Ex vivo drug susceptibility and resistance mediating genetic polymorphisms of Plasmodium falciparum in Bobo-Dioulasso, Burkina Faso.

Malaria remains a leading cause of morbidity and mortality in Burkina Faso, which utilizes artemether-lumefantrine as the principal therapy to treat uncomplicated malaria and seasonal malaria chemoprevention with monthly sulfadoxine-pyrimethamine plus amodiaquine in children during the transmission season. Monitoring the activities of available antimalarial drugs is a high priority. We assessed the ex vivo susceptibility of Plasmodium falciparum to 11 drugs in isolates from patients presenting with uncomplicated malaria in Bobo-Dioulasso in 2021 and 2022. IC50 values were derived using a standard 72 h growth inhibition assay. Parasite DNA was sequenced to characterize known drug resistance-mediating polymorphisms. Isolates were generally susceptible, with IC50 values in the low-nM range, to chloroquine (median IC5010 nM, IQR 7.9-24), monodesethylamodiaquine (22, 14-46) piperaquine (6.1, 3.6-9.2), pyronaridine (3.0, 1.3-5.5), quinine (50, 30-75), mefloquine (7.1, 3.7-10), lumefantrine (7.1, 4.5-12), dihydroartemisinin (3.7, 2.2-5.5), and atovaquone (0.2, 0.1-0.3) and mostly resistant to cycloguanil (850, 543-1,290) and pyrimethamine (33,200, 18,400-54,200), although a small number of outliers were seen. Considering genetic markers of resistance to aminoquinolines, most samples had wild-type PfCRT K76T (87%) and PfMDR1 N86Y (95%) sequences. For markers of resistance to antifolates, established PfDHFR and PfDHPS mutations were highly prevalent, the PfDHPS A613S mutation was seen in 19% of samples, and key markers of high-level resistance (PfDHFR I164L; PfDHPS K540E) were absent or rare (A581G). Mutations in the PfK13 propeller domain known to mediate artemisinin partial resistance were not detected. Overall, our results suggest excellent susceptibilities to drugs now used to treat malaria and moderate, but stable, resistance to antifolates used to prevent malaria.

The impact of anti-malarial markets on artemisinin resistance: perspectives from Burkina Faso.

BACKGROUND: Widespread artemisinin resistance in Africa could be catastrophic when drawing parallels with the failure of chloroquine in the 1970s and 1980s. This article explores the role of anti-malarial market characteristics in the emergence and spread of arteminisin resistance in African countries, drawing on perspectives from Burkina Faso. METHODS: Data were collected through in-depth interviews and focus group discussions. A representative sample of national policy makers, regulators, public and private sector wholesalers, retailers, clinicians, nurses, and community members were purposively sampled. Additional information was also sought via review of policy publications and grey literature on anti-malarial policies and deployment practices in Burkina Faso. RESULTS: Thirty seven in-depth interviews and 6 focus group discussions were conducted. The study reveals that the current operational mode of anti-malarial drug markets in Burkina Faso promotes arteminisin resistance emergence and spread. The factors are mainly related to the artemisinin-based combination therapy (ACT) supply chain, to ACT quality, ACT prescription monitoring and to ACT access and misuse by patients. CONCLUSION: Study findings highlight the urgent requirement to reform current characteristics of the anti-malarial drug market in order to delay the emergence and spread of artemisinin resistance in Burkina Faso. Four recommendations for public policy emerged during data analysis: (1) Address the suboptimal prescription of anti-malarial drugs, (2) Apply laws that prohibit the sale of anti-malarials without prescription, (3) Restrict the availability of street drugs, (4) Sensitize the population on the value of compliance regarding correct acquisition and intake of anti-malarials. Funding systems for anti-malarial drugs in terms of availability and accessibility must also be stabilized.

Nutritional status in young children prior to the malaria transmission season in Burkina Faso and Mali, and its impact on the incidence of clinical malaria.

BACKGROUND: Malaria and malnutrition remain major problems in Sahel countries, especially in young children. The direct effect of malnutrition on malaria remains poorly understood, and may have important implications for malaria control. In this study, nutritional status and the association between malnutrition and subsequent incidence of symptomatic malaria were examined in children in Burkina Faso and Mali who received either azithromycin or placebo, alongside seasonal malaria chemoprevention. METHODS: Mid-upper arm circumference (MUAC) was measured in all 20,185 children who attended a screening visit prior to the malaria transmission season in 2015. Prior to the 2016 malaria season, weight, height and MUAC were measured among 4149 randomly selected children. Height-for-age, weight-for-age, weight-for-height, and MUAC-for-age were calculated as indicators of nutritional status. Malaria incidence was measured during the following rainy seasons. Multivariable random effects Poisson models were created for each nutritional indicator to study the effect of malnutrition on clinical malaria incidence for each country. RESULTS: In both 2015 and 2016, nutritional status prior to the malaria season was poor. The most prevalent form of malnutrition in Burkina Faso was being underweight (30.5%; 95% CI 28.6-32.6), whereas in Mali stunting was most prevalent (27.5%; 95% CI 25.6-29.5). In 2016, clinical malaria incidence was 675 per 1000 person-years (95% CI 613-744) in Burkina Faso, and 1245 per 1000 person-years (95% CI 1152-1347) in Mali. There was some evidence that severe stunting was associated with lower incidence of malaria in Mali (RR 0.81; 95% CI 0.64-1.02; p = 0.08), but this association was not seen in Burkina Faso. Being moderately underweight tended to be associated with higher incidence of clinical malaria in Burkina Faso (RR 1.27; 95% CI 0.98-1.64; p = 0.07), while this was the case in Mali for moderate wasting (RR 1.27; 95% CI 0.98-1.64; p = 0.07). However, these associations were not observed in severely affected children, nor consistent between countries. MUAC-for-age was not associated with malaria risk. CONCLUSIONS: Both malnutrition and malaria were common in the study areas, high despite high coverage of seasonal malaria chemoprevention and long-lasting insecticidal nets. However, no strong or consistent evidence was found for an association between any of the nutritional indicators and the subsequent incidence of clinical malaria.

Effect of adding azithromycin to the antimalarials used for seasonal malaria chemoprevention on the nutritional status of African children.

OBJECTIVES: Mass administration of azithromycin has reduced mortality in children in sub-Saharan Africa but its mode of action is not well characterised. A recent trial found that azithromycin given alongside seasonal malaria chemoprevention was not associated with a reduction in mortality or hospital admissions in young children. We investigated the effect of azithromycin on the nutritional status of children enrolled in this study. METHODS: A total of 19 578 children in Burkina Faso and Mali were randomised to receive either azithromycin or placebo alongside seasonal malaria chemoprevention with sulfadoxine-pyrimethamine plus amodiaquine monthly for three malaria transmission seasons (2014-2016). After each transmission season, anthropometric measurements were collected from approximately 4000 randomly selected children (2000 per country) at a cross-sectional survey and used to derive nutritional status indicators. Binary and continuous outcomes between treatment arms were compared by Poisson and linear regression. RESULTS: Nutritional status among children was poor in both countries with evidence of acute and chronic malnutrition (24.9-33.3% stunted, 15.8-32.0% underweight, 7.2-26.4% wasted). There was a suggestion of improvement in nutritional status in Burkina Faso and deterioration in Mali over the study period. At the end of each malaria transmission season, nutritional status of children did not differ between treatment arms (seasonal malaria chemoprevention plus azithromycin or placebo) in either the intention-to-treat or per-protocol analyses (only children with at least three cycles of SMC in the current intervention year). CONCLUSIONS: The addition of azithromycin to seasonal malaria chemoprevention did not result in an improvement of nutritional outcomes in children in Burkina Faso and Mali.

OBJECTIFS: L'administration massive d'azithromycine a réduit la mortalité infantile en Afrique subsaharienne mais son mode d'action n'est pas bien caractérisé. Un essai récent a révélé que l'azithromycine administrée parallèlement à la chimioprévention du paludisme saisonnier n'était pas associée à une réduction de la mortalité ou des hospitalisations chez les jeunes enfants. Nous avons étudié l'effet de l'azithromycine sur l'état nutritionnel des enfants inscrits à cette étude. MÉTHODES: 19.578 enfants au Burkina Faso et au Mali ont été randomisés pour recevoir soit de l'azithromycine soit un placebo parallèlement à une chimioprévention du paludisme saisonnier avec du sulfadoxine-pyriméthamine plus de l'amodiaquine par mois pendant trois saisons de transmission du paludisme (2014-2016). Après chaque saison de transmission, des mesures anthropométriques ont été recueillies auprès d'environ 4.000 enfants sélectionnés au hasard (2.000 par pays) lors d'une enquête transversale et utilisées pour dériver des indicateurs de l'état nutritionnel. Les résultats binaires et continus entre les bras de traitement ont été comparés par la régression linéaire et de Poisson. RÉSULTATS: L'état nutritionnel des enfants était médiocre dans les deux pays avec des signes de malnutrition aiguë et chronique (24,9 à 33,3% de retard de croissance, 15,8 à 32,0% d'insuffisance pondérale, 7,2 à 26,4% d'émaciation). Il a été suggéré une amélioration de l'état nutritionnel au Burkina Faso et une détérioration au Mali au cours de la période d'étude. A la fin de chaque saison de transmission du paludisme, l'état nutritionnel des enfants ne différait pas entre les bras de traitement (chimioprévention contre le paludisme saisonnier plus azithromycine ou placebo) dans les analyses en intention de traiter ou selon le protocole (seulement les enfants avec au moins trois cycles de chimioprévention dans l'année d'intervention en cours). CONCLUSIONS: L'ajout d'azithromycine à la chimioprévention du paludisme saisonnier n'a pas entraîné d'amélioration des résultats nutritionnels chez les enfants au Burkina Faso et au Mali.

Plasmodium transmission blocking activities of Vernonia amygdalina extracts and isolated compounds.

BACKGROUND: Medicinal plants are a validated source for discovery of new leads and standardized herbal medicines. The aim of this study was to assess the activity of Vernonia amygdalina leaf extracts and isolated compounds against gametocytes and sporogonic stages of Plasmodium berghei and to validate the findings on field isolates of Plasmodium falciparum. METHODS: Aqueous (Ver-H2O) and ethanolic (Ver-EtOH) leaf extracts were tested in vivo for activity against sexual and asexual blood stage P. berghei parasites. In vivo transmission blocking effects of Ver-EtOH and Ver-H2O were estimated by assessing P. berghei oocyst prevalence and density in Anopheles stephensi mosquitoes. Activity targeting early sporogonic stages (ESS), namely gametes, zygotes and ookinetes was assessed in vitro using P. berghei CTRPp.GFP strain. Bioassay guided fractionation was performed to characterize V. amygdalina fractions and molecules for anti-ESS activity. Fractions active against ESS of the murine parasite were tested for ex vivo transmission blocking activity on P. falciparum field isolates. Cytotoxic effects of extracts and isolated compounds vernolide and vernodalol were evaluated on the human cell lines HCT116 and EA.hy926. RESULTS: Ver-H2O reduced the P. berghei macrogametocyte density in mice by about 50% and Ver-EtOH reduced P. berghei oocyst prevalence and density by 27 and 90%, respectively, in An. stephensi mosquitoes. Ver-EtOH inhibited almost completely (>90%) ESS development in vitro at 50 µg/mL. At this concentration, four fractions obtained from the ethylacetate phase of the methanol extract displayed inhibitory activity >90% against ESS. Three tested fractions were also found active against field isolates of the human parasite P. falciparum, reducing oocyst prevalence in Anopheles coluzzii mosquitoes to one-half and oocyst density to one-fourth of controls. The molecules and fractions displayed considerable cytotoxicity on the two tested cell-lines. CONCLUSIONS: Vernonia amygdalina leaves contain molecules affecting multiple stages of Plasmodium, evidencing its potential for drug discovery. Chemical modification of the identified hit molecules, in particular vernodalol, could generate a library of druggable sesquiterpene lactones. The development of a multistage phytomedicine designed as preventive treatment to complement existing malaria control tools appears a challenging but feasible goal.

Prevalence of SARS-CoV-2 and co-infection with malaria during the first wave of the pandemic (the Burkina Faso case).

Africa accounts for 1.5% of the global coronavirus disease 2019 (COVID-19) cases and 2.7% of deaths, but this low incidence has been partly attributed to the limited testing capacity in most countries. In addition, the population in many African countries is at high risk of infection with endemic infectious diseases such as malaria. Our aim is to determine the prevalence and circulation of SARS-CoV-2 variants, and the frequency of co-infection with the malaria parasite. We conducted serological tests and microscopy examinations on 998 volunteers of different ages and sexes in a random and stratified population sample in Burkina-Faso. In addition, nasopharyngeal samples were taken for RT-qPCR of SARS-CoV-2 and for whole viral genome sequencing. Our results show a 3.2 and a 2.5% of SARS-CoV-2 seroprevalence and PCR positivity; and 22% of malaria incidence, over the sampling period, with marked differences linked to age. Importantly, we found 8 cases of confirmed co-infection and 11 cases of suspected co-infection mostly in children and teenagers. Finally, we report the genome sequences of 13 SARS-CoV-2 isolates circulating in Burkina Faso at the time of analysis, assigned to lineages A.19, A.21, B.1.1.404, B.1.1.118, B.1 and grouped into clades; 19B, 20A, and 20B. This is the first population-based study about SARS-CoV-2 and malaria in Burkina Faso during the first wave of the pandemic, providing a relevant estimation of the real prevalence of SARS-CoV-2 and variants circulating in this Western African country. Besides, it highlights the non-negligible frequency of co-infection with malaria in African communities.

Predicting the public health impact of a malaria transmission-blocking vaccine.

Transmission-blocking vaccines that interrupt malaria transmission from humans to mosquitoes are being tested in early clinical trials. The activity of such a vaccine is commonly evaluated using membrane-feeding assays. Understanding the field efficacy of such a vaccine requires knowledge of how heavily infected wild, naturally blood-fed mosquitoes are, as this indicates how difficult it will be to block transmission. Here we use data on naturally infected mosquitoes collected in Burkina Faso to translate the laboratory-estimated activity into an estimated activity in the field. A transmission dynamics model is then utilised to predict a transmission-blocking vaccine's public health impact alongside existing interventions. The model suggests that school-aged children are an attractive population to target for vaccination. Benefits of vaccination are distributed across the population, averting the greatest number of cases in younger children. Utilising a transmission-blocking vaccine alongside existing interventions could have a substantial impact against malaria.

Insecticide resistance profiles in malaria vector populations from Sud-Kivu in the Democratic Republic of the Congo.

BACKGROUND: Insecticide resistance has become a widespread problem causing a decline in the effectiveness of vector control tools in sub-Saharan Africa. In this situation, ongoing monitoring of vector susceptibility to insecticides is encouraged by the WHO to guide national malaria control programmes. Our study was conducted from April to November 2018 in Tchonka (Sud-Kivu, Democratic Republic of the Congo) and reported primary data on the resistance status of Anopheles funestus and Anopheles gambiae. METHODS: Insecticide susceptibility bioassays were performed on wild populations of A. funestus and A. gambiae using WHO insecticide-impregnated papers at discriminating concentration. In addition, PCR was performed to identify mosquito species and to detect kdr and ace-1R mutations involved in insecticide resistance. RESULTS: Bioassay results show resistance to all tested insecticides except pirimiphos-methyl, propoxur, fenitrothion and malathion with a mortality rate ranging from 95.48 to 99.86%. The addition of piperonyl butoxide (PBO) increased the susceptibility of vectors to deltamethrin and alpha-cypermethrin by exhibiting a mortality ranging from 91.50 to 95.86%. The kdr mutation was detected at high frequencies (approximately 0.98) within A. gambiae while ace-1R was not detected. CONCLUSIONS: This study provides useful data on the insecticide resistance profiles of malaria vector populations to better manage vector control. Our results highlight that, despite the high level of resistance, organophosphorus compounds and pyrethroids + PBO remain effective against the vectors.

In Vivo Antiplasmodial Activity of Two Sahelian Plant Extracts on Plasmodium berghei ANKA Infected NMRI Mice.

Up to now, the control of malaria remains a challenge. The World Health Organization (WHO) recommends the use of artemisinin-based combination therapies (ACTs) for uncomplicated malaria treatment. Despite this guideline, many people in Burkina Faso use herbal medicine as primary treatment against malaria. The aim of this study was to assess the in vivo activity of Guiera senegalensis J. F. Gmel and Bauhinia rufescens Lam. leaves extracts against Plasmodium berghei ANKA. A four-day treatment of leaves decoction of each plant was administrated orally to 7 groups of six NMRI (Naval Medical Research Institute) mice infected with Plasmodium berghei ANKA strain. The control group received distilled water as treatment while the treated groups each received daily 100, 250, and 500 mg extract/kg body weight. Thin blood smears were performed on day five and the percentage of reduction of parasitaemia was determined compared to the control. The percentages of reduction of the parasitaemia at the doses of 100, 250, and 500 mg extract/kg body weight were, respectively, 57.5%, 35.9%, and 44.9% for Guiera senegalensis and 50.6%, 22.2%, and 25.7% for Bauhinia rufescens. Our findings on antiplasmodial activity of these two plants justify the traditional use by local populations against malaria. Thus, the isolation of the active compounds from these two plants is suggested for possible antimalarial candidate drugs.

Plasmodium falciparum msp1 and msp2 genetic diversity and allele frequencies in parasites isolated from symptomatic malaria patients in Bobo-Dioulasso, Burkina Faso.

BACKGROUND: In Burkina Faso, malaria remains the overall leading cause of morbidity and mortality accounting for 35.12% of consultations, 40.83% of hospitalizations and 37.5% of deaths. Genotyping of malaria parasite populations remains an important tool to determine the types and number of parasite clones in an infection. The present study aimed to evaluate the merozoite surface protein 1 (msp1) and merozoite surface protein 2 (msp2) genetic diversity and allele frequencies in Bobo-Dioulasso, Burkina Faso. METHOD: Dried blood spots (DBS) were collected at baseline from patients with uncomplicated malaria in urban health centers in Bobo-Dioulasso. Parasite DNA was extracted using chelex-100 and species were identified using nested PCR. Plamodium falciparum msp1 and msp2 genes were amplified by nested polymerase chain reaction (PCR) and PCR products were analyzed by electrophoresis on a 2.5% agarose gel. Alleles were categorized according to their molecular weight. RESULTS: A total of 228 blood samples were analyzed out of which 227 (99.9%) were confirmed as P. falciparum-positive and one sample classified as mixed infection for P. malaria and P. falciparum. In msp1, the K1 allelic family was predominant with 77.4% (162/209) followed respectively by the MAD20 allelic family with 41.3% and R033 allelic family with 36%. In msp2, the 3D7 allelic family was the most frequently detected with 93.1 % compared to FC27 with 41.3%. Twenty-one different alleles were observed in msp1 with 9 alleles for K1, 8 alleles for MAD20 and 4 alleles for R033. In msp2, 25 individual alleles were detected with 10 alleles for FC27 and 15 alleles for 3D7. The mean multiplicity of falciparum infection was 1.95 with respectively 1.8 (1.76-1.83) and 2.1 (2.03-2.16) for msp1 and msp2 (P = 0.01). CONCLUSIONS: Our study showed high genetic diversity and allelic frequencies of msp1 and msp2 in Plasmodium falciparum isolates from symptomatic malaria patients in Bobo-Dioulasso.

Neemazal ® as a possible alternative control tool for malaria and African trypanosomiasis?

BACKGROUND: Research efforts to identify possible alternative control tools for malaria and African trypanosomiasis are needed. One promising approach relies on the use of traditional plant remedies with insecticidal activities. METHODS: In this study, we assessed the effect of blood treated with different doses of NeemAzal ® (NA, neem seed extract) on mosquitoes (Anopheles coluzzii) and tsetse flies (Glossina palpalis gambiensis) (i) avidity to feed on the treated blood, (ii) longevity, and (iii) behavioural responses to human and calf odours in dual-choice tests. We also gauged NeemAzal ® toxicity in mice. RESULTS: In An. coluzzii, the ingestion of NA in bloodmeals offered by membrane feeding resulted in (i) primary antifeedancy; (ii) decreased longevity; and (iii) reduced response to host odours. In G. palpalis gambiensis, NA caused (i) a knock-down effect; (ii) decreased or increased longevity depending on the dose; and (iii) reduced response to host stimuli. In both cases, NA did not affect the anthropophilic rate of activated insects. Overall, the most significant effects were observed with NA treated bloodmeals at a dose of 2000 µg/ml for mosquitoes and 50 µg/ml for tsetse flies. Although no mortality in mice was observed after 14 days of follow-up at oral doses of 3.8, 5.6, 8.4 and 12.7 g/kg, behavioural alterations were noticed at doses above 8 g/kg. CONCLUSION: This study revealed promising activity of NA on A. coluzzii and G. palpalis gambiensis but additional research is needed to assess field efficacy of neem products to be possibly integrated in vector control programmes.