Sustained clinical efficacy of sulfadoxine-pyrimethamine for uncomplicated falciparum malaria in Malawi after 10 years as first line treatment: five year prospective study

Objective To measure the efficacy of sulfadoxine-pyrimethamine treatment of falciparum malaria in Malawi from 1998 to 2002, after a change from chloroquine to sulfadoxine-pyrimethamine as first line treatment in that country in 1993.Design Prospective open label drug efficacy study.Setting Health centre in large peri-urban township adjacent to Blantyre, Malawi.Participants People presenting to a health centre with uncomplicated Plasmodium falciparum malaria.Main outcome measures Therapeutic efficacy and parasitological resistance to standard sulfadoxine-pyrimethamine treatment at 14 days and 28 days of follow up.Results Therapeutic efficacy remained stable, with adequate clinical response rates of 80% or higher throughout the five years of the study. Analysis of follow up to 28 days showed modest but significant trends towards diminishing clinical and parasitological efficacy over time within the study period.Conclusion Contrary to expectations, sulfadoxine-pyrimethamine has retained good efficacy after 10 years as the first line antimalarial drug in Malawi. African countries with very low chloroquine efficacy, high sulfadoxine-pyrimethamine efficacy, and no other immediately available alternatives may benefit from interim use of sulfadoxine-pyrimethamine while awaiting implementation of combination antimalarial treatments.     

Efficacy of artesunate-amodiaquine for the treatment of acute uncomplicated falciparum malaria in southern Mauritania

Mathematical analyses and modelling have an important role informing malaria eradication strategies. Simple mathematical approaches can answer many questions, but it is important to investigate their assumptions and to test whether simple assumptions affect the results. In this note, four examples demonstrate both the effects of model structures and assumptions and also the benefits of using a diversity of model approaches. These examples include the time to eradication, the impact of vaccine efficacy and coverage, drug programs and the effects of duration of infections and delays to treatment, and the influence of seasonality and migration coupling on disease fadeout. An excessively simple structure can miss key results, but simple mathematical approaches can still achieve key results for eradication strategy and define areas for investigation by more complex models.     

Efficacy of two artemisinin combination therapies for uncomplicated falciparum malaria in children under 5 years, Malakal, Upper Nile, Sudan

Background

The treatment for Plasmodium falciparum malaria in Sudan has been in process of change since 2003. Preceding the change, this study aimed to determine which artemisinin-based combination therapies is more effective to treat uncomplicated malaria in Malakal, Upper Nile, Sudan.

Methods

Clinical trial to assess the efficacy of 2 antimalarial therapies to treat P. falciparum infections in children aged 6–59 months, in a period of 42 days after treatment.

Results

A total of 269 children were followed up to 42 days. Artesunate plus Sulfadoxine/Pyrimethamine (AS+SP) and Artesunate plus Amodiaquine (AS+AQ) were both found to be efficacious in curing malaria infections by rapid elimination of parasites and clearance of fever, in preventing recrudescence and suppressing gametocytaemia. The combination of AS+SP appeared slightly more efficacious than AS+AQ, with 4.4% (4/116) versus 15% (17/113) of patients returning with malaria during the 6-week period after treatment (RR = 0.9, 95% CI 0.81–0.96). PCR analysis identified only one recrudescence which, together with one other early treatment failure, gave efficacy rates of 99.0% for AS+AQ (96/97) and 99.1% for AS+SP (112/113). However, PCR results were incomplete and assuming part of the indeterminate samples were recrudescent infections leads to an estimated efficacy ranging 97–98% for AS+SP and 88–95% for AS+AQ.

Conclusion

These results lead to the recommendation of ACT, and specifically AS+SP, for the treatment of uncomplicated falciparum malaria in this area of Sudan. When implemented, ACT efficacy should be monitored in sentinel sites representing different areas of the country.     

Plasmodium falciparum: evaluation of a quantitative nucleic acid sequence-based amplification assay to predict the outcome of sulfadoxine-pyrimethamine treatment of uncomplicated malaria

A quantitative nucleic acid sequence-based amplification (QT-NASBA) assay was employed to predict retrospectively the outcome of sulfadoxine-pyrimethamine (SP) treatment of uncomplicated malaria in children aged <6 years in an endemic region. Blood samples were collected at initial diagnosis and during follow-up. Mutation-specific nested PCR methods to analyse DHFR (Arg-59) and DHPS (Glu-540) mutations that are associated with SP drug resistance were applied. Parasite genotyping was performed to distinguish between re-infection and recrudescence. Eighty-six patients were recruited of which 66 were available for follow-up. Nine children were classified as early treatment failure, 13 cases were classified as late clinical failure, 32 as late parasitological failure, and only 12 children had an adequate clinical and parasitological response. DHFR and DHPS mutations conferring SP resistance were abundant in the Plasmodium population. Blood samples obtained 7 days after treatment were used to predict retrospectively the outcome of SP treatment. QT-NASBA was able to give a correct prediction of treatment outcome in 85.7% of the cases. Positive predictive value (PPV) of QT-NASBA case was 95% (95% confidence interval = 88.3-100) and negative predictive value (NPV) was 63% (95% CI = 39.5-86.5). In contrast, microscopy correctly predicted outcome in only 37.5% of the cases. PPV of microscopy was 100% (95% CI = 73.9-100) and the NPV was 25.5% (95% CI = 13.0-38.0). The analysis of a day 7 blood sample with QT-NASBA allows for the prediction of late clinical or parasitological treatment failure in the majority of the cases analysed in the present study.     

Gametocyte clearance in uncomplicated and severe Plasmodium falciparum malaria after artesunate-mefloquine treatment in Thailand

Artemisinin-based combination therapy (ACT) is currently promoted as a strategy for treating both uncomplicated and severe falciparum malaria, targeting asexual blood-stage Plasmodium falciparum parasites. However, the effect of ACT on sexual-stage parasites remains controversial. To determine the clearance of sexual-stage P. falciparum parasites from 342 uncomplicated, and 217 severe, adult malaria cases, we reviewed and followed peripheral blood sexual-stage parasites for 4 wk after starting ACT. All patients presented with both asexual and sexual stage parasites on admission, and were treated with artesunate-mefloquine as the standard regimen. The results showed that all patients were asymptomatic and negative for asexual forms before discharge from hospital. The percentages of uncomplicated malaria patients positive for gametocytes on days 3, 7, 14, 21, and 28 were 41.5, 13.1, 3.8, 2.0, and 2.0%, while the percentages of gametocyte positive severe malaria patients on days 3, 7, 14, 21, and 28 were 33.6, 8.2, 2.7, 0.9, and 0.9%, respectively. Although all patients were negative for asexual parasites by day 7 after completion of the artesunate-mefloquine course, gametocytemia persisted in some patients. Thus, a gametocytocidal drug, e.g., primaquine, may be useful in combination with an artesunate-mefloquine regimen to clear gametocytes, so blocking transmission more effectively than artesunate alone, in malaria transmission areas.     

A randomized controlled pilot trial of azithromycin or artesunate added to sulfadoxine-pyrimethamine as treatment for malaria in pregnant women

Objective

New anti-malarial regimens are urgently needed in sub-Saharan Africa because of the increase in drug resistance. We investigated the safety and efficacy of azithromycin or artesunate combined with sulfadoxine-pyrimethamine used for treatment of malaria in pregnant women in Blantyre, Malawi.

Methods/Findings

This was a randomized open-label clinical trial, conducted at two rural health centers in Blantyre district, Malawi. A total of 141 pregnant women with uncomplicated Plasmodium falciparum malaria were recruited and randomly allocated to 3 treatment groups: sulfadoxine-pyrimethamine (SP; 3 tablets, 500 mg sulfadoxine and 25 mg pyrimethamine per tablet); SP plus azithromycin (1 g/day×2 days); or SP plus artesunate (200 mg/day×3 days). Women received two doses administered at least 4 weeks apart. Heteroduplex tracking assays were performed to distinguish recrudescence from new infections. Main outcome measures were incidence of adverse outcomes, parasite and fever clearance times and recrudescence rates. All treatment regimens were well tolerated. Two women vomited soon after ingesting azithromycin. The parasite clearance time was significantly faster in the SP-artesunate group. Recrudescent episodes of malaria were less frequent with SP-azithromycin [Hazard Ratio 0.19 (95% confidence interval 0.06 to 0.63)] and SP-artesunate [Hazard Ratio 0.25 (95% confidence interval 0.10 to 0.65)] compared with SP monotherapy. With one exception (an abortion in the SP-azithromycin group), all adverse pregnancy outcomes could be attributed to known infectious or obstetrical causes. Because of the small sample size, the effect on birth outcomes, maternal malaria or maternal anemia could not be evaluated.

Conclusions

Both SP-artesunate and SP-azithromycin appeared to be safe, well tolerated and efficacious for the treatment of malaria during pregnancy. A larger study is needed to determine their safety and efficacy in preventing poor birth outcomes.

Trial Registration

ClinialTrials.gov {"type":"clinical-trial","attrs":{"text":"NCT00287300","term_id":"NCT00287300"}}NCT00287300     

Efficacy of chloroquine plus primaquine treatment and pfcrt mutation in uncomplicated falciparum malaria patients in Rangamati, Bangladesh

A combination of chloroquine (CQ) and primaquine (PQ) had been used as the first-line treatment of uncomplicated Plasmodium falciparum malaria in Rangamati, Bangladesh until the end of 2004. Doctors or medical staffs had felt that CQ plus PQ had become less effective against uncomplicated falciparum malaria patients, but that it was more effective against the minority-indigenous patients than the Bengali patients. The efficacy of CQ plus PQ and the mutation status of the CQ resistance transporter (pfcrt) gene of infecting P. falciparum were, thus, investigated for 45 uncomplicated falciparum malaria patients in Rangamati in 2004. The total failure rate was 57.8%. One or two pfcrt sequences (CIETH and SMNTH at positions 72, 74-76, and 97, mutation underlined) with K76T mutation known to be related to CQ-resistant phenotype were detected in 38 patients' blood samples. Of the 38 patients, in total 15 patients (14/25 minority-indigenous and 1/13 Bengali patients) resulted in adequate clinical and parasitological response (ACPR). There was a statistically significant difference in ACPR rate between the minority-indigenous patients and the Bengali patients. P. falciparum with mutant or resistant pfcrt (pfcrt-resistant) was detected by PCR in blood samples on day 28 for 10 ACPR minority-indigenous patients but not for the only one Bengali ACPR patient, who all were infected with pfcrt-resistant P. falciparum on day 0. The minority-indigenous patients, but not Bengalis, are suggested to be often cured by CQ plus PQ, leaving a very few parasites detectable only by PCR, even when they are infected with pfcrt-resistant P. falciparum.     

Efficacy of artemether-lumefantrine, the nationally-recommended artemisinin combination for the treatment of uncomplicated falciparum malaria, in southern Laos

ABSTRACT: BACKGROUND: The Lao Government changed the national policy for uncomplicated Plasmodium falciparum malaria from chloroquine to artemether-lumefantrine (AL) in 2005. Since then, no information on AL efficacy has been reported. With evidence of resistance to artemisinin derivatives in adjacent Cambodia, there has been a concern as to AL efficacy. Monitoring of AL efficacy would help the Lao Government to make decisions on appropriate malaria treatment. METHODS: The efficacy of a three-day, twice daily oral artemether-lumefantrine for the treatment of uncomplicated falciparum malaria in Xepon District, Savannakhet Province, southern Laos was studied over 42 days follow-up. This was part of a trial of thiamin supplementation in falciparum malaria. RESULTS: Of 630 patients with P. falciparum enrolled in the trial of thiamin treatment, 549 (87%, 357 children [less than or equal to]15 years and 192 adults) were included in this study. The per protocol 42-day cure rates were 97% (524/541) [96% (337/352) for children and 99% (187/189) for adults, p = 0.042]. By conventional intention-to-treat analysis, the 42-day cure rates adjusted for re-infection, were 97% (532/549) [96% (342/357) in children and 99% (190/192) in adults, p = 0.042]. The proportion of patients who remained parasitaemic at day 1 after treatment was significantly higher in children [33% (116/356)] compared to adults [15% (28/192)] (p < 0.001) and only one adult patient had detectable parasitaemia on day 2. There were no serious adverse events. Potential side effects after treatment were reported more commonly in adults (32%) compared to children (15%) (p < 0.001). Patients with recrudescent infections were significantly younger, had longer mean time to fever clearance, and had longer median time to parasite clearance compared to those who were cured. CONCLUSIONS: The current nationally-recommended anti-malarial treatment (artemether-lumefantrine) remains highly efficacious for the treatment of uncomplicated falciparum malaria five years after introduction in Laos. Regular monitoring is required in case artemisinin-resistant P. falciparum parasites should appear. Trial registration ISRCTN85411059.     

A cost-effectiveness analysis of provider and community interventions to improve the treatment of uncomplicated malaria in Nigeria: study protocol for a randomized controlled trial

ABSTRACT: BACKGROUND: There is mounting evidence of poor adherence by health service personnel to clinical guidelines for malaria following a symptomatic diagnosis. In response to this, the World Health Organization (WHO) recommends that in all settings clinical suspicion of malaria should be confirmed by parasitological diagnosis using microscopy or Rapid Diagnostic Test (RDT). The Government of Nigeria plans to introduce RDTs in public health facilities over the coming year. In this context, we will evaluate the effectiveness and cost-effectiveness of two interventions designed to support the roll-out of RDTs and improve the rational use of ACTs. It is feared that without supporting interventions, non-adherence will remain a serious impediment to implementing malaria treatment guidelines. Methods/design A three-arm stratified cluster randomized trial is used to compare the effectiveness and costeffectiveness of: (1) provider malaria training intervention versus expected standard practice in malaria diagnosis and treatment; (2) provider malaria training intervention plus schoolbased intervention versus expected standard practice; and (3) the combined provider plus school-based intervention versus provider intervention alone. RDTs will be introduced in all arms of the trial. The primary outcome is the proportion of patients attending facilities that report a fever or suspected malaria and receive treatment according to malaria guidelines. This will be measured by surveying patients (or caregivers) as they exit primary health centers, pharmacies, and patent medicine dealers. Cost-effectiveness will be presented in terms of the primary outcome and a range of secondary outcomes, including changes in provider and community knowledge. Costs will be estimated from both a societal and provider perspective using standard economic evaluation methodologies. Trial registration Clinicaltrials.gov NCT01350752.     

Regioselectively modified sulfated cellulose as prospective drug for treatment of malaria tropica

Adhesion of Plasmodium falciparum infected erythrocytes (IE) to placental chondroitin-4-sulfate (CSA) has been linked to the severe disease outcome of pregnancy-associated malaria. Consequently, sulfated polysaccharides with inhibitory capacity may be considered for therapeutic strategies as anti-adhesive drugs. During in vitro screening a regioselectively modified cellulose sulfate (CS10) was selected as prime candidate for further investigations because it was able to inhibit adhesion to CSA expressed on CHO cells and placental tissue, to de-adhere already bound infected erythrocytes, and to bind to infected erythrocytes. Similar to the undersulfated placental CSA preferred by placental-binding infected erythrocytes, CS10 is characterized by a clustered sulfate pattern along the polymer chain. In further evaluation of its effects on P. falciparum interactions with host erythrocytes, we now show that CS10 inhibits the in vitro asexual growth of parasites in erythrocytes. Furthermore, we show that CS10 interferes with C1 of the classical complement pathway but not with MBL of the lectin pathway. In order to gain insights into the possible interactions of CS10 with known parasite receptors at the molecular level, we designed 3D-structures of characteristic stretches of CS10. CS10 fragments with clustered sulfate groups showed complex patterns of hydrophobic and hydrophilic patches most likely suitable for interactions with protein binding partners. The significance of CS10 interactions with the complement system as well as its anti-malarial effect for prospective drug application are discussed.     

Methodology of assessment and reporting of safety in anti-malarial treatment efficacy studies of uncomplicated falciparum malaria in pregnancy: a systematic literature review

Background

Considering the uncertainty of safety of anti-malarial drugs in pregnancy, efficacy studies are one of the few sources of clinical safety data. Complete safety evaluation is not usually incorporated in efficacy studies due to financial and human resource constraints. This review reports the methods used for the assessment of safety of artemisinin-based and quinine-based treatments in efficacy studies in pregnancy.

Methods

Methodology of assessment and reporting of safety in efficacy studies of artemisinin-based and quinine-based treatment in pregnancy was reviewed using seven databases and two clinical trial registries. The protocol was registered to PROSPERO (CRD42017054808).

Results

Of 48 eligible efficacy studies the method of estimation of gestational age was reported in only 32 studies (67%, 32/48) and ultrasound was used in 18 studies (38%, 18/48). Seventeen studies (35%, 17/48) reported parity, 9 (19%, 9/48) reported gravidity and 13 (27%, 13/48) reported both. Thirty-eight studies (79%, 38/48) followed participants through to pregnancy outcome. Fetal loss was assessed in 34 studies (89%, 34/38), but the definition of miscarriage and stillbirth were defined only in 11 (32%, 11/34) and 7 (21%, 7/34) studies, respectively. Preterm birth was assessed in 26 studies (68%, 26/38) but was defined in 16 studies (62%, 16/26). Newborn weight was assessed in 30 studies (79%, 30/38) and length in 10 studies (26%, 10/38). Assessment of birth weight took gestational age into account in four studies (13%, 4/30). Congenital abnormalities were reported in 32 studies (84%, 32/38). Other common risk factors for adverse pregnancy outcomes were not well-reported.

Conclusion

Incomplete reporting and varied methodological assessment of pregnancy outcomes in anti-malarial drug efficacy studies limits comparison across studies. A standard list of minimal necessary parameters to assess and report the safety component of efficacy studies of anti-malarials in pregnancy is proposed.

     

Efficacy of artemether-lumefantrine treatment in patients with acute uncomplicated Falciparum malaria in Mayotte, a French collectivity of the Comoros Archipelago

Mayotte is a French island located in the Comoros archipelago in the Indian Ocean. Due to the high level of resistance to chloroquine and sulfadoxine-pyrimethamine in this area, new therapeutic strategies are required. The aim was to assess and to document the efficacy of artemether-lumefantrine (AL) combination in four oral dosages. The follow-up was carried out during 21 days to monitor the antimalarial drug efficacy in an open trial in April-May, 2002. Results were obtained from 51 patients, aged from three to 46 years (12% less than five years). No case of therapeutic failure was observed. At day 2 after treatment, all the patients were apyretic and none of them had parasitaemia until day 21. This first therapeutic trial of the AL combination in the Indian Ocean sub-region shows that this association is safe, effective and rapid. AL should be an alternative treatment of uncomplicated malaria attacks in Comoros Archipelago, and will be of help to manage imported chloroquine-resistant falciparum malaria strains in Madagascar.     

Step towards elimination of Wuchereria bancrofti in Southwest Tanzania 10 years after mass drug administration with Albendazole and Ivermectin

BackgroundLymphatic filariasis is a mosquito transmitted parasitic infection in tropical regions. Annual mass treatment with ivermectin and albendazole is used for transmission control of Wuchereria bancrofti, the infective agent of lymphatic filariasis in many African countries, including Tanzania.MethodologyIn a general population study in Southwest Tanzania, individuals were tested for circulating filarial antigen, an indicator of W. bancrofti adult worm burden in 2009 before mass drug administration commenced in that area. Seven annual rounds with ivermectin and albendazole were given between 2009 and 2015 with a population coverage of over 70%. Participants of the previous study took part in a follow-up activity in 2019 to measure the effect of this governmental activity.FindingsOne thousand two hundred and ninety nine inhabitants of Kyela district in Southwest Tanzania aged 14 to 65 years who had participated in the study activities in 2009 were revisited in 2010/11 and 2019. Among this group, the prevalence of lymphatic filariasis of the 14–65 years olds in 2009 was 35.1%. A follow-up evaluation in 2010/11 had shown a reduction to 27.7%. In 2019, after 7 years of annual treatment and an additional three years of surveillance, the prevalence had dropped to 1.7%, demonstrating successful treatment by the national control programme. Risk factors for W. bancrofti-infection were the occupation as farmer, male sex, and older age. Most infected individuals in the 2019 follow-up study already had a positive test for filarial antigen in 2009 and/or 2010/11.ConclusionsThis data supports the findings of the Tanzanian Neglected Tropical Disease Control Programme (NTDCP), who conducted Transmission Assessment Surveys and found an impressive reduction in the prevalence of LF in children. Our results complement this data by showing a similar decrease in prevalence of LF in the adult population in the same area. The elimination of LF seems achievable in the near future.     

Genetic and structural characterization of PvSERA4: potential implication as therapeutic target for Plasmodium vivax malaria

Plasmodium vivax malaria is geographically the most widely distributed and prevalent form of human malaria. The development of drug resistance by the parasite to existing drugs necessitates higher focus to explore and identify new drug targets. Plasmodial proteases have key roles in parasite biology and are involved in nutritional uptake, egress from infected reticulocytes, and invasion of the new target erythrocytes. Serine repeat antigens (SERA) of Plasmodium are parasite proteases that remain attractive drug targets and are important vaccine candidates due to their high expression profiles in the blood stages. SERA proteins have a unique putative papain-like cysteine protease motif that has either serine or cysteine in its active site. In P. vivax, PvSERA4 is the highest transcribed member of this multigene family. In this study, we have investigated the genetic polymorphism of PvSERA4 central protease domain and deduced its 3D model by homology modeling and also performed MD simulations to acquire refined protein structure. Sequence analysis of protease domain of PvSERA4 from Indian field isolates reveals that the central domain is highly conserved. The high sequence conservation of the PvSERA4 enzyme domain coupled with its high expression raises the possibility of it having a critical role in parasite biology and hence, being a reliable target for new selective inhibitor-based antimalarial chemotherapeutics. The 3D model showed the presence of an unusual antiparallel Beta hairpin motif between catalytic residues similar to hemoglobin binding motif of Plasmodial hemoglobinases. Our PvSERA4 model will aid in designing structure-based inhibitors against this enzyme.