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    Biosorption of Pb(II) ions from aqueous solution using alginates extracted from Djiboutian seaweeds and deposited on silica particles
    (Pure Appl. Chem, 2019) Aden, Moumin; Husson, Jérôme; Monney, Sandrine; Franchi, Marielle
    High-molecular alginates were extracted from Djiboutian brown seaweeds, Sargassum sp. (S) and Turbinaria (T) and isolated as sodium salts in 31.0 and 42.7% yield by weight. 1H NMR analysis of the uronic acid block-structure indicates mannuronic/guluronic M/G ratios of 0.49 and 3.0 for the alginates extracts, respectively. The resulting alginates were deposited onto native Aerosil 200 silica, amine-functionalized and carboxyl-functionalized silica particles to enhance the mechanical strength providing Alg.(T/S)+SiO2) Alg.(T/S)+SiO2NH2) and Alg.(T)+SiO2CO2H) composites. Taking Pb(II) as examples for toxic heavy metal ions, the effects of the pH, adsorption kinetics, and isotherms have been studied systematically. The best uptake achieved was 585 mg Pb2+ ion/g using Alg.S+SiO2NH2. Furthermore, the Pb(II) ions were successfully desorbed in several cycles from Alg.T+SiO2 using 0.5 M hydrochloric acid. Therefore, Alg.T+SiO2 may be considered as a low-cost biosorbent that quickly adsorbs and easily desorbs analyte lead ions. A comparison of the adsorption capacity of our biopolymer-coated particles with that of other adsorbents reported in the literature reveals that our materials are among the best performing for the adsorption of Pb(II).
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    Does Tap Water Quality Compromise the Production of Aedes Mosquitoes in Genetic Control Projects?
    (Insects, 2021-01-12) Mamai, Wadaka; Maiga, Hamidou; Somda, Nanwintoum Sévérin Bimbilé
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    Small-scale release of non-gene drive mosquitoes in Burkina Faso: from engagement implementation to assessment, a learning journey
    (Malaria Journal, 2021-10-09) Toe, Lea Pare; Barry, Nourou; Ky, Anselme D.; Kekele, Souleymane
    Background: Innovative tools are needed to complement the existing approach for malaria elimination. Gene drive mosquitoes are one potential new technology in the control of malaria vectors. Target Malaria is one of the research projects developing this technology, and in July 2019, the project proceeded to an important step for this evaluation pathway: the small-scale release of non-gene drive sterile male mosquitoes in a village in Burkina Faso. In addition to the entomological and laboratory work to prepare for this important milestone, significant community and stake holder engagement work was done. The existing guidelines on gene drive mosquito provide an overall framework for such engagement work. However, they do not provide a road map on how to proceed or what benchmarks should be used to assess this work. Methods: This study provides a review of engagement activities relevant to field trials on non-gene drive genetically modified mosquitoes as well as an assessment framework—using both qualitative and quantitative studies as well as an audit procedure. The latter was implemented to evaluate whether the release activities could proceed with the appropriate level of agreement from the community. Results: This paper shows the importance of this first phase of work to innovate and learn about engagement processes for responsible research in the field of genetic approaches for malaria vector control. The function of these assessments is crucial for the learning agenda. The assessments demonstrated ways to increase understanding and ensure effective progress with field studies and, therefore, the pathway for responsible research. Conclusion: Gene drive technology is increasingly considered as a promising approach to control vector borne diseases, in particular malaria. Stakeholders’ involvement in this research process is one of the recurring requirements in international guidance documents. With this paper Target Malaria offers an opportunity to explore the practical achievements and challenges of stakeholder engagement during early phases of a technology evaluation, and in particular how it implemented an assessment framework to learn from its experience.
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    Intraspecific Transcriptome Variation and Sex-Biased Expression in Anopheles arabiensis
    (Genome Biol. Evol., 2021-08-22) Jayaswal, Vivek; Ndo, Cyrille; Hsiu-Ching, Ma
    The magnitude and functional patterns of intraspecific transcriptional variation in the anophelines, including those of sex-biased genes underlying sex-specific traits relevant for malaria transmission, remain understudied. As a result, how changes in expression levels drive adaptation in these species is poorly understood. We sequenced the female, male, and larval transcriptomes of three populations of Anopheles arabiensis from Burkina Faso. One-third of the genes were differentially expressed between populations, often involving insecticide resistance-related genes in a sample type-specific manner, and with the females showing the largest number of differentially expressed genes. At the genomic level, the X chromosome appears depleted of differentially expressed genes compared with the autosomes, chromosomes harboring in versions do not exhibit evidence for enrichment of such genes, and genes that are top contributors to functional enrichment patterns of population differentiation tend to be clustered in the genome. Further, the magnitude of variation for the sex expression ratio across populations did not substantially differ between male- and female-biased genes, except for some populations in which male-limited expressed genes showed more variation than their female counterparts. In fact, female-biased genes exhibited a larger level of inter population variation than male-biased genes, both when assayed in males and females. Beyond uncovering the extensive adaptive potential of transcriptional variation in An. Arabiensis, our findings suggest that the evolutionary rate of changes in expression levels on the X chromosome exceeds that on the autosomes, while pointing to female-biased genes as the most variable component of the An. Arabiensis transcriptome
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    Biodiversité de la flore fongique isolée au service de réanimation du Centre Hospitalo-Universitaire Souro Sanou de Bobo-Dioulasso, Burkina Faso
    (Pan African Medical Journal, 2021-03-23) Sangare, Ibrahim; Bisseye, Cyrille; Matotou, Hadry Roger Sib
    Biodiversité de la flore fongique isolée au service de réanimation du Centre Hospitalo-Universitaire Souro Sanou de Bobo-Dioulasso, Burkina Faso Biodiversity of isolated fungal flora at the reanimation service of the University Hospital Souro Sanou of Bobo-Dioulasso, Burkina Faso Hadry Roger Sibi Matotou1,2,&, Ibrahim Sangare1,3 , Cyrille Bisseye4 , Marielle Karine Bouyou Akotet2 , Sanata Bamba1,3 1 Institut Supérieur des Sciences de la Santé, Université Nazi Boni, 01 BP 1091, Bobo-Dioulasso, Burkina Faso, 2Université des Sciences de la Santé, Département de Parasitologie-Mycologie, BP 4009 Libreville, Gabon, 3 Service de Parasitologie Mycologie, Département des Laboratoires, Centre Hospitalier Universitaire Souro Sanou, 01 BP 676, Bobo-Dioulasso, Burkina Faso, 4 Laboratoire de Biologie Moléculaire et Cellulaire, Université des Sciences et Techniques de Masuku, BP 943, Franceville, Gabon
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    Prevalence and factors associated of Trichomonas vaginalis infection among pregnant women in Bobo Dioulasso, Burkina Faso
    (Annals of Parasitology, 2021-04-15) SANGARÉ, Ibrahim; CISSÉ, Mamoudou; SIRIMA, Constant
    Epidemiological studies of vaginalis trichomonosis, especially in pregnant women are rare in Africa due to the lack of screening programs. The present study aimed to assess the prevalence of T. vaginalis infection and its associated factors in pregnant women who attended the antenatal care clinics in three primary health centers of Bobo Dioulasso. We carried out a cross-sectional study for descriptive and analytical purposes from February to April 2015 in pregnant women seen in prenatal consultations. The study took place in 3 primary public health centers: Guimbi (Central Urban), Bolomakoté (Peri-urban) and Yéguérésso (rural). The trophozoites of Trichomonas vaginalis was carried out by microscopy on vaginal swabs and urine samples. Sociodemographic, obstetric and biological variables were also collected. A total of 315 pregnant women were included in the study. The overall prevalence of urogenital trichomonosis was 3.2%. It was 1.9% in Guimbi, 2.9% in Bolomakoté, and 4.7% in Yéguérésso. The prevalence of HIV infection was 2.2%. Married women were less exposed to T. vaginalis infection than single women (p=0.03). The prevalence of urogenital trichomonosis obtained was considered lower compared to the previously reported from Burkina Faso. Thus, it is essential to extend this study to the whole country periodically by integrating other STIs not subject to a surveillance system and by integrating molecular epidemiology tools
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    A non‑destructive sugar‑feeding assay for parasite detection and estimating the extrinsic incubation period of Plasmodium falciparum in individual mosquito vectors
    (Scientific Reports, 2021-05-29) Guissou, Edwige; Waite, Jessica L.; Jones, Matthew
    Despite its epidemiological importance, the time Plasmodium parasites take to achieve development in the vector mosquito (the extrinsic incubation period, EIP) remains poorly characterized. A novel non‑destructive assay designed to estimate EIP in single mosquitoes, and more broadly to study Plasmodium–Anopheles vectors interactions, is presented. The assay uses small pieces of cotton wool soaked in sugar solution to collect malaria sporozoites from individual mosquitoes during sugar feeding to monitor infection status over time. This technique has been tested across four natural malaria mosquito species of Africa and Asia, infected with Plasmodium falciparum (six field isolates from gametocyte‑infected patients in Burkina Faso and the NF54 strain) and across a range of temperatures relevant to malaria transmission in field conditions. Monitoring individual infectious mosquitoes was feasible. The estimated median EIP of P. falciparum at 27 °C was 11 to 14 days depending on mosquito species and parasite isolate. Long‑term individual tracking revealed that sporozoites transfer onto cotton wool can occur at least until day 40 post‑infection. Short individual EIP were associated with short mosquito lifespan. Correlations between mosquito/parasite traits often reveal trade‑offs and constraints and have important implications for understanding the evolution of parasite transmission strategies
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    Clock genes and environmental cues coordinate Anopheles pheromone synthesis, swarming, and mating
    (Science, 2021-01-22) Wang, Guandong; Vega-Rodríguez, Joel; Diabate, Abdoulaye
    Anopheles mating is initiated by the swarming of males at dusk followed by females flying into the swarm. Here, we show that mosquito swarming and mating are coordinately guided by clock genes, light, and temperature. Transcriptome analysis shows up-regulation of the clock genes period (per) and timeless (tim) in the head of field-caught swarming Anopheles coluzzii males. Knockdown of per and tim expression affects Anopheles gambiae s.s. and Anopheles stephensi male mating in the laboratory, and it reduces male An. coluzzii swarming and mating under semifield conditions. Light and temperature affect mosquito mating, possibly by modulating per and/or tim expression. Moreover, the desaturase gene desat1 is up-regulated and rhythmically expressed in the heads of swarming males and regulates the production of cuticular hydrocarbons, including heptacosane, which stimulates mating activity
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    Predicting the public health impact of a malaria transmission-blocking vaccine
    (Nature Communications, 2021-03-08) Mesa, Daniela Olivera; Da, Dari F.; Challenger, Joseph D
    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
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    Improved BioGents® Sentinel trap with heat (BGSH) for outdoor collections of Anopheline species in Burkina Faso and Mali, West Africa
    (Parasites Vectors, 2021-01-28) Guindo, Amadou; Epopa, Patric Stephane; Sidy Doumbia, Sidy
    Background: Since the late 1990s, malaria control programmes have relied extensively on mass bednet distribution and indoor residual spraying. Both interventions use pesticides and target mosquitoes coming indoors either to feed or to rest. Unfortunately, these intensified vector control campaigns have resulted in mosquito populations with high levels of resistance to most of the chemical compounds used against them and which are increasingly exophagic and exophillic, hence difficult to monitor indoors. Consequently, there is an urgent need for novel tools to sample outdoor anopheline populations for monitoring interventions and disease surveillance programmes. Methodologies: In this study, we tested several modifications and configurations of the BioGents® Sentinel (BGS) trap, designed with the aim to increase its efficacy for sampling malaria vector species. Traps were used with chemical attractants and CO2, and the impacts of trap position, trap colour contrast combination and the addition of a heat source were tested in two studies conducted in the Sudano-Sahelian region of Burkina Faso and Mali. Results: The results show that of all the configurations tested, the addition of a heat source to the BGS trap with the original colour combination and an upward positioning resulted in a 1.8- and 5.9-fold increase in host-seeking Anopheles gambiae (s.l.) females in the experiments performed in Burkina Faso and Mali, respectively. BGS with heat traps, referred to as BGSH traps, captured An. gambiae (s.l.), An. pharoensis, An. coustani, Culex and Mansonia spp. Importantly, the results suggest that their efficacy does not depend on the close proximity of nearby hosts in houses. Conclusions: The results suggest that BGSH traps can be an effective scalable tool for sampling outdoor anopheline vector populations. Further developments enabling CO2 and heat generation for longer periods of time would further improve the trap's versatility for large-scale surveillance programmes.
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    Ripple effects of research capacity strengthening: a study of the effects of a project to support test facilities in three African countries towards Good Laboratory Practice certification
    (Gates Open Research, 2022-03-23) Begg, Sara; Wright, Alexandra; Small, Graham
    Background: Strengthening capacity for public health research is essential to the generation of high-quality, reliable scientific data. This study focuses on a research capacity strengthening project supporting seven test facilities in Africa conducting studies on mosquito vector control products towards Good Laboratory Practice (GLP) certification. It captures the primary effects of the project on each facility’s research capacity, the secondary effects at the individual and institutional level, and the ripple effects that extend beyond the research system. The relationships between effects at different levels are identified and compared to an existing framework for the evaluation of research capacity strengthening initiatives. Methods: To capture the views of individuals engaged in the project at all levels within each facility, a maximum-variation purposive sampling strategy was used. This allowed triangulation between different data sources. Semi-structured interviews were conducted with individuals in three facilities and a combination of email and remote video-call interviews were conducted with individuals at two further facilities. Results: We found that, despite a focus of the GLP certification project at the institutional level, the project had effects also at individual (including enhanced motivation, furtherment of careers) and national/international levels (including development of regional expertise). In addition, we detected ripple effects of the project which extended beyond the research system. Conclusion: This study shows that research capacity strengthening interventions that are focussed on institutional level goals require actions also at individual and national/international levels. The effects of engagement at all three levels can be amplified by collaborative actions at the national/international level. These findings show that research capacity strengthening projects must develop plans that address and evaluate impact at all three levels. Capturing the ripple effects of investment in research capacity strengthening should also be planned for from the beginning of projects to support further engagement of all stakeholders.
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    Multi-site comparison of factors influencing progress of African insecticide testing facilities towards an international Quality Management System certification
    (PLOS ONE, 2021-11-15) Begg, Sara; Wright, Alex; Smal, Graham
    Insecticidal mosquito vector control products are vital components of malaria control pro grammes. Test facilities are key in assessing the effectiveness of vector control products against local mosquito populations, in environments where they will be used. Data from these test facilities must be of a high quality to be accepted by regulatory authorities, including the WHO Prequalification Team for vector control products. In 2013–4, seven insecticide testing facilities across sub-Saharan Africa, with technical and financial support from Innovative Vector Control Consortium (IVCC), began development and implementation of quality management system compliant with the principles of Good Laboratory Practice (GLP) to improve data quality and reliability. Methods and principle findings We conducted semi-structured interviews, emails, and video-call interviews with individuals at five test facilities engaged in the IVCC-supported programme and working towards or having achieved GLP. We used framework analysis to identify and describe factors affecting progress towards GLP. We found that eight factors were instrumental in progress, and that test facilities had varying levels of control over these factors. They had high control over the training programme, project planning, and senior leadership support; medium control over infrastructure development, staff structure, and procurement; and low control over funding the availability and accessibility of relevant expertise. Collaboration with IVCC and other partners was key to overcoming the challenges associated with low and medium control factors. Conclusion For partnership and consortia models of research capacity strengthening, test facilities can use their own internal resources to address identified high-control factors. Project plans should allow additional time for interaction with external agencies to address medium-control factors, and partners with access to expertise and funding should concentrate their efforts on supporting institutions to address low-control factors. In practice, this includes planning for financial sustainability at the outset, and acting to strengthen national and regional training capacity.
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    A mating-induced reproductive gene promotes Anopheles tolerance to Plasmodium falciparum infection
    (PLoS Pathog, 2020-12-21) Marcenac, Perrine; Shaw, W. Robert; Kakani, Evdoxia G.
    Anopheles mosquitoes have transmitted Plasmodium parasites for millions of years, yet it remains unclear whether they suffer fitness costs to infection. Here we report that the fecundity of virgin and mated females of two important vectors—Anopheles gambiae and Anopheles stephensi—is not affected by infection with Plasmodium falciparum, demonstrating that these human malaria parasites do not inflict this reproductive cost on their natural mosquito hosts. Additionally, parasite development is not impacted by mating status. However, in field studies using different P. falciparum isolates in Anopheles coluzzii, we find that MatingInduced Stimulator of Oogenesis (MISO), a female reproductive gene strongly induced after mating by the sexual transfer of the steroid hormone 20-hydroxyecdysone (20E), protects females from incurring fecundity costs to infection. MISO-silenced females produce fewer eggs as they become increasingly infected with P. falciparum, while parasite development is not impacted by this gene silencing. Interestingly, previous work had shown that sexual transfer of 20E has specifically evolved in Cellia species of the Anopheles genus, driving the co-adaptation of MISO. Our data therefore suggest that evolution of male-female sexual interactions may have promoted Anopheles tolerance to P. falciparum infection in the Cellia subgenus, which comprises the most important malaria vectors.
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    Short Persistence and Vector Susceptibility to Ficam 80WP (bendiocarb active ingredient) During Pilot Application of Indoor Residual Spraying in Burkina Faso, West Africa
    (Journal of Medical Entomology, 2020-11-09) Hien, Aristide Sawdetuo; Soma, Dieudonné Diloma; Somé, Fabrice Anyirekun
    Indoor residual spraying (IRS) was applied in addition to the use of long-lasting insecticidal nets in the SouthWest in Burkina Faso, where Anopheles gambiae s.l. the major malaria vector was resistant to pyrethroids. This study was designed to evaluate the efficacy and residual life of bendiocarb (active ingredient) used forspraying on different wall surfaces (mud and cement). Cone bioassays were done monthly with the susceptible An. gambiae ‘Kisumu’ strain and the local wild populations to determine the duration for which insecticide was effective in killing mosquitoes. Cone bioassay data showed low efficacy and short persistence ofbendiocarb applied on mud and cement walls, lasting 2 mo with the susceptible insectary strain and less than1 mo with An. gambiae wild populations. In addition, WHO tube assays confirmed resistance of An. gambiaewild populations to 0.1% bendiocarb with mortality rates less than 80% in both study sites (sprayed and unsprayed sites). The pilot study of IRS with bendiocarb showed that the residual efficacy of bendiocarb was veryshort, and resistance to bendiocarb was confirmed in wild populations of An. gambiae s.l. Therefore, Ficam 80WP was not suitable for IRS in this area due to the short residual duration related mainly to vectors resistanceto bendiocarb. While waiting for innovative malaria control tool, alternative insecticide (organophosphate orneonicotinoid classes) or combinations of insecticides have to be used for insecticide resistance managementin Burkina Faso.
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    Plasmodium infection induces cross-reactive antibodies to carbohydrate epitopes on the SARS-CoV-2 Spike protein
    (medRxiv, 2021) Lapidus, Sarah; Liu, Feimei; Casanovas-Massana, Arnau
    Individuals with acute malaria infection generated high levels of antibodies that cross-react with the SARS-CoV-2 Spike protein. Cross-reactive antibodies specifically recognized the sialic acid moiety on N-linked glycans of the Spike protein and do not neutralize in vitro SARS-CoV-2. Sero-surveillance is critical for monitoring and projecting disease burden and risk during the pandemic; however, routine use of Spike protein-based assays may overestimate SARS-CoV-2 exposure and population-level immunity in malaria-endemic countries
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    Entomological baseline data collection and power analyses in preparation of a mosquito swarm-killing intervention in south-western Burkina Faso
    (Malaria Journal, 2021-08-10) Niang, Abdoulaye; Sawadogo, Simon P.; Millogo, Abdoul A.
    Background: Insecticides are currently the main tools used to reduce the transmission of malaria; therefore, the development of resistance to insecticides in malaria vectors is of major concern for malaria control. The resistance level to pyrethroids is particularly high in the Western region of Burkina Faso and may afect the efcacy of insecticidal bed nets and indoor residual spraying. Adult mosquito swarming and other nocturnal behaviours exhibit spatial and temporal patterns that suggest potential vulnerability to targeted space spraying with efective insecticides. Indeed, targeted space-spraying against adult mosquito swarms has been used to crash mosquito populations and disrupt malaria transmission. Methods: Prior to impact assessment of swarm killing, a baseline data collection was conducted from June to November 2016 in 10 villages divided into two areas in western Burkina Faso. The data considered both ecological and demographic characteristics to monitor the key entomological parameters. Results: The mean number of swarms observed was 35 per village, ranging from 25 to 70 swarms according to the village. Female density in both areas varied signifcantly as a function of the village and the period of collection. The human biting rate was signifcantly afected by the period of collection and depended upon whether the collection was carried out indoors or outdoors. Averages of parity rate were high in both areas for all periods of collection, ranging from 60 to 90%. These values ranged from 80 to 100% for inseminated females. Sporozoite rates ranged between 1.6 and 7.2% depending upon the village. The molecular identifcation of resting and swarming mosquitoes showed the presence of the three major malaria vectors in Burkina Faso, but in diferent proportions for each village. Conclusions: The distribution of the potential swarm markers and swarms in villages suggested that swarms are clustered across space, making intervention easier. Power simulations showed that the direct sampling of swarms provides the highest statistical power, thereby reducing the number of villages needed for a trial
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    Snakebite frequencies and envenomation case management in primary health centers of the Bobo-Dioulasso health district (Burkina Faso) from 2014 to 2018
    (Trans R Soc Trop Med Hyg, 2021-09-09) Bamogoa, Rabila; Thiam, Massamba; Nikièma, Achille Sindimbasba
    Background: Snakebite envenomation is a significant public health problem in Burkina Faso. Our study describes the epidemiological and therapeutic aspects of snakebite cases at primary health centers in Houet Province, which is located in the western area of Burkina Faso. Methods: We conducted a retrospective study of 664 snakebite cases occurring at 10 primary health centers in Houet Province from January 2014 to December 2018. Data were collected from the patient consultation recording database registry system. Results: Affected individuals had a male/female ratio of 1.31. The lowest annual incidences (0.02 [95% CI – 0.01 to 0.05] and 0.24 [95% CI 0.05 to 0.43]) were observed in the urban primary health centers of Bolomakoté and Sarfalao, respectively. Rural primary health centers in Nasso in 2016 and in Soumousso in 2014 had the highest annual incidence (13.80 [95% CI 7.59 to 20.00] and 3.92 [95% CI 2.99 to 4.86], respectively). Of the 664 registered snakebite victims, none received antivenom immunotherapy treatment. Conclusion: Our study shows that snakebite envenomation incidents are common at the 10 primary health centers in Houet Province. Furthermore, despite the lack of antivenom and often inadequate treatment at these primary health centers, they remain the first point of care for snakebite victims
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    Contrasting efects of the alkaloid ricinine on the capacity of Anopheles gambiae and Anopheles coluzzii to transmit Plasmodium falciparum
    (Parasites Vectors, 2021-09-15) Hien, Domonbabele F. D. S.; Paré, Prisca S. L.; Cooper, Amanda
    Background: Besides feeding on blood, females of the malaria vector Anopheles gambiae sensu lato readily feed on natural sources of plant sugars. The impact of toxic secondary phytochemicals contained in plant-derived sugars on mosquito physiology and the development of Plasmodium parasites remains elusive. The focus of this study was to explore the infuence of the alkaloid ricinine, found in the nectar of the castor bean Ricinus communis, on the ability of mosquitoes to transmit Plasmodium falciparum. Methods: Females of Anopheles gambiae and its sibling species Anopheles coluzzii were exposed to ricinine through sugar feeding assays to assess the efect of this phytochemical on mosquito survival, level of P. falciparum infection and growth rate of the parasite. Results: Ricinine induced a signifcant reduction in the longevity of both Anopheles species. Ricinine caused acceleration in the parasite growth rate with an earlier invasion of the salivary glands in both species. At a concentration of 0.04 g l −1 in An. coluzzii, ricinine had no efect on mosquito infection, while 0.08 g l −1 ricinine-5% glucose solution induced a 14% increase in An. gambiae infection rate. Conclusions: Overall, our fndings reveal that consumption of certain nectar phytochemicals can have unexpected and contrasting efects on key phenotypic traits that govern the intensity of malaria transmission. Further studies will be required before concluding on the putative role of ricinine as a novel control agent, including the development of ricinine-based toxic and transmission-blocking sugar baits. Testing other secondary phytochemicals in plant nectar will provide a broader understanding of the impact which plants can have on the transmission of vector-borne diseases.
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    Data-driven and interpretable machine-learning modeling to explore the fne-scale environmental determinants of malaria vectors biting rates in rural Burkina Faso
    (Parasites Vectors, 2021-06-29) Taconet, Paul; Porciani, Angélique; Soma, Dieudonné Diloma
    Background: Improving the knowledge and understanding of the environmental determinants of malaria vector abundance at fine spatiotemporal scales is essential to design locally tailored vector control intervention. This work is aimed at exploring the environmental tenets of human-biting activity in the main malaria vectors (Anopheles gambiae s.s., Anopheles coluzzii and Anopheles funestus) in the health district of Diébougou, rural Burkina Faso. Methods: Anopheles human-biting activity was monitored in 27 villages during 15 months (in 2017–2018), and environmental variables (meteorological and landscape) were extracted from high-resolution satellite imagery. A two-step data-driven modeling study was then carried out. Correlation coefficients between the biting rates of each vector species and the environmental variables taken at various temporal lags and spatial distances from the biting events were first calculated. Then, multivariate machine-learning models were generated and interpreted to (i) pinpoint primary and secondary environmental drivers of variation in the biting rates of each species and (ii) identify complex associations between the environmental conditions and the biting rates. Results: Meteorological and landscape variables were often significantly correlated with the vectors’ biting rates. Many nonlinear associations and thresholds were unveiled by the multivariate models, for both meteorological and landscape variables. From these results, several aspects of the bio-ecology of the main malaria vectors were identified or hypothesized for the Diébougou area, including breeding site typologies, development and survival rates in relation to weather, fight ranges from breeding sites and dispersal related to landscape openness. Conclusions: Using high-resolution data in an interpretable machine-learning modeling framework proved to be an efficient way to enhance the knowledge of the complex links between the environment and the malaria vectors at a local scale. More broadly, the emerging feld of interpretable machine learning has significant potential to help improve our understanding of the complex processes leading to malaria transmission, and to aid in developing