Diversité Floristique de la Végétation de la Zone Centrale de l’Habitat des Girafes du Niger, Afrique de l’Ouest

La présente étude analyse la flore et la végétation en lien avec les variables environnementales de la zone centrale de l’habitat de la girafe. Les relevés floristiques ont été réalisés dans 60 placettes de 1000 m² et 94 de 2500 m² à l’aide de la méthode de Braun-Blanquet. Au total 103 espèces végétales ont été recensées. Ces espèces sont reparties en 84 genres dans 43 familles botaniques dont la plus importante est celle des Fabaceae (24 %), suivis par les Poaceae (10 %) les Malvaceae (7 %) et les Combretaceae (6 %). La Classification Hiérarchiques Ascendante a permis de distinguer quatre groupements végétaux au seuil de 74,76 % de similarité. Les variables environnementales comme la géomorphologie, la végétation, la texture du sol, l’altitude ont un effet significatif sur la distribution des espèces et la structuration de la végétation. On note aussi une prédominance des Thérophytes et des espèces à large distribution telles que les Paléotropicales et les Pantropicales dans la zone. Ces résultats révèlent le degré d’exploitation de la végétation de la zone par les populations locales et l’aridité du climat sahélien. This study analyzes the flora and vegetation in relation to the environmental variables of the central zone of the giraffe habitat. Floristic surveys were carried out in 60 plots of 1000 m² and 94 of 2500 m² using the Braun-Blanquet method. A total of 103 plant species have been recorded. These species are divided into 84 genera in 43 botanical families, the most important of which is Fabaceae (9 %), followed by Poaceae Malvaceae (7 %) and Combretaceae (6 %). The Ascending Hierarchical Classification made it possible to distinguish four plant groups at the threshold of 74.76% similarity. Environmental variables such as geomorphology, vegetation, soil texture, and altitude have a significant effect on the distribution of species and the structuring of vegetation. We also note a predominance of Therophytes and widely distributed species such as Paleotropicals and Pantropicals in the zone. These results reveal the degree of exploitation of the vegetation in the area by local populations and the aridity of the Sahelian climate

Flore et Végétation de la Zone Centrale de l’Habitat de la Girafe au Niger, Afrique de l’Ouest

La présente étude analyse la flore et la végétation en lien avec les variables environnementales de la zone centrale de l’habitat de la girafe. Les relevés floristiques ont été réalisés dans 60 placettes de 1000 m² et 94 de 2500 m² à l’aide de la méthode de Braun-Blanquet. Au total 103 espèces végétales ont été recensées. Ces espèces sont reparties en 84 genres dans 43 familles botaniques dont la plus importante est celle des Poaceae (9 %), suivis par les Mimosaceae, les Caesalpiniaceae, les Combretaceae et les Papilionnaceae (6 % chacune). La Classification Hiérarchiques Ascendante a permis de distinguer quatre groupements végétaux au seuil de 74,76 % de similarité. Les variables environnementales comme la géomorphologie, la végétation, la texture du sol, l’altitude ont un effet significatif sur la distribution des espèces et la structuration de la végétation. On note aussi une prédominance des Thérophytes et des espèces à large distribution telles que les Paléotropicales et les Pantropicales dans les groupements. Ces résultats révèlent le degré d’exploitation de la végétation de la zone par les populations locales et l’aridité du climat sahélien.   This study analyzes the flora and vegetation in relation to the environmental variables of the central zone of the giraffe habitat. Floristic surveys were carried out in 60 plots of 1000 m² and 94 of 2500 m² using the Braun-Blanquet method. A total of 103 plant species have been recorded. These species are divided into 84 genera in 43 botanical families, the most important of which is Poaceae (9 %), followed by Mimosaceae, Caesalpiniaceae, Combretaceae and Papilionnaceae (6 % each). The Ascending Hierarchical Classification made it possible to distinguish four plant groups at the threshold of 74.76% similarity. Environmental variables such as geomorphology, vegetation, soil texture, altitude have a significant effect on the distribution of species and the structuring of vegetation. We also note a predominance of Therophytes and widely distributed species such as Paleotropicals and Pantropicals in the groupings. These results reveal the degree of exploitation of the vegetation in the area by local populations and the aridity of Sahelian climate

Caractérisation Phytochimique des Graines et des Pulpes de Lagenaria siceraria (Molina) Standley Utilisées en Pharmacopée dans Sept (6) Régions du Niger

As part of the valorization of medicinal plants in Niger, a phytochemical study was carried out on the seeds and pulp of the species Lagenaria siceraria (Molina) Standley harvested in six (6) regions. The objective was to perform a phytochemical characterization, determine their variability by region and determine the best extraction solvent. Thus, extraction with solvents of increasing polarities and phytochemical screening were carried out, using standard methods, on the various samples. The results obtained show that water is the best solvent for extracting phytocomposites from Lagenaria siceraria seeds and pulp. Extraction efficiency varies by region and solvent. Phytochemical triage tests, carried out on seeds and pulp, revealed the presence of alkaloids, saponosides, flavonoids, tannins, heterosides and an absence of leucoanthocyans, catechols and cyanidins in seed and pulp extracts from certain regions. These results could justify the traditional use of Lagenaria siceraria in the treatment of certain diseases.Dans le cadre de la valorisation des plantes médicinales du Niger, une étude phytochimique a été réalisée sur les graines et les pulpes de l’espèce Lagenaria siceraria (Molina) Standley récoltée dans six (6) régions. L’objectif était de faire une caractérisation phytochimique, de déterminer leur variabilité selon les régions et de déterminer le meilleur solvant d’extraction. Ainsi, une extraction avec des solvants de polarités croissantes et un screening phytochimique ont été effectués, avec des méthodes standards, sur les différents échantillons. Lesrésultats obtenus montrent que l’eau est le meilleur solvant d’extraction des phytocomposés de graines et pulpes de Lagenaria siceraria. Le rendement d’extraction varie selon les régions et en fonction des solvants. Les tests de tri phytochimiques, réalisés sur les graines et pulpes, ont révélés la présence des alcaloïdes, des saponosides, des flavonoïdes, des tanins, des hétérosides et une absence des leucoanthocyanes, des catéchols et des cyanidines dans les extraits de graine et pulpe de certaines régions. Ces résultats pourraient justifiés l’utilisation traditionnelle de Lagenaria siceraria dans le traitement de certaines maladies

Disentangling the role of Africa in the global spread of H5 highly pathogenic avian influenza

The role of Africa in the dynamics of the global spread of a zoonotic and economicallyimportant virus, such as the highly pathogenic avian influenza (HPAI) H5Nx of the Gs/GD lineage, remains unexplored. Here we characterise the spatiotemporal patterns of virus diffusion during three HPAI H5Nx intercontinental epidemic waves and demonstrate that Africa mainly acted as an ecological sink of the HPAI H5Nx viruses. A joint analysis of host dynamics and continuous spatial diffusion indicates that poultry trade as well as wild bird migrations have contributed to the virus spreading into Africa, with West Africa acting as a crucial hotspot for virus introduction and dissemination into the continent. We demonstrate varying paths of avian influenza incursions into Africa as well as virus spread within Africa over time, which reveal that virus expansion is a complex phenomenon, shaped by an intricate interplay between avian host ecology, virus characteristics and environmental variables.USAID under the OSRO/GLO/501/USA and OSRO/GLO/507/USA projects and by European Union’s Horizon 2020 research and innovation programme under grant agreement No 727922 (DELTAFLU). The European Research Council under the European Unionʼs Horizon 2020 research and innovation programme (grant agreement no. 725422-ReservoirDOCS). P.L. acknowledges support by the Research Foundation – Flanders FWO, G066215N, G0D5117N and G0B9317N). B.V. is a postdoctoral research fellow supported by the FWO.http://www.nature.com/naturecommunicationsam2020Microbiology and Plant Patholog

Disentangling the role of Africa in the global spread of H5 highly pathogenic avian influenza

The role of Africa in the dynamics of the global spread of a zoonotic and economically-important virus, such as the highly pathogenic avian influenza (HPAI) H5Nx of the Gs/GD lineage, remains unexplored. Here we characterise the spatiotemporal patterns of virus diffusion during three HPAI H5Nx intercontinental epidemic waves and demonstrate that Africa mainly acted as an ecological sink of the HPAI H5Nx viruses. A joint analysis of host dynamics and continuous spatial diffusion indicates that poultry trade as well as wild bird migrations have contributed to the virus spreading into Africa, with West Africa acting as a crucial hotspot for virus introduction and dissemination into the continent. We demonstrate varying paths of avian influenza incursions into Africa as well as virus spread within Africa over time, which reveal that virus expansion is a complex phenomenon, shaped by an intricate interplay between avian host ecology, virus characteristics and environmental variables.status: publishe

External quality assessment of Rift Valley fever diagnosis in countries at risk of the disease: African, Indian Ocean and Middle-East regions

International audienceRift Valley fever virus (RVFV), an arbovirus belonging to the Phlebovirus genus of the Phenuiviridae family, causes the zoonotic and mosquito-borne RVF. The virus, which primarily affects livestock (ruminants and camels) and humans, is at the origin of recent major outbreaks across the African continent (Mauritania, Libya, Sudan), and in the South-Western Indian Ocean (SWIO) islands (Mayotte). In order to be better prepared for upcoming outbreaks, to predict its introduction in RVFV unscathed countries, and to run efficient surveillance programmes, the priority is harmonising and improving the diagnostic capacity of endemic countries and/or countries considered to be at risk of RVF. A serological inter-laboratory proficiency test (PT) was implemented to assess the capacity of veterinary laboratories to detect antibodies against RVFV. A total of 18 laboratories in 13 countries in the Middle East, North Africa, South Africa, and the Indian Ocean participated in the initiative. Two commercial kits and two in-house serological assays for the detection of RVFV specific IgG antibodies were tested. Sixteen of the 18 participating laboratories (88.9%) used commercial kits, the analytical performance of test sensitivity and specificity based on the seroneutralisation test considered as the reference was 100%. The results obtained by the laboratories which used the in-house assay were correct in only one of the two criteria (either sensitivity or specificity). In conclusion, most of the laboratories performed well in detecting RVFV specific IgG antibodies and can therefore be considered to be prepared. Three laboratories in three countries need to improve their detection capacities. Our study demonstrates the importance of conducting regular proficiency tests to evaluate the level of preparedness of countries and of building a network of competent laboratories in terms of laboratory diagnosis to better face future emerging diseases in emergency conditions