In an epidemic, individuals can widely differ in the way they spread the infection depending on their age or on the number of days they have been infected for. In the absence of pharmaceutical ...interventions such as a vaccine or treatment, non-pharmaceutical interventions (e.g. physical or social distancing) are essential to mitigate the pandemic. We develop an original approach to identify the optimal age-stratified control strategy to implement as a function of the time since the onset of the epidemic. This is based on a model with a double continuous structure in terms of host age and time since infection. By applying optimal control theory to this model, we identify a solution that minimizes deaths and costs associated with the implementation of the control strategy itself. We also implement this strategy for three countries with contrasted age distributions (Burkina-Faso, France, and Vietnam). Overall, the optimal strategy varies throughout the epidemic, with a more intense control early on, and depending on host age, with a stronger control for the older population, except in the scenario where the cost associated with the control is low. In the latter scenario, we find strong differences across countries because the control extends to the younger population for France and Vietnam 2 to 3 months after the onset of the epidemic, but not for Burkina Faso. Finally, we show that the optimal control strategy strongly outperforms a constant uniform control exerted over the whole population or over its younger fraction. This improved understanding of the effect of age-based control interventions opens new perspectives for the field, especially for age-based contact tracing.
Objective
To study the contribution of blood transfusion management in the improvement of maternal and perinatal outcomes in pregnant women with sickle cell disease in Ouagadougou.
Methods
A ...cross‐sectional retrospective study with data collected from February 2012 to January 2014 was used. Patients were differentiated into three groups: patients with at least one exchange transfusion, patients who received blood transfusion, and patients who did not receive any transfusion. Data were collected from patients’ patient care documents.
Results
One hundred and sixty‐four patients were included, of whom 53 were in the first group, 32 in the second group, and 79 in the third group. Maternal complications in the last trimester of pregnancy were significantly less important (P=0.000) in the first group (58.5%) than in the second (78.5%) and third group (91.1%). The same trend was observed for postpartum maternal mortality (5.7%; 12.5%; 12.6%; P=0.009). Fetal complications such as preterm birth and early neonatal death were lower in the first group (15.1%; 1.8%) than in the second (40.6%; 23.1%) and third group (32.9%; 7.6%).
Conclusion
Prophylactic blood transfusion is an important part of the management of pregnant patients with sickle cell disease.
Prophylactic blood transfusion is essential in the management of pregnant women with sickle cell disease. It is important that transfusion is targeted but not systematic.
Recently, we found that a new malaria vaccine, R21/Matrix-M, had over 75% efficacy against clinical malaria with seasonal administration in a phase 2b trial in Burkina Faso. Here, we report on safety ...and efficacy of the vaccine in a phase 3 trial enrolling over 4800 children across four countries followed for up to 18 months at seasonal sites and 12 months at standard sites.
We did a double-blind, randomised, phase 3 trial of the R21/Matrix-M malaria vaccine across five sites in four African countries with differing malaria transmission intensities and seasonality. Children (aged 5–36 months) were enrolled and randomly assigned (2:1) to receive 5 μg R21 plus 50 μg Matrix-M or a control vaccine (licensed rabies vaccine Abhayrab). Participants, their families, investigators, laboratory teams, and the local study team were masked to treatment. Vaccines were administered as three doses, 4 weeks apart, with a booster administered 12 months after the third dose. Half of the children were recruited at two sites with seasonal malaria transmission and the remainder at standard sites with perennial malaria transmission using age-based immunisation. The primary objective was protective efficacy of R21/Matrix-M from 14 days after third vaccination to 12 months after completion of the primary series at seasonal and standard sites separately as co-primary endpoints. Vaccine efficacy against multiple malaria episodes and severe malaria, as well as safety and immunogenicity, were also assessed. This trial is registered on ClinicalTrials.gov, NCT04704830, and is ongoing.
From April 26, 2021, to Jan 12, 2022, 5477 children consented to be screened, of whom 1705 were randomly assigned to control vaccine and 3434 to R21/Matrix-M; 4878 participants received the first dose of vaccine. 3103 participants in the R21/Matrix-M group and 1541 participants in the control group were included in the modified per-protocol analysis (2412 51·9% male and 2232 48·1% female). R21/Matrix-M vaccine was well tolerated, with injection site pain (301 18·6% of 1615 participants) and fever (754 46·7% of 1615 participants) as the most frequent adverse events. Number of adverse events of special interest and serious adverse events did not significantly differ between the vaccine groups. There were no treatment-related deaths. 12-month vaccine efficacy was 75% (95% CI 71–79; p<0·0001) at the seasonal sites and 68% (61–74; p<0·0001) at the standard sites for time to first clinical malaria episode. Similarly, vaccine efficacy against multiple clinical malaria episodes was 75% (71–78; p<0·0001) at the seasonal sites and 67% (59–73; p<0·0001) at standard sites. A modest reduction in vaccine efficacy was observed over the first 12 months of follow-up, of similar size at seasonal and standard sites. A rate reduction of 868 (95% CI 762–974) cases per 1000 children-years at seasonal sites and 296 (231–362) at standard sites occurred over 12 months. Vaccine-induced antibodies against the conserved central Asn-Ala-Asn-Pro (NANP) repeat sequence of circumsporozoite protein correlated with vaccine efficacy. Higher NANP-specific antibody titres were observed in the 5–17 month age group compared with 18–36 month age group, and the younger age group had the highest 12-month vaccine efficacy on time to first clinical malaria episode at seasonal (79% 95% CI 73–84; p<0·001) and standard (75% 65–83; p<0·001) sites.
R21/Matrix-M was well tolerated and offered high efficacy against clinical malaria in African children. This low-cost, high-efficacy vaccine is already licensed by several African countries, and recently received a WHO policy recommendation and prequalification, offering large-scale supply to help reduce the great burden of malaria in sub-Saharan Africa.
The Serum Institute of India, the Wellcome Trust, the UK National Institute for Health Research Oxford Biomedical Research Centre, and Open Philanthropy.
Reduction of natural vegetation cover in the savannah of West Africa constitutes a pressing environmental concern that may lead to soil degradation. With the aim to assess the degradation of natural ...vegetation in the savannah of Burkina Faso, this study combined NDVI trends and fractional Land Use/Cover Change (LULCC). Fractional LULCC maps, derived from the aggregation of a 30 m Landsat LULCC map (1999–2011) to 250 m resolution of MODIS, were used to assess natural vegetation conversions in the small-scale spatial patterns of savannah landscapes. Mann-Kendall's monotonic trend test was applied to 250 m MODIS NDVI time series (2000–2011) to assess modifications of natural vegetation cover. Finally, the Spearman's correlation was employed to determine the relationship of natural vegetation degradation with environmental factors. The study revealed a vast conversion of natural vegetation into agriculture (15.9%) and non-vegetated area (1.8%) between 1999 and 2011. Significant decreasing NDVI trends (p < .05) indicated negative modifications of natural vegetation (2000–2011 period) occurring along the protected areas borders and in fragmented landscapes characterized by disruption of continuity in natural vegetation. Spearman's correlation showed that accessibility, climatic and topographic conditions favored natural vegetation degradation. The results can enable the development of efficient land degradation policies.
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•The study area experienced vast conversion of natural vegetation into agriculture and non-vegetated area.•In the period 2000-2011 significant negative modifications affected natural vegetation cover.•Accessibility, climatic and topographic conditions favored natural vegetation degradation in the study area.
•Increases in food prices during the COVID-19 pandemic led to a significant rise in moderate or severe food insecurity.•The effect of increases in food prices persisted in the medium term.•The effect ...on food insecurity was significantly worse in rural areas compared to urban areas following the price shocks.•Households cope with the price shock through financial assistance from domestic family and remittances from abroad.
Global food prices rose substantially after the start of the COVID-19 pandemic. This paper examines the impact of rising food prices during the pandemic on food security in Burkina Faso. We aim to answer two primary questions. First, how do food price shocks affect household food insecurity? Second, what coping strategies do households adopt in response to these price shocks? Leveraging country-wide high-frequency longitudinal data, we employ household fixed effect models to examine the effects. In the absence of direct information on local food prices, we use household-reported price shocks to capture province-level price increases and show that the results are consistent with national-level price increases.
We find significant and immediate increases in food insecurity following the price shocks, and this effect persists for at least two months. The price shocks most acutely affected the poorest households. Furthermore, food insecurity increased more in rural areas than in urban areas. The higher proportion of poorer households in rural areas explains part of this difference. We find that households primarily cope with the shock by relying on increased assistance from relatives in Burkina Faso and abroad.
This study is the first to use panel data with household fixed effects to examine the repercussions of the rise in food prices during the pandemic on food insecurity in a developing country and to examine the coping mechanisms employed by households. Given that food prices are likely to remain high globally for an extended period, our findings carry implications for the broader developing world. Furthermore, given the disproportionate effect on the poorest and those living in rural areas, the findings highlight the need for policies to mitigate the negative impacts of the price shocks and enhance overall food security in countries like Burkina Faso.
Groundwater contaminated with geogenic arsenic (As) is frequently used as drinking water in Burkina Faso, despite adverse health effects. This study focused on testing low-cost filter systems based ...on zero-valent iron (ZVI), which have not yet been explored in West Africa for As removal. The active ZVI bed was constructed using small-sized iron nails, embedded between sand layers. Household filters were tested for nine months in a remote village relying on tube well water with As concentrations of 400–1350 μg/L. Daily filtered volumes were 40–60 L, with flow rates of ~10 L/h. In parallel, downscaled laboratory filter columns were run to find the best set-up for optimal As removal, with special attention given to the influence of input pH, flow rate and water/nail contact time. Arsenic removal efficiencies in the field were 60–80% in the first six months of operation. The laboratory experiments revealed that trapped air in the nail layer greatly lowered As removal due to preferential flow and decreased water/nail contact time. Measures taken to avoid trapped air led to a partial improvement in the field filters, but effluent As remained >50 μg/L. Similar structural modifications were however very successful in the laboratory columns, where As removal efficiencies were consistently >95% and effluent concentrations frequently <10 μg/L, despite inflow As >1000 μg/L. A constantly saturated nail bed and careful flow control is necessary for optimal As removal. Slow flow and longer pauses between filtrations are important for sufficient contact times and for transformation of brown amorphous Fe-hydroxides to dense magnetite with incorporated As(V). This preliminary study has shown that nail-based filters have the potential to achieve As removal >90% in a field context if conditions (filter bed saturation, flow rate, pauses between filtrations) are well controlled.
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•Low-cost filters with nails as the active ZVI layer tested in field and laboratory.•Filters and columns operated with groundwater containing 500–1350 μg As/L.•Ensure permanently saturated nail bed to increase water/nail contact time.•Transformation of amorphous Fe-(hydr)oxides to stable magnetite with incorporated As(V)•Field filters achieved 60–80% As removal, lab columns >95%.
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•Chemistry of pyrite and arsenopyrite from the Mana gold deposits.•Four hydrothermal fluid events identified with 2 source reservoirs over ∼150 Ma.•Early magmatic and metamorphic ...fluid events as olds as ∼2172 Ma.•Regional Au-As metamorphic fluid events during D3MD and D4MD with late gold remobilization.•Geochemical diagram using As, Ag, Sb, Bi for separating the pyrite origin in orogenic gold deposit.
Mana is a world-class Paleoproterozoic orogenic gold district (∼8.0 Moz) that includes five gold deposits (Fofina, Nyafé, Siou, Wona-Kona and Yaho) hosted in various rocks in the northern part of the Birimian Houndé greenstone belt, western Burkina Faso. The gold deposits recorded different styles of mineralization associated with sulfides during polyphase deformation events. Detailed petrographic and LA-ICP-MS analyses of pyrites and arsenopyrites from the main mineralization of each deposit provide new information on the potential gold and arsenic sources and timing of fluids responsible for mineralization at Mana. Four hydrothermal fluid events associated with two distinct source reservoirs and at least two hydrothermal systems were recognized. The first hydrothermal fluid event was generated during the Eoeburnean D1MD (MD for Mana district) shortening event (∼2172 Ma), evidence of which is preserved in the Fofina and Siou deposits, and occurred under greenschist metamorphic facies conditions. Economic gold deposits at Fofina are associated with metamorphic disseminated pyrite (Py1F) in black shale, zoned pyrite (Py2F) enriched in As, Ni, Cu, Ag, Sb, W, Au and Pb, and arsenopyrite in folded V1F quartz-carbonate veins. In contrast, the Siou deposit exhibits Au in porous pyrite cores (Py1S), which are associated with Ag, Bi, Te and W (±Sb) in V1S quartz veins hosted in the Siou granodiorite. These two trace element suites are interpreted as having been induced by a metamorphic source in the Fofina deposit and by a local contribution of a magmatic source in the Siou deposit. The second hydrothermal fluid event occurred during the Eburnean D3MD transpressional event (2113–2090 Ma) in the Nyafé deposit. This event is defined by Au-As-rich rims in hydrothermal pyrite (Py3N) and by the co-precipitation of Au-rich arsenopyrite in the V3N quartz veinlets (V3N) controlled by a second-order dextral shear zone. The third and main hydrothermal fluid event during the D4MD transpressional event (∼2090 Ma) is characterized by the development of strong silicification and by zoned pyrites (Py3WK and Py2Y) and Au-rich arsenopyrite in the Wona-Kona and Yaho deposits. However, the same late Au-As-rich rims in hydrothermal pyrite are observed in both deposits and in the Nyafé deposit, and these rims are interpreted to be related to the same economic gold source related to the Lower Birimian metamorphic reservoir, composed of black shale (diagenetic framboidal pyrite) and tholeiitic basalts. The diagenetic framboidal Py1WK in black shale (Lower Birimian group) is enriched in Au (median of 0.8 ppm), low in As (median of 70 ppm), with other trace elements (Ni, Cu, Zn, Ag, Sb and Pb). The last hydrothermal event is associated with free gold remobilization in late microfractures in the Wona-Kona and Siou deposit during the reactivation of major transcurrent shear zones during the D4MD event or the D5MD shortening event (as late as 2022 Ma). A binary diagram of As/Ag vs. Sb/Bi appears to be effective at separating the diagenetic, magmatic and metamorphic pyrites and could be used in orogenic gold exploration to ascertain potential gold endowment at the district scale.
Introduction: The TP53 and CHEK2 genes have been described as breast cancer susceptibility genes and some of their polymorphisms have been associated with an increased risk of breast cancer in ...certain populations.Aim: The objective of this study was to investigate the p.R72P and PIN3 Ins16bp (TP53) polymorphisms and the I157T (CHEK2) mutation developping of breast cancer. Methods: This case-control study had enrolled 144 participants including 65 cases (breast cancer patients) and 79 controls (women without breast abnormalities) in the city of Ouagadougou in Burkina Faso. The DNA was extracted using the method of “salting out” and the genotyping of polymorphisms was performed by ASO-PCR (Allele Specific Oligonucleotides - Polymerase Chain Reaction), conventional PCR and PCR-RFLP (Polymerase Chain Reaction - Restriction Fragment Length Polymorphism) techniques. Results: The heterozygous genotype (RP) of the p.R72P polymorphism of TP53 gene was in the majority in cases (73.85%) and controls (73.42%). Regarding to the PIN3 Ins16bp polymorphism of TP53 gene, the homozygous wild type (A1A1) was the most represented in both cases (53.85%) and controls (60.76%). Concerning the I157T mutation of CHEK2 gene, only one (01) patient was homozygous mutant (TT) and no controls had the mutation. This study found no association between these polymorphisms and the risk of breast cancer occurrence (p.R72P (OR=0.96; 95%IC (0.59-1.56); p=0.471), PIN3 Ins16bp (OR= 1.1; 95%IC (0.61-1.98); p=0.420)). Conclusion: This study showed that the P allele of the p.R72P polymorphism and the wild-type allele (A1) of the PIN3 Ins16bp polymorphism were in the majority. The I157T mutation was very rare. These polymorphisms were not associated with the risk of developing breast cancer in this study.
INTRODUCTION: Les faibles niveaux d’utilisation des contraceptifs en Afrique de l´Ouest sont responsables de taux de fécondité élevés, ce qui limite le développement économique. Le coût des ...contraceptifs modernes étant une contrainte importante, le gouvernement du Burkina Faso a décidé de rendre la planification familiale gratuite. Avant cette nouvelle politique, nous avons fourni aux femmes rurales un bon qui leur donnait un accès gratuit aux contraceptifs modernes. L´analyse des déterminants de l´utilisation du bon fournit des informations pertinentes pour le potentiel de la nouvelle politique gouvernementale.
Seeds of three Okra local genotypes of Burkina Faso, UAE22, KBG535 and KBG24, were irradiated with gamma rays at doses ranging from 200 to 3000 Gy using 60Co sources at IBD-CETT, in Burkina Faso. ...Seeds germination was evaluated in laboratory and then some were sown and plants maintained at two per pot. Traits were measured from germination to fruits maturity. Germination rate below 50% was observed at doses of 400 Gy and from 600 to 800 Gy for UAE22, andat 1600 Gy for KBG535. Up to 3000 Gy, seeds’ germination rate was still above 20%. The survival rate at 60 DAS reached 0% at doses of 1400, 1600 and 2000 Gy respectively for KBG535, KBG24 and UAE22. Also, at doses below 600 Gy, time to budding and flowering was reduced for the 3 genotypes. UAE22 did not show any increase for fruit characteristics, except the number of fruits per plant from 200 to 800 Gy. KBG24 and KBG535 showed increases of fruit traits at some doses between 200 and 800 Gy. As for seeds traits, the dose of 200 Gy had an increasing effect for KBG535 and that of 400 Gy had the same effect for UAE22 and KBG24, except the weight of seeds per plant. All the traits studied showed significant variation depending on doses and also genotypes. Irradiation of okra seeds was therefore an appreciable source of induction of variation in quantitative traits.
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