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

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

Etude theorique d'un generateur solaire d'air chaud constitue d'une serre agricole et d'un stockage de chaleur en sous-sol a l'aide de conduits : application au sechage

CNRS T Bordereau / INIST-CNRS - Institut de l'Information Scientifique et TechniqueSIGLEFRFranc

The influence of

Typha Australis is a plant that grows abundantly in fresh water. The proliferation of this plant causes health problems, so several measures have been taken to eradicate this problem such as: cutting the plant, coal production. So this article is about the valorisation of this plant as a bio-based material in order to solve the energy problem in the building. In this study, clay was used as a binder with a given percentage. The mixture of clay and Typha was used as an insulation panel and a comparison was made with a conventional habitat without an insulation panel. A dynamic thermal simulation was performed on TRNSYS to evaluate the influence of the use of this insulation panel on the energy consumption in the building. The results of the comparison showed that the use of this insulation panel, which is a mixture of clay and Typha Australis, reduced the energy requirement by 23%, which is a satisfactory result

Thermal performance of biosourced materials on Buildings: The case of Typha Australis

Developing countries are facing population growth, which leads, on the one hand, to increased requirements for buildings and, on the other hand, to the depletion of fossil fuels along with exposure, of people living in those areas, to some detrimental consequences of climate change. Because of these factors, we propose approaches to control energy consumption in buildings. In some countries, the architectures adopted are not adequate to the environment and climate, resulting in discomfort in those buildings, in such circumstances, residents resort to the use of energy systems, such as heating, ventilation, and air conditioning, which leads to exorbitant electricity bills. Housing consumes 40% of the world's energy and is responsible for a third of greenhouse gas emissions. Optimizing energy needs in buildings is a solution to overcome these problems. For this purpose, there are solutions such as: the design of the building characterized by its shape and envelope, while using less energy-consuming equipment. For several years, the building materials sector has been developing with a particular focus on bio-source materials, which are generally materials with good thermal performance. In order to highlight the thermal performance of bio-source materials, we will study the case of Typha Australis which is a plant of the Typhaceae family that grows abundantly in an aquatic environment mainly in the Senegal River valley.Recent studies showed that Typha Australis has good thermal insulation properties. In order to determine the impact of Typha Australis on a building, a dynamic thermal simulation was carried out using the Trnsys software according to specific scenarios, the Typha was mixed with other local materials and used as a wall insulation panel, the result of the study shows that this fiber has allowed us to optimize energy consumption in a building. Mixing Typha with other materials (e. g. clay) is a promising solution for energy efficiency in buildings

Thermal performance of biosourced materials on Buildings: The case of Typha Australis

Developing countries are facing population growth, which leads, on the one hand, to increased requirements for buildings and, on the other hand, to the depletion of fossil fuels along with exposure, of people living in those areas, to some detrimental consequences of climate change. Because of these factors, we propose approaches to control energy consumption in buildings. In some countries, the architectures adopted are not adequate to the environment and climate, resulting in discomfort in those buildings, in such circumstances, residents resort to the use of energy systems, such as heating, ventilation, and air conditioning, which leads to exorbitant electricity bills. Housing consumes 40% of the world's energy and is responsible for a third of greenhouse gas emissions. Optimizing energy needs in buildings is a solution to overcome these problems. For this purpose, there are solutions such as: the design of the building characterized by its shape and envelope, while using less energy-consuming equipment. For several years, the building materials sector has been developing with a particular focus on bio-source materials, which are generally materials with good thermal performance. In order to highlight the thermal performance of bio-source materials, we will study the case of Typha Australis which is a plant of the Typhaceae family that grows abundantly in an aquatic environment mainly in the Senegal River valley.Recent studies showed that Typha Australis has good thermal insulation properties. In order to determine the impact of Typha Australis on a building, a dynamic thermal simulation was carried out using the Trnsys software according to specific scenarios, the Typha was mixed with other local materials and used as a wall insulation panel, the result of the study shows that this fiber has allowed us to optimize energy consumption in a building. Mixing Typha with other materials (e. g. clay) is a promising solution for energy efficiency in buildings

Investigation of the length and percentage fiber influence of Typha Australis on biosourced composites

This paper discusses the influence and content of Typha Australis fibers on the thermal and mechanical properties of clay composites. The objective is to find a better combination of length and percentage of fibers. This combination will allow to have a good compromise between thermal and mechanical properties. The results found at the end of this study are conclusive. Indeed, the increase of the length and the percentages of fibres improve the thermal properties but the values of the compressive resistances decrease