-6 weeks, and absence of asexual parasitaemia detected using both microscopy and polymerase chain reaction (PCR) at 1-6 weeks.

RESULTS

Overall, in children aged 2 years and under, the PCR-corrected parasitological efficacy was 97.2 % (95 % CI 92.8-101.6), which was similar for both treatments. In children older than 2 years, parasitological efficacy was also similar for both treatments, but parasite prevalence 1 day after treatment began was significantly higher, and fever and parasite clearance times were significantly faster in the AA-treated children compared with the AL-treated children. Declines in parasitaemia were monoexponential with an estimated elimination half-time of 1 h. Elimination half-times were similar for both treatments. In children aged 2 years and under who were anaemic at presentation, the mean anaemia recovery time was 12.1 days (95 % CI 10.6-13.6, n = 127), which was similar for both treatments. Relatively asymptomatic LAA occurred in 11 children (4.4 %) aged 2 years and under, the recovery from which was uneventful.

CONCLUSION

This study showed that AA and AL are efficacious treatments for uncomplicated falciparum malaria in Nigerian children aged 2 years and under, and that AA clears parasitaemia and fever significantly faster than AL in children older than 2 years. Both treatments may cause a relatively asymptomatic LAA with uneventful recovery in a small proportion of children aged 2 years and under.

TRIALS REGISTRATION

Pan African Clinical Trial Registry PACTR201508001188143, 3 July 2015; PACTR201510001189370, 3 July 2015; PACTR201508001191898, 7 July 2015 and PACTR201508001193368, 8 July 2015  http://www.pactr.org .

Therapeutic efficacy trial of artemisinin-based combination therapy for the treatment of uncomplicated malaria and investigation of mutations in k13 propeller domain in Togo, 2012-2013

BACKGROUND

Since 2005, the Togo National Malaria Control Programme has recommended two different formulations of artemisinin-based combination therapy (ACT), artesunate-amodiaquine (ASAQ) and artemether-lumefantrine (AL), for the treatment of uncomplicated malaria. Regular efficacy monitoring of these two combinations is conducted every 2 or 3 years. This paper reports the latest efficacy assessment results and the investigation of mutations in the k13 propeller domain.

METHODS

The study was conducted in 2012-2013 on three sentinel sites of Togo (Lomé, Sokodé and Niamtougou). Children aged 6-59 months, who were symptomatically infected with Plasmodium falciparum, were treated with either AL (Coartem(®), Novartis Pharma, Switzerland) or ASAQ (Co-Arsucam(®), Sanofi Aventis, France). The WHO standard protocol for anti-malarial treatment evaluation was used. The primary end-point was 28-day adequate clinical and parasitological response (ACPR), corrected to exclude reinfection using polymerase-chain reaction (PCR) genotyping.

RESULTS

A total of 523 children were included in the study. PCR-corrected ACPR was 96.3-100 % for ASAQ and 97-100 % for AL across the three study sites. Adverse events were negligible: 0-4.8 % across all sites, for both artemisinin-based combinations. Upon investigation of mutations in the k13 propeller domain, only 9 (1.8 %) mutations were reported, three in each site. All mutant parasites were cleared before day 3. All day 3 positive patients were infected with k13 wild type parasites.

CONCLUSIONS

The efficacy of AL and ASAQ remains high in Togo, and both drugs are well tolerated. ASAQ and AL would be recommended for the treatment of uncomplicated malaria in Togo.

Clinical illness and outcomes in Nigerian children with late-appearing anaemia after artemisinin-based combination treatments of uncomplicated falciparum malaria

Background

Late-appearing anaemia (LAA) following treatment with artemisinins for severe malaria has been reported and well described, but there are limited clinical and parasitological data on LAA in African children with uncomplicated falciparum malaria following oral artemisinin-based combination therapies (ACTs).

Methods

This was an open label study with the main objectives of evaluating the clinical features, the risk factors for, the temporal changes in haematocrit and the outcomes of a LAA in malarious children treated with artesunate-amodiaquine (AA), artemether-lumefantrine (AL) or dihydroartemisinin-piperaquine (DHP). The diagnosis of LAA was made using the criteria: clearance of parasitaemia, fever and other symptoms within 1 week of commencing treatment; adequate clinical and parasitological response at 4–6 weeks after treatment began; haematocrit ≥30 % 1 and/or 2 weeks after treatment began; and haematocrit <30 %, parasite negativity by microscopy and polymerase chain reaction and absence of concomitant illness 3–6 weeks after treatment began.

Results

LAA occurred in 84 of 609 children, was mild, moderate or severe in 77, 6 or 1 child, respectively and was relatively asymptomatic. Mean time elapsing from commencement of treatment to LAA was 27.1 days (95 % CI 25.3–28.9). In a multivariate analysis, an age <3 years (adjusted odd ratio [AOR] = 2.6, 95 % CI 1.3–5.2, P = 0.005), fever 1 day after treatment began (AOR = 3.8, 95 % CI 1.8–8.2, P < 0.0001), haematocrit <25 % at presentation (AOR = 2.2, 95 % CI 1.3–3.7, P = 0.003), haematocrit <30 % 1 day after treatment began (AOR = 2.1, 95 % CI 1.0–4.3, P = 0.04), parasite reduction ratio >10⁴ 2 days after treatment began (AOR = 2.1, 95 % CI 1.1–3.9, P = 0.03) and spleen enlargement at presentation (AOR = 2.0, 95 % CI 1.1–3.9, P < 0.0001) were independent predictors of LAA. During 6 weeks of follow-up, uneventful recovery from anaemia occurred in 56 children [mean recovery time of 11.8 days (95 % CI 10.3–13.3)]. The only independent predictor of failure of recovery was LAA occurring 4 weeks after starting treatment (AOR = 7.5, 95 % CI 2.5–22.9, P < 0.0001).

Conclusion

A relatively asymptomatic LAA with uneventful recovery can occur in young malarious children following ACTs. Its occurrence may have implications for case and community management of anaemia and for anaemia control efforts in sub–Saharan Africa where ACTs have become first-line antimalarials.

Trials registration

Pan African Clinical Trial Registry PACTR201508001188143, 3 July 2015; PACTR201510001189370, 3 July 2015; PACTR201508001191898, 7 July 2015 and PACTR201508001193368, 8 July 2015 http://www.pactr.org.

Temporal changes in haematocrit following artemisinin-based combination treatments of uncomplicated falciparum malaria in children

Background

Artemisinin-based combination treatments (ACTs) or intravenous artesunate are used in over 100 countries for uncomplicated or severe falciparum malaria. Although intravenous artesunate may cause delayed haemolytic anaemia, there is little evaluation of the temporal changes in haematocrit following ACTs.

Methods

Clinical and parasitological parameters were measured before and following treatment of uncomplicated falciparum malaria in children with artesunate-amodiaquine (AA) or artemether-lumefantrine (AL) over 6-weeks. Changes in haematocrit were characterized in individual patients based on a haematocrit <30 % or ≥30 % before and following treatment. Kinetics of the deficit in haematocrit from <30 % until attainment of ≥30 % were estimated by a non-compartment model.

Results

In 248 of 1180 children eligible for evaluation, common temporal patterns were: no change or increase in haematocrit from ≥ 30 % [50 % of patients], haematocrit >30 % at presentation declining to <30 % within 2 weeks (early monophasic fall) [19 % of patients], and haematocrit <30 % at presentation increasing to ≥ 30 % [23 % of patients]. Haematocrit >30 % at presentation declining to <30 %, 3–5 weeks later (late monophasic fall) occurred in 7 children (3 %). Fall in haematocrit ≥5 units following treatment occurred in 57 children [23 %] between 14 and 28 days after treatment began. Baseline parasitaemia and proportion with > 100,000μL^-1 asexual forms were significantly higher in children with ≥5 units compared to <5 units fall in haematocrit 21 or 28 days after treatment began. Irrespective of pattern, declines in haematocrit deficit from <30 % were mono-exponential, with similar half-times for AA- and AL-treated children (1.32 d versus 1.14 d). Anaemia half-time correlated significantly positively with anaemia recovery time in the same patients (r = 0.55, P < 0.0001). Bland-Altman analysis of 9 or 10 multiples of anaemia half-time and anaemia recovery times showed narrow limit of agreement with insignificant biases (P = 0.19 or 0.63, respectively).

Conclusions

In uncomplicated falciparum malaria, increases or falls in haematocrit are common following ACTs. Falls in haematocrit ≥ 5 units are common and may or may not result in early or late anaemia. In children who recovered from acute falciparum malaria-associated anaemia following ACTs, decline in haematocrit deficit is mono-exponential.

Trials registration

Pan African Clinical Trial Registry PACTR201508001188143, 3 July 2015; PACTR201508001191898, 7 July 2015 http://www.pactr.org.

Electronic supplementary material

The online version of this article (doi:10.1186/s12879-015-1219-y) contains supplementary material, which is available to authorized users.

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.