Efficacy of Olyset Duo, a bednet containing pyriproxyfen and permethrin, versus a permethrin-only net against clinical malaria in an area with highly pyrethroid-resistant vectors in rural Burkina Faso: a cluster-randomised controlled trial.

BACKGROUND: Substantial reductions in malaria incidence in sub-Saharan Africa have been achieved with massive deployment of long-lasting insecticidal nets (LLINs), but pyrethroid resistance threatens control. Burkina Faso is an area with intense malaria transmission and highly pyrethroid-resistant vectors. We assessed the effectiveness of bednets containing permethrin, a pyrethroid, and pyriproxyfen, an insect growth regulator, versus permethrin-only (standard) LLINs against clinical malaria in children younger than 5 years in Banfora, Burkina Faso. METHODS: In this two-group, step-wedge, cluster-randomised, controlled, superiority trial, standard LLINs were incrementally replaced with LLINs treated with permethrin plus pyriproxyfen (PPF) in 40 rural clusters in Burkina Faso. In each cluster, 50 children (aged 6 months to 5 years) were followed up by passive case detection for clinical malaria. Cross-sectional surveys were done at the start and the end of the transmission seasons in 2014 and 2015. We did monthly collections from indoor light traps to estimate vector densities. Primary endpoints were the incidence of clinical malaria, measured by passive case detection, and the entomological inoculation rate. Analyses were adjusted for clustering and for month and health centre. This trial is registered as ISRCTN21853394. FINDINGS: 1980 children were enrolled in the cohort in 2014 and 2157 in 2015. At the end of the study, more than 99% of children slept under a bednet. The incidence of clinical malaria was 2·0 episodes per child-year in the standard LLIN group and 1·5 episodes per child-year in the PPF-treated LLIN group (incidence rate ratio 0·88 [95% CI 0·77-0·99; p=0·04]). The entomological inoculation rate was 85 (95% CI 63-108) infective bites per transmission season in the standard LLIN group versus 42 (32-52) infective bites per transmission season in the PPF-treated LLIN group (rate ratio 0·49, 95% CI 0·32-0·66; p<0·0001). INTERPRETATION: PPF-treated LLINs provide greater protection against clinical malaria than do standard LLINs and could be used as an alternative to standard LLINs in areas with intense transmission of Plasmodium falciparum malaria and highly pyrethroid-resistant vectors. FUNDING: EU Seventh Framework Programme.

In vitro antiplasmodial activity of some medicinal plants of Burkina Faso.

Malaria remains a major public health problem due to the emergence and spread of Plasmodium falciparum drug resistance. There is an urgent need to investigate new sources of antimalarial drugs which are more effective against Plasmodium falciparum. One of the potential sources of antimalarial drugs is traditional medicinal plants. In this work, we studied the in vitro antiplasmodial activity of chloromethylenic, methanolic, and MeOH/H2O (1/1) crude extracts and decoction obtained from eight medicinal plants collected in Burkina Faso and of total alkaloids for five plants. Extracts were evaluated in vitro for efficacy against Plasmodium falciparum strain K1, which is resistant to chloroquine, pyrimethamine and proguanil using the fluorescence-based SYBR Green I assay. The antiproliferative activity on human-derived hepatoma cell line HepG2 and Chinese hamster ovary (CHO) cells was evaluated using the 3-[4,5-dimethylthyazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) test in order to determine the selectivity index. Among the plant extracts tested for in vitro antiplasmodial activity, 16 were considered to be inactive (with IC50 > 10 µg/ml), six showed a moderate activity (5 < IC50 ≤ 10 µg/ml), and six were found to have a good in vitro activity with IC50 value ≤ 5 µg/ml. The highest antiplasmodial activity was found for extracts from: the alkaloid leaf extract and the chloromethylenic extracts of Combretum fragrans (IC50 = 3 µg/ml, IC50 = 5 µg/ml), the total alkaloids and the chloromethylenic leaf extracts of Combretum collinum (IC50 = 4 µg/ml), the MeOH/H2O leaf extract of Terminalia avicennioides (IC50 = 3.5 µg/ml), and the alkaloid leaf extract of Pavetta crassipes (IC50 = 5 µg/ml). Three other extracts showed moderate antiplasmodial activity (5 < IC50 ≤ 10 µg/ml): Terminalia avicennioides and Combretum fragrans methanolic extracts and Acacia kirkii alkaloid leaf extract (IC50 = 6.5, 9 and 10 µg/ml respectively). The Terminalia avicennioides crude MeOH/H2O (80:20 v/v) extract of the leaves was submitted to a successive liquid/liquid extraction with ethylacetate and n-butanol respectively. The extracts were investigated for in vitro antiplasmodial activity and antioxidant properties using DPPH(·), ABTS(+) and FRAP methods. The ethylacetate extract showed the best antiplasmodial activity (7 µg/ml) and the active constituent was isolated as ellagic acid by bioguided fractionation with an IC50 = 0.2 µM on Plasmodium falciparum and SI = 152. Besides, Terminalia avicennioides leaf extract and ellagic acid showed a good antioxidant activity. Our finding confirms the importance of investigating the antimalarial activity of plant species used in traditional medicine. Overall, two plants belonging to the Combretaceae family, Combretum fragrans and Combretum collinum appeared to be the best candidates and will be further investigated for their antiplasmodial properties, in order to isolate the molecules responsible for the antiplasmodial activity.

Haemoglobin variants and Plasmodium falciparum malaria in children under five years of age living in a high and seasonal malaria transmission area of Burkina Faso.

BACKGROUND: Genetic factors play a key role in determining resistance/susceptibility to infectious disease. Susceptibility of the human host to malaria infection has been reported to be influenced by genetic factors, which could be confounders if not taken into account in the assessment of the efficacy of interventions against malaria. This study aimed to assess the relationship between haemoglobin genotypes and malaria in children under five years in a site being characterized for future malaria vaccine trials. METHODS: The study population consisted of 452 children living in four rural villages. Hb genotype was determined at enrolment. Clinical malaria incidence was evaluated over a one-year period using combined active and passive surveillance. Prevalence of infection was evaluated via bi-annual cross-sectional surveys. At each follow-up visit, children received a brief clinical examination and thick and thin blood films were prepared for malaria diagnosis. A clinical malaria was defined as Plasmodium falciparum parasitaemia >2,500 parasites/µl and axillary temperature ≥37.5°C or reported fever over the previous 24 hours. RESULTS: Frequencies of Hb genotypes were 73.2% AA; 15.0% AC; 8.2% AS; 2.2% CC; 1.1% CS and 0.2% SS. Prevalence of infection at enrolment ranged from 61.9%-54.1% among AA, AC and AS children. After one year follow-up, clinical malaria incidence (95% CI) (episodes per person-year) was 1.9 (1.7-2.0) in AA, 1.6 (1.4-2.1) in AC, and 1.7 (1.4-2.0) in AS children. AC genotype was associated with lower incidence of clinical malaria relative to AA genotype among children aged 1-2 years [rate ratio (95% CI) 0.66 (0.42-1.05)] and 2-3 years [rate ratio (95% CI) 0.37 (0.18-0.75)]; an association of opposite direction was however apparent among children aged 3-4 years. AS genotype was associated with lower incidence of clinical malaria relative to AA genotype among children aged 2-3 years [rate ratio (95% CI) 0.63 (0.40-1.01)]. CONCLUSIONS: In this cohort of children, AC or AS genotype was associated with lower risk of clinical malaria relative to AA genotype only among children aged one to three years. It would be advisable for clinical studies of malaria in endemic regions to consider haemoglobin gene differences as a potentially important confounder, particularly among younger children.

Microbiological quality assessment of five common foods sold at different points of sale in Burkina-Faso.

The aim of the present study was to assess the microbial quality of five ready-to-eat food such as bread, pasta, rice with sauce, beans and milk sold in five localities of Burkina Faso namely, Ouagadougou, Bobo-Dioulasso, Dakola, Cinkansé and Niangoloko. One hundred and one samples were collected and microbial quality were assessed by evaluating the food hygiene indicators such as total aerobic mesophilic flora, total coliforms, thermotolerant coliforms, yeast and mould. Food safety indicators such as Escherichia coli, Salmonella, coagulase-positive staphylococci, Clostridium perfringens and Bacillus cereus were also tested for contamination. Samples were tested according to ISO guidelines for all parameters. The results showed that 74 (73.27%) of samples were satisfactory while 15 (14.85%) were acceptable and 12 (11.88%) were not satisfactory according to international standards. Among the food safety indicators sought, Escherichia coli was detected in two samples and Bacillus cereus in four samples. Most of the analyzed food exhibited good hygiene behavior within the acceptable limits and the highest of not satisfactory rate was observed in milk powder and rice with sauce. Ouagadougou samples recorded the highest number of not satisfactory samples. Despite the general quality was satisfactory, the presence of specific microorganisms such as coliforms is indicative of the poor hygiene surrounded these foods. It is therefore necessary to train and follow up the vendors in the handling of equipment, hand-washing practices and selling environment hygiene for better improvement of the quality of the street foods.

Nutritional, Microbiological, and Toxicological Quality Assessment of Foods Sold in Urban and Suburban Markets in Burkina Faso.

Food safety risks are becoming a public health problem with important socioeconomic consequences for human wellbeing, especially for pregnant women and infants. In this article, we describe findings from microbiological, toxicological, and nutritional quality assessments of foods from 5 localities in Burkina Faso, with the aim to provide baseline data on the quality of food and the risks to mothers and children. Samples for assessment included food sold in markets, stores, and restaurants (eg, cereals, oilseeds, vegetables, edible oils, powdered milk, dried fish, packaged water, ready-to-eat meals). The research team selected the samples using the random route method and analyzed them at the National Public Health Laboratory in Ouagadougou between January and December 2020. A total of 443 food samples were collected, of which 101 were analyzed for microbial contamination, 360 were analyzed for the presence of toxins, and 59 were analyzed for their nutritional value. The microbiological quality of 11.88% of the food samples was unsatisfactory, and 41.50% were contaminated with aflatoxins. At least 1 pesticide residue and cyfluthrin were detected in 58.10% of samples. The most detected contaminant (cyfluthrin) was found in 79.10% of the analyzed samples. A peroxide index higher than the normal value (10 mEq/kg) was found in 3.38% of the oil samples and 76.27% of the oil samples had a vitamin A content lower than the recommended limit of 11 mg/kg. This study is the first in Burkina Faso that provides baseline data on the quality of food and potential health risks to mothers and children in Burkina Faso. Considering the level of contaminants reported in this article, it is imperative to enhance routine monitoring of foods in the country.

Antiplasmodial activity and toxicity of crude extracts from alternatives parts of plants widely used for the treatment of malaria in Burkina Faso: contribution for their preservation.

In order to prevent the destruction of the ecology and to sustain the flora mainly for medicinal plants, we investigated on alternative parts taken from four plants already known to display antiplasmodial activities and largely used by traditional healers in sub-Saharan Africa. The evaluated parts are bark of trunk for Zanthoxylum zanthoxyloides and leaves for Sarcocephalus latifolius instead of roots, and leaves for Combretum molle and Anogeissus leiocarpus instead of stem bark. The antiplasmodial activity of extracts of these plants was evaluated in vitro using the multi-resistant strain (W2) of Plasmodium falciparum. Antiproliferative activity was also assessed, using K562S human monocyte cell lines, along with calculation of the selectivity index (SI) of each extract. The highest in vitro antiplasmodial activity was found in the alkaloid extract of trunk bark from Z. zanthoxyloides and from the MeOH extract of A. leiocarpus leaves (IC(50) = 1.2 microg/mL and 4.9 microg/mL, respectively) with good selectivity index. Moderate activity was found in the MeOH extract (IC(50) = 5.7 microg/mL) and MeOH/H2O extract (IC(50) = 7.9 microg/mL) of C. molle leaves. Moderate activity was also found in the MeOH/H20 extract (IC(50) = 5.2 microg/mL) and the decoction (IC(50) = 8.2 microg/mL) from leaves of A. leiocarpus. No good activity was found with extracts from roots of S. latifolius. All extracts tested displayed low levels of cytotoxicity against K562S cells. The data generated clearly show that the trunk bark for Z. zanthoxyloides and the leaves for A. leiocarpus and C. molle could be used for the treatment of malaria instead of roots and stem bark.

Phytochemical and pharmacological study of roots and leaves of Guiera senegalensis J.F. Gmel (Combretaceae).

The chemical composition of total alkaloids from leaves and roots of Guiera senegalensis was investigated. Three beta-carboline alkaloids were purified: in addition to harman and tetrahydroharman, known in roots and leaves, harmalan (dihydroharman) was isolated for the first time from roots of Guiera senegalensis. Guieranone A, a naphthyl butenone, was also purified from leaves and roots. The in vitro antiplasmodial activity and the cytotoxicity of extracts and pure compounds were evaluated. Each total alkaloid extract and beta-carboline alkaloids presented an interesting antiplasmodial activity associated with a low cytotoxicity. Harmalan was less active than harman and tetrahydroharman. Guieranone A showed a strong antiplasmodial activity associated with a high cytotoxicity toward human monocytes. Its cytotoxicity was performed against two cancer cell lines and normal skin fibroblasts in order to study its anticancer potential: guieranone A presented a strong cytotoxicity against each cell strains. Finally, we evaluated the potent synergistic antimalarial interaction between Guiera senegalensis and two plants commonly associated in traditional remedies: Mitragyna inermis and Pavetta crassipes. Three associations evaluated were additive. A synergistic effect was shown between total alkaloids extracted from leaves of Guiera senegalensis and those of Mitragyna inermis. This result justified the traditional use of the plants in combination to treat malaria.

Antimalarial activity of Sida acuta Burm. f. (Malvaceae) and Pterocarpus erinaceus Poir. (Fabaceae).

Among strategies to combat malaria, the search for new antimalarial drugs appears to be a priority. Sheering for new antimalarial activities, four plants of the traditional medicine of Burkina Faso: Combretum micranthum, Khaya senegalensis, Pterocarpus erinaceus and Sida acuta, were tested in vitro on fresh clinical isolates of Plasmodium falciparum. The screening showed that Sida acuta has a significant activity (IC50 < 5 microg/ml), and Pterocarpus erinaceus has a moderate activity (5 microg/ml < IC50 < 50 microg/ml). Further chemical screening showed that the activity of the most active plant, Sida acuta, was related to its alkaloid contents.

Assessment of chimpanzee adenovirus serotype 63 neutralizing antibodies prior to evaluation of a candidate malaria vaccine regimen based on viral vectors.

Prior to a chimpanzee adenovirus-based (ChAd63) malarial vaccine trial, sera were collected to assess ChAd63-specific neutralizing antibody titers in Banfora (Burkina Faso). The low neutralizing antibody titers reported in both adults and children (median titers, 139.1 and 35.0, respectively) are encouraging for the potential use of ChAd63 as a malarial vaccine vector.

In vitro antiplasmodial and cytotoxic properties of some medicinal plants from western Burkina Faso.

BACKGROUND: Resistance of malaria parasites to existing drugs complicates treatment, but an antimalarial vaccine that could protect against this disease is not yet available. It is therefore necessary to find new effective and affordable medicines. Medicinal plants could be a potential source of antimalarial agents. Some medicinal plants from Burkina Faso were evaluated for their antiplasmodial and cytotoxic properties in vitro. METHODS: Crude dichloromethane, methanol, water-methanol, aqueous and alkaloids extracts were prepared for 12 parts of 10 plants. Chloroquine-resistant malaria strain K1 was used for the in vitro sensibility assay. The Plasmodium lactacte dehydrogenase technique was used to determine the 50% inhibitory concentration of parasites activity (IC50). The cytotoxic effects were determined with HepG2 cells, using the tetrazolium-based colorimetric technique, and the selectivity index (SI) was calculated. RESULTS: Sixty crude extracts were prepared. Seven extracts from Terminalia avicenoides showed IC50 < 5 µg/mL. The IC50 of dichloromethane, methanol, aqueous and alkaloids extracts ranged between 1.6 µg/mL and 4.5 µg/mL. Three crude extracts from Combretum collinum and three from Ficus capraefolia had an IC50 ranging between 0.2 µg/mL and 2.5 µg/mL. Crude extracts from these three plants had no cytotoxic effect, with SI > 1. The other plants have mostly moderate or no antimalarial effects. Some extracts from Cordia myxa, Ficus capraefolia and Opilia celtidifolia showed cytotoxicity, with an SI ranging between 0.4 and 0.9. CONCLUSION: Our study showed a good antiplasmodial in vitro activity of Terminalia avicenoides, Combretum collinum and Ficus capraefolia. These three plants may contain antiplasmodial molecules that could be isolated by bio-guided phytochemical studies.

Low specificity of a malaria rapid diagnostic test during an integrated community case management trial.

INTRODUCTION: Parasitological confirmation before administration of antimalarial treatment has been recommended by the World Health Organization in everyone presenting with symptoms suggestive of malaria at all levels of the health system. METHODS: The authors assessed the performance of a histidine-rich protein 2-based malaria rapid diagnostic test used by community health workers in the context of an integrated approach to diagnosis and treatment for malaria and pneumonia. A total of 525 children below 5 years of age were recruited into the study. Children with fever/history of fever within the last 24 h were tested with the rapid diagnostic test (RDT) and a blood smear was obtained for delayed reading. RESULTS: Overall, the FirstSign™ Malaria Pf (Unimed International Inc, South San Francisco, USA) has shown a high sensitivity profile of 97.9% (95% CI 96.3-98.8), but a low specificity of 53.4% (95% CI 49.1-57.7). The specificity was significantly lower during the high transmission season at 25.4% (95% CI 20.5-31.0) compared to 63.7% (95% CI 57.6-69.4%) at the low transmission season. The negative predictive value (NPV) was 95.4% (95% CI 93.2-96.9) and positive predictive value was 71.7% (95% CI 67.7-75.4). The NPV was significantly higher during the low transmission season at 98.2% (95% CI 95.7-99.3) than compared to 80.0% (95% CI 74.7-84.4) at the high transmission season. CONCLUSION: With such a low specificity, caution should be exercised when using these RDTs for community case management of malaria.

Malaria morbidity in high and seasonal malaria transmission area of Burkina Faso.

BACKGROUND: Malariometric parameters are often primary endpoints of efficacy trials of malaria vaccine candidates. This study aims to describe the epidemiology of malaria prior to the conduct of a series of drug and vaccine trials in a rural area of Burkina Faso. METHODS: Malaria incidence was prospectively evaluated over one year follow-up among two cohorts of children aged 0-5 years living in the Saponé health district. The parents of 1089 children comprising a passive case detection cohort were encouraged to seek care from the local health clinic at any time their child felt sick. Among this cohort, 555 children were randomly selected for inclusion in an active surveillance sub-cohort evaluated for clinical malaria during twice weekly home visits. Malaria prevalence was evaluated by cross-sectional survey during the low and high transmission seasons. RESULTS: Number of episodes per child ranged from 0 to 6 per year. Cumulative incidence was 67.4% in the passive and 86.2% in the active cohort and was highest among children 0-1 years. Clinical malaria prevalence was 9.8% in the low and 13.0% in the high season (p>0.05). Median days to first malaria episode ranged from 187 (95% CI 180-193) among children 0-1 years to 228 (95% CI 212, 242) among children 4-5 years. The alternative parasite thresholds for the malaria case definition that achieved optimal sensitivity and specificity (70-80%) were 3150 parasites/µl in the high and 1350 parasites/µl in the low season. CONCLUSION: Clinical malaria burden was highest among the youngest age group children, who may represent the most appropriate target population for malaria vaccine candidate development. The pyrogenic threshold of parasitaemia varied markedly by season, suggesting a value for alternative parasitaemia levels in the malaria case defintion. Regional epidemiology of malaria described, Sapone area field centers are positioned for future conduct of malaria vaccine trials.

A phase 1b randomized, controlled, double-blinded dosage-escalation trial to evaluate the safety, reactogenicity and immunogenicity of an adenovirus type 35 based circumsporozoite malaria vaccine in Burkinabe healthy adults 18 to 45 years of age.

BACKGROUND: Ad35.CS.01 is a pre-erythrocytic malaria candidate vaccine. It is a codon optimized nucleotide sequence representing the P. falciparum circumsporozoite (CS) surface antigen inserted in a replication deficient Adenovirus 35 backbone. A Phase 1a trial has been conducted in the USA in naïve adults and showed that the vaccine was safe. The aim of this study is to assess the safety and immunogenicity of ascending dosages in sub Saharan Africa. METHODS: A double blind, randomized, controlled, dose escalation, phase Ib trial was conducted in a rural area of Balonghin, the Saponé health district (Burkina Faso). Forty-eight healthy adults aged 18-45 years were randomized into 4 cohorts of 12 to receive three vaccine doses (day 0, 28 and 84) of 10(9), 10(10), 5X10(10), 10(11) vp of Ad35.CS.01 or normal saline by intra muscular injection. Subjects were monitored carefully during the 14 days following each vaccination for non serious adverse events. Severe and serious adverse events were collected throughout the participant study duration (12 months from the first vaccination). Humoral and cellular immune responses were measured on study days 0, 28, 56, 84, 112 and 140. RESULTS: Of the forty-eight subjects enrolled, forty-four (91.7%) received all three scheduled vaccine doses. Local reactions, all of mild severity, occurred in thirteen (27.1%) subjects. Severe (grade 3) laboratory abnormalities occurred in five (10.4%) subjects. One serious adverse event was reported and attributed to infection judged unrelated to vaccine. The vaccine induced both antibody titers and CD8 T cells producing IFNγ and TNFα with specificity to CS while eliciting modest neutralizing antibody responses against Ad35. CONCLUSION: Study vaccine Ad35.CS.01 at four different dose levels was well-tolerated and modestly immunogenic in this population. These results suggest that Ad35.CS.01 should be further investigated for preliminary efficacy in human challenge models and as part of heterologous prime-boost vaccination strategies. TRIAL REGISTRATION: ClinicalTrials.gov NCT01018459 http://clinicaltrials.gov/ct2/show/NCT01018459.

Seasonal performance of a malaria rapid diagnosis test at community health clinics in a malaria-hyperendemic region of Burkina Faso.

BACKGROUND: Treatment of confirmed malaria patients with Artemisinin-based Combination Therapy (ACT) at remote areas is the goal of many anti-malaria programs. Introduction of effective and affordable malaria Rapid Diagnosis Test (RDT) in remote areas could be an alternative tool for malaria case management. This study aimed to assess performance of the OptiMAL dipstick for rapid malaria diagnosis in children under five. METHODS: Malaria symptomatic and asymptomatic children were recruited in a passive manner in two community clinics (CCs). Malaria diagnosis by microscopy and RDT were performed. Performance of the tests was determined. RESULTS: RDT showed similar ability (61.2%) to accurately diagnose malaria as microscopy (61.1%). OptiMAL showed a high level of sensitivity and specificity, compared with microscopy, during both transmission seasons (high & low), with a sensitivity of 92.9% vs. 74.9% and a specificity of 77.2% vs. 87.5%. CONCLUSION: By improving the performance of the test through accurate and continuous quality control of the device in the field, OptiMAL could be suitable for use at CCs for the management and control of malaria.

In vitro antiplasmodial properties of Flacourtia flavescens Willd. (Flacourtiaceae) and Rytigynia canthioides (Benth.) Robyns (Rubiaceae).

The present study was conducted to investigate the in vitro antimalarial activity of Flacourtia flavescens Willd. (Flacourtiaceae) and Rytigynia canthioides (Benth.) Robyns (Rubiaceae). These two plants are used in Benin folk medicine to treat malaria and fever. Antimalarial activity was assayed on fresh clinical isolates of chloroquine resistant Plasmodium falciparum using the in vitro semi-microtest. The results revealed that the IC(50) varied from 1.55 to 22.36µg/ml. F. flavescens hydro methanol extract was more active than R. canthioides. The study demonstrated scientific rationale behind the traditional usage of these plants, however further bioactivity guided phytochemical analyses are necessary to identify the active principles.