20 research outputs found

    The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

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    INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

    Towards a multi-use participatory management strategy for water resources in the Senegal River Delta : decision-making process and regulation tools around Lake Guiers.

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    L’objet de la thĂšse est d’évaluer la pertinence de l’approche participative comme outil-levier pour une gestion locale mieux partagĂ©e et durable des ressources en eau autour du lac de Guiers au SĂ©nĂ©gal. Unique lac d’eau douce d’importance du pays, implantĂ© dans une zone semi-dĂ©sertique de la rĂ©gion Ă©cologique sahĂ©lienne, le lac de Guiers est trĂšs convoitĂ© par plusieurs types d’usages. Il est considĂ©rĂ©, au plan national comme au plan local, comme une source vitale d’approvisionnement en eau potable des rĂ©gions proches et de grandes villes une ressource stratĂ©gique pour le maintien de l’autosuffisance alimentaire ainsi qu’un moteur de dĂ©veloppement Ă©conomique pour les communautĂ©s villageoises agro-pastorales. La dĂ©marche mĂ©thodologique retenue est de type « bottom-up », partant du diagnostic de terrain du cas du lac de Guiers. Elle s’appuie sur des entretiens et enquĂȘtes par questionnaires auprĂšs des gestionnaires et des usagers de l’eau du lac, une analyse des jeux d’acteurs dans un cadre institutionnel en Ă©volution et l’analyse des dynamiques spatiales de rĂ©partition des usages de l’eau. Ce diagnostic montre dans quelle mesure l’approche participative prĂŽnĂ©e dans les stratĂ©gies et plans de gestion de l’eau du lac de Guiers est effectivement mise en Ɠuvre et vient renforcer la participation des usagers de la ressource en eau pour parvenir Ă  une gestion mieux partagĂ©e et durable de celle-ci. L’approche participative n'est fonctionnelle que si le cadre de gestion s’inscrit dans une dĂ©marche globale de gestion concertĂ©e et intĂ©grĂ©e dans laquelle tous les usagers et les acteurs gestionnaires sont co-gestionnaires de la dĂ©marche.De plus, l’approche participative reste souvent difficile Ă  organiser. Cette difficultĂ© est d’autant plus forte que l’étendue gĂ©ographique est grande, et qu’il s’agit de faire participer tous les usagers et acteurs gestionnaires concernĂ©s Ă  toutes les Ă©chelles avec des intĂ©rĂȘts parfois contradictoires. Par ailleurs, la thĂšse rĂ©vĂšle que l’accroissement de l’implantation d’activitĂ©s Ă©conomiques sensĂ©es profiter Ă  la rĂ©gion conduit Ă  des effets pervers qui vont Ă  l’encontre des objectifs des plans de gestion : baisse de la qualitĂ© de l’eau et des quantitĂ©s disponibles (pollution causĂ©e par les rejets des agro-industries et augmentation des volumes de prĂ©lĂšvement).Toutes les sĂ©ries d’actions engagĂ©es constituent des dĂ©penses pour les acteurs gestionnaires (maintenance des infrastructures, contrĂŽle des prĂ©lĂšvements, lutte contre la pollution etc.). Dans ce domaine, la thĂšse recommande que la gestion de la ressource en eau du lac prenne en compte cette dimension dĂ©terminante, en dĂ©veloppant de nouveaux outils de gestion correspondant Ă  la valorisation Ă©conomique de l’eau et en crĂ©ant un Observatoire, outil intĂ©grateur de son avenir durable. Ceci est une condition sine qua non pour une amĂ©lioration des conditions de vie des riverains. La thĂšse confirme, Ă  travers le cas du lac de Guiers, la pertinence des thĂ©ories de l’approche participative pour accompagner et aider ses acteurs gestionnaires dans leur apprĂ©hension et leur organisation du systĂšme de gestion.The aim of the thesis is to evaluate the relevance of the participatory approach as a leverage tool to achieve a better shared and sustainable local management of water resources around lake Guiers in Senegal. It is the only freshwater lake of importance in the country. Located in a semi-desert zone of the Sahelian ecological region, lake Guiers is coveted by several types of uses. It is considered both nationally and locally as a vital resource for drinking water supply in nearby regions and large cities as a strategic resource for maintaining food self-sufficiency, as well as being a vector of economic development of the agro-pastoral village communities.The methodological approach adopted is the "bottom-up" approach, starting from field diagnosis of the case of lake Guiers. It is based on interviews and questionnaire surveys with managers and users of the lake’s water, an analysis of the sets of actors in an evolving institutional framework and the analysis of the spatial dynamics of distribution of the uses of the lake’s water. This diagnosis demonstrates the extent to which the participatory approach advocated in the water management strategies and plans of lake Guiers is effectively implemented and strengthens the participation of water resource users in order to achieve a better shared and sustainable management of this water resource.The participatory approach is functional only if the management framework is part of a comprehensive, collaborative and integrated management approach in which all users and managers are involved in the decision-making process (co-management). Furthermore, the participatory approach is often difficult to organize. This difficulty increases when the geographical scope is large and the aim is to involve all the users and managers concerned at all levels with sometimes contradictory interests. Moreover, the thesis reveals that the increase in the implantation of economic activities that are supposed to benefit the region leads to perverse effects that run counter to the objectives of the management plans: a drop in water quality and of the available quantities (pollution caused by discharges from agro-industries and increased collection volumes). All the series of actions (services) involved imply expenditures for the management actors (maintenance of infrastructures, control of sampling, pollution control etc.). In this area, the thesis recommends that the management of water resources in the lake should take into account this decisive dimension, by developing new management tools corresponding to the economic valuation of water and by creating an observatory, an integrating tool of its sustainable future. This is a sine qua non condition for improving the living conditions of local residents. The thesis confirms, through the case of Lake Guiers, the relevance of the theories of the participatory approach to accompany and help its management actors in their apprehension and organization of the management system

    Vers une stratégie de gestion participative multi-usages de la ressource en eau dans le delta du fleuve Sénégal : processus de décision et outils de régulation autour du lac de Guiers

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    The aim of the thesis is to evaluate the relevance of the participatory approach as a leverage tool to achieve a better shared and sustainable local management of water resources around lake Guiers in Senegal. It is the only freshwater lake of importance in the country. Located in a semi-desert zone of the Sahelian ecological region, lake Guiers is coveted by several types of uses. It is considered both nationally and locally as a vital resource for drinking water supply in nearby regions and large cities as a strategic resource for maintaining food self-sufficiency, as well as being a vector of economic development of the agro-pastoral village communities.The methodological approach adopted is the "bottom-up" approach, starting from field diagnosis of the case of lake Guiers. It is based on interviews and questionnaire surveys with managers and users of the lake’s water, an analysis of the sets of actors in an evolving institutional framework and the analysis of the spatial dynamics of distribution of the uses of the lake’s water. This diagnosis demonstrates the extent to which the participatory approach advocated in the water management strategies and plans of lake Guiers is effectively implemented and strengthens the participation of water resource users in order to achieve a better shared and sustainable management of this water resource.The participatory approach is functional only if the management framework is part of a comprehensive, collaborative and integrated management approach in which all users and managers are involved in the decision-making process (co-management). Furthermore, the participatory approach is often difficult to organize. This difficulty increases when the geographical scope is large and the aim is to involve all the users and managers concerned at all levels with sometimes contradictory interests. Moreover, the thesis reveals that the increase in the implantation of economic activities that are supposed to benefit the region leads to perverse effects that run counter to the objectives of the management plans: a drop in water quality and of the available quantities (pollution caused by discharges from agro-industries and increased collection volumes). All the series of actions (services) involved imply expenditures for the management actors (maintenance of infrastructures, control of sampling, pollution control etc.). In this area, the thesis recommends that the management of water resources in the lake should take into account this decisive dimension, by developing new management tools corresponding to the economic valuation of water and by creating an observatory, an integrating tool of its sustainable future. This is a sine qua non condition for improving the living conditions of local residents. The thesis confirms, through the case of Lake Guiers, the relevance of the theories of the participatory approach to accompany and help its management actors in their apprehension and organization of the management system.L’objet de la thĂšse est d’évaluer la pertinence de l’approche participative comme outil-levier pour une gestion locale mieux partagĂ©e et durable des ressources en eau autour du lac de Guiers au SĂ©nĂ©gal. Unique lac d’eau douce d’importance du pays, implantĂ© dans une zone semi-dĂ©sertique de la rĂ©gion Ă©cologique sahĂ©lienne, le lac de Guiers est trĂšs convoitĂ© par plusieurs types d’usages. Il est considĂ©rĂ©, au plan national comme au plan local, comme une source vitale d’approvisionnement en eau potable des rĂ©gions proches et de grandes villes une ressource stratĂ©gique pour le maintien de l’autosuffisance alimentaire ainsi qu’un moteur de dĂ©veloppement Ă©conomique pour les communautĂ©s villageoises agro-pastorales. La dĂ©marche mĂ©thodologique retenue est de type « bottom-up », partant du diagnostic de terrain du cas du lac de Guiers. Elle s’appuie sur des entretiens et enquĂȘtes par questionnaires auprĂšs des gestionnaires et des usagers de l’eau du lac, une analyse des jeux d’acteurs dans un cadre institutionnel en Ă©volution et l’analyse des dynamiques spatiales de rĂ©partition des usages de l’eau. Ce diagnostic montre dans quelle mesure l’approche participative prĂŽnĂ©e dans les stratĂ©gies et plans de gestion de l’eau du lac de Guiers est effectivement mise en Ɠuvre et vient renforcer la participation des usagers de la ressource en eau pour parvenir Ă  une gestion mieux partagĂ©e et durable de celle-ci. L’approche participative n'est fonctionnelle que si le cadre de gestion s’inscrit dans une dĂ©marche globale de gestion concertĂ©e et intĂ©grĂ©e dans laquelle tous les usagers et les acteurs gestionnaires sont co-gestionnaires de la dĂ©marche.De plus, l’approche participative reste souvent difficile Ă  organiser. Cette difficultĂ© est d’autant plus forte que l’étendue gĂ©ographique est grande, et qu’il s’agit de faire participer tous les usagers et acteurs gestionnaires concernĂ©s Ă  toutes les Ă©chelles avec des intĂ©rĂȘts parfois contradictoires. Par ailleurs, la thĂšse rĂ©vĂšle que l’accroissement de l’implantation d’activitĂ©s Ă©conomiques sensĂ©es profiter Ă  la rĂ©gion conduit Ă  des effets pervers qui vont Ă  l’encontre des objectifs des plans de gestion : baisse de la qualitĂ© de l’eau et des quantitĂ©s disponibles (pollution causĂ©e par les rejets des agro-industries et augmentation des volumes de prĂ©lĂšvement).Toutes les sĂ©ries d’actions engagĂ©es constituent des dĂ©penses pour les acteurs gestionnaires (maintenance des infrastructures, contrĂŽle des prĂ©lĂšvements, lutte contre la pollution etc.). Dans ce domaine, la thĂšse recommande que la gestion de la ressource en eau du lac prenne en compte cette dimension dĂ©terminante, en dĂ©veloppant de nouveaux outils de gestion correspondant Ă  la valorisation Ă©conomique de l’eau et en crĂ©ant un Observatoire, outil intĂ©grateur de son avenir durable. Ceci est une condition sine qua non pour une amĂ©lioration des conditions de vie des riverains. La thĂšse confirme, Ă  travers le cas du lac de Guiers, la pertinence des thĂ©ories de l’approche participative pour accompagner et aider ses acteurs gestionnaires dans leur apprĂ©hension et leur organisation du systĂšme de gestion

    Benthic Fauna Assessment along the Navigation Channel from the Mouth of the Casamance Estuary to Ziguinchor City

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    This study aimed at studying the benthic fauna of the Casamance estuary (Senegal) through the analysis of its composition at 13 stations located along the channel from the estuary mouth to Ziguinchor port (estuary upstream), which may provide indications of the potential environmental impact of the navigation channel dredged on the estuary. Sixty taxa distributed in twelve phyla were identified, of which the most abundant were bivalve mollusks, annelids, and nematodes. The species abundance and species richness varied from five (estuary mouth) to thirty species (upstream). Correspondence factorial analysis (CFA) and factor analysis for mixed data (FAMD) showed, respectively, that 34% (Dim 1 = 15.6% and Dim 2 = 18.4%) and 35.5% (Dim 1 = 20.8% and Dim 2 = 14.7%) of total inertia was explained by the first two axes and a significant correlation between the dominant species distribution, sediment type, and depth of the sampled station. Overall, Spearman’s rank correlation indicated a significant negative correlation of the species abundance and species richness with distance from the estuary mouth. From these results, it appears that sediment type, depth of the sampled stations, salinity, and the mangrove forests are key factors that influence the distribution and abundance of benthic fauna in the Casamance estuary. The monitoring plans for the preservation of the health and biological diversity of this ecosystem, especially benthic fauna biodiversity, should take into consideration the seasonal variations of rainfalls and related changes in terms of physicochemical factors. This should include evaluating the long-term responses of benthic organisms to dredging activities, boat traffic, and especially physical habitat modifications, changes in migration ways, and pollution pressure

    Benthic Fauna Assessment along the Navigation Channel from the Mouth of the Casamance Estuary to Ziguinchor City

    No full text
    This study aimed at studying the benthic fauna of the Casamance estuary (Senegal) through the analysis of its composition at 13 stations located along the channel from the estuary mouth to Ziguinchor port (estuary upstream), which may provide indications of the potential environmental impact of the navigation channel dredged on the estuary. Sixty taxa distributed in twelve phyla were identified, of which the most abundant were bivalve mollusks, annelids, and nematodes. The species abundance and species richness varied from five (estuary mouth) to thirty species (upstream). Correspondence factorial analysis (CFA) and factor analysis for mixed data (FAMD) showed, respectively, that 34% (Dim 1 = 15.6% and Dim 2 = 18.4%) and 35.5% (Dim 1 = 20.8% and Dim 2 = 14.7%) of total inertia was explained by the first two axes and a significant correlation between the dominant species distribution, sediment type, and depth of the sampled station. Overall, Spearman’s rank correlation indicated a significant negative correlation of the species abundance and species richness with distance from the estuary mouth. From these results, it appears that sediment type, depth of the sampled stations, salinity, and the mangrove forests are key factors that influence the distribution and abundance of benthic fauna in the Casamance estuary. The monitoring plans for the preservation of the health and biological diversity of this ecosystem, especially benthic fauna biodiversity, should take into consideration the seasonal variations of rainfalls and related changes in terms of physicochemical factors. This should include evaluating the long-term responses of benthic organisms to dredging activities, boat traffic, and especially physical habitat modifications, changes in migration ways, and pollution pressure

    Length-based assessment of five small pelagic fishes in the Senegalese artisanal fisheries.

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    Fisheries management is an important strategy for ensuring sustainable use of resources. However, in West Africa, in the absence of quality data for many stocks and effective stock assessment models, the cases where this has been truly successful are notable for their rarity. In West Africa, small pelagic fish are of great socio-economic importance, as well as good indicators of fish stressors. Here, historical data (2004-2019) of five small pelagic species (Sardina pilchardus, Ethmalosa fimbriata, Trachurus trecae, Scomber colias and Mugil cephalus) were collected in Senegalese waters. The B/BMSY results showed stocks to be collapsed (B/BMSY = 0.13 and 0.1 for M. cephalus and S. pilchardus, respectively) and heavily overfished (B/BMSY = 0.24; E. fimbriata). Only S. colias and T. trecae stock were considered to be in good condition (B/BMSY = 1.7 and 1.4 respectively). The Lc/Lc_opt ratio was ≀ 1 for E. fimbriata and M. cephalus, suggesting that the individuals caught for these species were too small. To reverse these bad stock statuses, catching individuals at Lc_opt, 25, 21, 43 and 18 cm for S. colias, E. fimbriata, M. cephalus and S. pilchardus, respectively should be a natural guarantee against recruitment failure and allow individuals to ensure the long-term survival of populations, in a context of data poor fisheries. In conclusion, this study shows that, despite limitations, the LBB model can provides indicators of stock status for species to encourage management measures, especially in data poor countries. It is hoped that these results can help to better assess many stocks currently considered too data poor to be assessed or at least encourage data collection effort on stocks discerned as in bad or critical status
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