Variabilité pluviométrique et développement de l’activité agricole dans la région de Kolda (Sénégal)

L’agriculture familiale s’affiche indéniablement comme un pilier de la sécurité alimentaire nationale sénégalaise. Elle représente près de 80 % des exploitations en Afrique sub-saharienne et emploie 75 % des actifs. Elle se caractérise par l’importance des cultures pluviales (96 % des plantes cultivées), témoignant ainsi de sa dépendance à la pluviométrie saisonnière. Or, le climat est sujet à une variabilité interannuelle et certains parlent même de changement climatique. Cette étude analyse la variabilité pluviométrique et permet d’identifier les stratégies d’adaptation mises en œuvre pour tenter de maintenir un niveau de production permettant de satisfaire les besoins alimentaires des populations. L’étude s’appuie sur le traitement de données agro-climatiques, sur des travaux de terrain (enquêtes et entretien) et sur des tests de corrélation (nuage de points et Analyse en Composantes Principales). Les résultats l’ACP révèlent que l’influence de la pluviométrie sur la variation des productions est faible, car le R2 (pluviométrie et rendements agricoles) est inférieur à 0,1. Globalement, l’analyse comparative entre les deux périodes de références (1951-1980 et 1981-2010) révèle un raccourcissement de la durée de la saison des pluies à la station de Kolda. Des stratégies telles que l’adoption de variétés à cycle court, le recalage du calendrier cultural selon le contexte climatique en vigueur ont été identifiées.Family farming is undeniably a pillar of Senegalese national food security. It accounts for nearly 80% of farms in sub-Saharan Africa and employs 75% of the workforce. It is characterized by the importance of rain fed crops (96% of cultivated plants), thus testifying to its dependence on seasonal rainfall. However, climate is subject to inter-annual variability and some even talk about climate change. This study analyses rainfall variability and identifies adaptation strategies implemented to try to maintain a level of production that allows them to meet their food needs. The study is based on agro-climatic data processing, fieldwork (surveys and maintenance) and Principal Component Analysis (PCA). The results show that rainfall was in surplus from 1951 to 1970, in deficit from 1971 to 1990 and irregular (alternating between dry and wet years) from 1991 to the present. As for exits from the ACP, it turns out that rainfall is not the only factor responsible for the variation in production. Strategies such as the adoption of short-cycle varieties, the recalculation of the crop calendar according to the current climate context have been identified

Robust stabilization of the current profile in tokamak plasmas using sliding mode approach in infinite dimension

International audienceThis paper deals with the robust stabilization of the spatial distribution of tokamak plasmas current profile using a sliding mode feedback control approach. The control design is based on the 1D resistive diffusion equation of the magnetic flux that governs the plasma current profile evolution. The feedback control law is derived in the infinite dimensional setting without spatial discretization. Numerical simulations are provided and the tuning of the controller parameters that would reject uncertain perturbations is discussed. Closed loop simulations performed on realistic test cases using aphysics based tokamak integrated simulator confirm the relevance of the proposed control algorithm in view of practical implementation

Qualitative study to develop processes and tools for the assessment and tracking of African institutions’ capacity for operational health research

Objectives Research is key to achieving global development goals. Our objectives were to develop and test an evidence-informed process for assessing health research management and support systems (RMSS) in four African universities and for tracking interventions to address capacity gaps. Setting Four African universities. Participants 83 university staff and students from 11 cadres. Intervention/methods A literature-informed ‘benchmark’ was developed and used to itemise all components of a university’s health RMSS. Data on all components were collected during site visits to four African universities using interview guides, document reviews and facilities observation guides. Gaps in RMSS capacity were identified against the benchmark and institutional action plans developed to remedy gaps. Progress against indicators was tracked over 15 months and common challenges and successes identified. Results Common gaps in operational health research capacity included no accessible research strategy, a lack of research e-tracking capability and inadequate quality checks for proposal submissions and contracts. Feedback indicated that the capacity assessment was comprehensive and generated practical actions, several of which were no-cost. Regular follow-up helped to maintain focus on activities to strengthen health research capacity in the face of challenges. Conclusions Identification of each institutions’ strengths and weaknesses against an evidence-informed benchmark enabled them to identify gaps in in their operational health research systems, to develop prioritised action plans, to justify resource requests to fulfil the plans and to track progress in strengthening RMSS. Use of a standard benchmark, approach and tools enabled comparisons across institutions which has accelerated production of evidence about the science of research capacity strengthening. The tools could be used by institutions seeking to understand their strengths and to address gaps in research capacity. Research capacity gaps that were common to several institutions could be a ‘smart’ investment for governments and health research funders

Qualitative study to develop processes and tools for the assessment and tracking of African institutions’ capacity for operational health research

Objectives Research is key to achieving global development goals. Our objectives were to develop and test an evidence-informed process for assessing health research management and support systems (RMSS) in four African universities and for tracking interventions to address capacity gaps. Setting Four African universities. Participants 83 university staff and students from 11 cadres. Intervention/methods A literature-informed ‘benchmark’ was developed and used to itemise all components of a university’s health RMSS. Data on all components were collected during site visits to four African universities using interview guides, document reviews and facilities observation guides. Gaps in RMSS capacity were identified against the benchmark and institutional action plans developed to remedy gaps. Progress against indicators was tracked over 15 months and common challenges and successes identified. Results Common gaps in operational health research capacity included no accessible research strategy, a lack of research e-tracking capability and inadequate quality checks for proposal submissions and contracts. Feedback indicated that the capacity assessment was comprehensive and generated practical actions, several of which were no-cost. Regular follow-up helped to maintain focus on activities to strengthen health research capacity in the face of challenges. Conclusions Identification of each institutions’ strengths and weaknesses against an evidence-informed benchmark enabled them to identify gaps in in their operational health research systems, to develop prioritised action plans, to justify resource requests to fulfil the plans and to track progress in strengthening RMSS. Use of a standard benchmark, approach and tools enabled comparisons across institutions which has accelerated production of evidence about the science of research capacity strengthening. The tools could be used by institutions seeking to understand their strengths and to address gaps in research capacity. Research capacity gaps that were common to several institutions could be a ‘smart’ investment for governments and health research funders

Treatment of asymptomatic carriers with artemether-lumefantrine: an opportunity to reduce the burden of malaria?

Background: Increased investment and commitment to malaria prevention and treatment strategies across Africa has produced impressive reductions in the incidence of this disease. Nevertheless, it is clear that further interventions will be necessary to meet the international target of a reversal in the incidence of malaria by 2015. This article discusses the prospective role of an innovative malaria control strategy - the community-based treatment of asymptomatic carriers of Plasmodium falciparum, with artemisinin-based combination therapy (ACT). The potential of this intervention was considered by key scientists in the field at an Advisory Board meeting held in Basel, in April 2009. This article summarizes the discussions that took place among the participants. Presentation of the hypothesis: Asymptomatic carriers do not seek treatment for their infection and, therefore, constitute a reservoir of parasites and thus a real public-health risk. The systematic identification and treatment of individuals with asymptomatic P. falciparum as part of a surveillance intervention strategy should reduce the parasite reservoir, and if this pool is greatly reduced, it will impact disease transmission. Testing the hypothesis: This article considers the populations that could benefit from such a strategy and examines the ethical issues associated with the treatment of apparently healthy individuals, who represent a neglected public health risk. The potential for the treatment of asymptomatic carriers to impair the development of protective immunity, resulting in a \u27rebound\u27 and age escalation of malaria incidence, is also discussed. For policymakers to consider the treatment of asymptomatic carriers with ACT as a new tool in their malaria control programmes, it will be important to demonstrate that such a strategy can produce significant benefits, without having a negative impact on the efficacy of ACT and the health of the target population. Implications of the hypothesis: The treatment of asymptomatic carriers with ACT is an innovative and essential tool for breaking the cycle of infection in some transmission settings. Safe and effective medicines can save the lives of children, but the reprieve is only temporary so long as the mosquitoes can become re-infected from the asymptomatic carriers. With improvements in rapid diagnostic tests that allow easier identification of asymptomatic carriers, the elimination of the pool of parasites is within reach. © 2010 Ogutu et al; licensee BioMed Central Ltd

Application of geographically-weighted regression analysis to assess risk factors for malaria hotspots in Keur Soce health and demographic surveillance site.

BACKGROUND: In Senegal, considerable efforts have been made to reduce malaria morbidity and mortality during the last decade. This resulted in a marked decrease of malaria cases. With the decline of malaria cases, transmission has become sparse in most Senegalese health districts. This study investigated malaria hotspots in Keur Soce sites by using geographically-weighted regression. Because of the occurrence of hotspots, spatial modelling of malaria cases could have a considerable effect in disease surveillance. METHODS: This study explored and analysed the spatial relationships between malaria occurrence and socio-economic and environmental factors in small communities in Keur Soce, Senegal, using 6 months passive surveillance. Geographically-weighted regression was used to explore the spatial variability of relationships between malaria incidence or persistence and the selected socio-economic, and human predictors. A model comparison of between ordinary least square and geographically-weighted regression was also explored. Vector dataset (spatial) of the study area by village levels and statistical data (non-spatial) on malaria confirmed cases, socio-economic status (bed net use), population data (size of the household) and environmental factors (temperature, rain fall) were used in this exploratory analysis. ArcMap 10.2 and Stata 11 were used to perform malaria hotspots analysis. RESULTS: From Jun to December, a total of 408 confirmed malaria cases were notified. The explanatory variables-household size, housing materials, sleeping rooms, sheep and distance to breeding site returned significant t values of -0.25, 2.3, 4.39, 1.25 and 2.36, respectively. The OLS global model revealed that it explained about 70 % (adjusted R(2) = 0.70) of the variation in malaria occurrence with AIC = 756.23. The geographically-weighted regression of malaria hotspots resulted in coefficient intercept ranging from 1.89 to 6.22 with a median of 3.5. Large positive values are distributed mainly in the southeast of the district where hotspots are more accurate while low values are mainly found in the centre and in the north. CONCLUSION: Geographically-weighted regression and OLS showed important risks factors of malaria hotspots in Keur Soce. The outputs of such models can be a useful tool to understand occurrence of malaria hotspots in Senegal. An understanding of geographical variation and determination of the core areas of the disease may provide an explanation regarding possible proximal and distal contributors to malaria elimination in Senegal

Randomized Trial of Piperaquine with Sulfadoxine-Pyrimethamine or Dihydroartemisinin for Malaria Intermittent Preventive Treatment in Children

BACKGROUND: The long terminal half life of piperaquine makes it suitable for intermittent preventive treatment for malaria but no studies of its use for prevention have been done in Africa. We did a cluster randomized trial to determine whether piperaquine in combination with either dihydroartemisin (DHA) or sulfadoxine-pyrimethamine (SP) is as effective, and better tolerated, than SP plus amodiaquine (AQ), when used for intermittent preventive treatment in children delivered by community health workers in a rural area of Senegal. METHODS: Treatments were delivered to children 3-59 months of age in their homes once per month during the transmission season by community health workers. 33 health workers, each covering about 60 children, were randomized to deliver either SP+AQ, DHA+PQ or SP+PQ. Primary endpoints were the incidence of attacks of clinical malaria, and the incidence of adverse events. RESULTS: 1893 children were enrolled. Coverage of monthly rounds and compliance with daily doses was similar in all groups; 90% of children received at least 2 monthly doses. Piperaquine combinations were better tolerated than SP+AQ with a significantly lower risk of common, mild adverse events. 103 episodes of clinical malaria were recorded during the course of the trial. 68 children had malaria with parasitaemia >3000/microL, 29/671 (4.3%) in the SP+AQ group, compared with 22/604 (3.6%) in the DHA+PQ group (risk difference 0.47%, 95%CI -2.3%,+3.3%), and 17/618 (2.8%) in the SP+PQ group (risk difference 1.2%, 95%CI -1.3%,+3.6%). Prevalences of parasitaemia and the proportion of children carrying Pfdhfr and Pfdhps mutations associated with resistance to SP were very low in all groups at the end of the transmission season. CONCLUSIONS: Seasonal IPT with SP+PQ in children is highly effective and well tolerated; the combination of two long-acting drugs is likely to impede the emergence of resistant parasites. TRIAL REGISTRATION: ClinicalTrials.gov NCT00529620

Choriocarcinoma on hysterectomy specimen in Senegal: histological study

Background: Trophoblastic diseases are in general exclusive to women in their reproductive years. Gestational choriocarcinoma (GC) is a rare malignant tumor derived from the trophoblast of women in childbearing age. Our objective was to study the epidemiological and clinicopathologic aspects at the laboratories of pathological anatomy and cytology (ACP) of Aristide Le Dantec Hospital and General Idrissa Pouye Hospital.Methods: Our study was conducted in the anatomy and pathology laboratories of the Hôpital Général Idrissa Pouye and the Hôpital Aristide Le Dantec in Dakar. This study was based on records of pathological reports of gestational choriocarcinomas from these different laboratories. This was a retrospective and descriptive bi-centric study, spread over eight (8) years from January 1, 2013, to December 31, 2020. All cases diagnosed on hysterectomy specimens and with a formal conclusion of choriocarcinoma have been included. We recorded the data collected in Excel 2007 software and the analysis was made using Epi Info.Results: We collected 25 cases of choriocarcinomas. The mean age of the patients was 38.1±9.7. Mixed seat tumors (intra-cavitary and intra-mural) were the most frequent with 48% of cases. Patients who were at FIGO stage 1 represented for 88% of cases.Conclusions: Gestational choriocarcinoma (GC) is a proliferation of the trophoblast (cytotrophoblast and syncitiotrophoblast). This study has helped establish histopathological data of choriocarcinoma on hysterectomy specimen in Dakar