Socio-Economic Values and Ecological Importance of Balanites aegyptiaca (L.) Del. in Sahelian Agrosystems in western Niger

Balanites aegyptiaca contributes strongly to the resilience of Sahelian populations. All the organs of B. aegyptiaca are used either for food, medicinal purposes or for other services. However, very few studies on the socioeconomic importance of B. aegyptiaca have been conducted in Niger. The main objective of this study was to valorize the knowledge of the populations on the uses of B. aegyptiaca in the Sudan-Sahelian agrosystems of Niger. The study was conducted in the Dosso region. The region was chosen based on its two main agro-climatic zones, characterized by the scarcity of the species in the south and its abundance in the north. A survey was carried out in February 2021 to assess the diversity of uses. The findings revealed that the uses of B. aegyptiaca products are very diversified and varied considerably accross agro-ecological zones. The types of use varied significantly among ethnic groups. The Hausa possessed 88.26% of the use, the Zarma 14.47%, the Peulh 2.63%, the Songhai 1.32%, and Touareg 1.32%. All parts of B. aegyptiaca are used in traditional pharmacopoeia to threat various human and animal illnesses. 68.00% of respondents reported the interaction between Balanites and crops as very beneficial. B. aegyptiaca is prone to a variety of threats. Hence, 97.30% of respondents acknowledged the existence of several diseases and/or insect pests that affect Balanites' organs. Given the importance of this species in the region, more research is required to quantify its contribution to rural household food security and resilience

Caractérisation Hydrogéochimique des Aquifères du Bassin de Timia (Massif de l’Aïr, Nord du Niger)

Le bassin de Timia est situé dans le massif de l’Aïr (Nord du Niger). Dans cette zone, les ressources en eaux sont représentées par les aquifères altérés et fissurés du socle et ceux des alluvions. Ces aquifères, sont sollicités pour l’alimentation des populations, et pour l’irrigation. Ces activités, ont eu comme conséquence la dégradation de la qualité de ces eaux. L’objectif de la présente étude est de déterminer les caractéristiques physico-chimiques et les mécanismes d’acquisition de la minéralisation des eaux souterraines de la zone de Timia. La méthodologie basée sur les approches hydrochimiques et l’analyse en composante principale montre que les facies chimiques des eaux souterraines sont dominés par les facies de type bicarbonatés calciques et magnésiens (52%). Les facies bicarbonatés sodiques et potassiques sont aussi important (29%) tandis que les eaux hyper-bicarbonatées sodiques (13%) sont faiblement représentées. Les sources de la minéralisation des eaux sont principalement de trois types : les apports superficiels (pollution), l’hydrolyse des minéraux silicatés et les activités volcaniques. The Timia Basin is located in the Aïr Massif (Northern Niger). In this area, water resources are represented by altered and fissured basement and alluvial aquifers. These aquifers, are solicited for the water supply, and irrigation. These activities have for consequences the degradation of the quality of these waters. The objective of this study is to determine the physicochemical characteristics and the mechanisms house control the mineralization of groundwater in Timia area. The methodology based on hydrochemical approaches and principal component analysis shows that groundwater chemistry are dominated by calcium-magnesium bicarbonate facies (52%). Sodium-potassium bicarbonate facies are also important (29%) while, sodium hyper-bicarbonate waters (13%) are poorly represented. The sources who controlled the water mineralization are mainly of three types: superficial supply (pollution), hydrolysis of silicate minerals and volcanic activities

Caractérisations Hydroclimatiques et Estimation du Taux de Recharge de la Nappe Libre du Haut Bassin Versant de la Korama, Commune de Droum/Région de Zinder/Niger

La zone d’étude, la Commune de Droum, est située dans le haut bassin versant de la Korama. Celle-ci dispose de plusieurs aquifères, dont l’aquifère phréatique des sables récents ayant des hautes potentialités en eau souterraine. Cet aquifère est très sollicité pour l’approvisionnement en eau de boisson, l’abreuvage des animaux et pour l’irrigation en pleine expansion. Cependant, cet aquifère peu profond reste très sensible à la variabilité climatique ayant affecté la région, comme le reste du sahel, de 1970 à nos jours. L’objectif principal de cette étude est de caractériser les paramètres climatiques puis de quantifier la recharge de cette nappe pendant la période de 1921-2016. La méthodologie adoptée est la caractérisation des différents paramètres climatiques et l’estimation du bilan hydrique à partir de plusieurs techniques (l’indice pluviométrique annuel, le filtre passe-bas de Hanning et les tests statistiques de détection de rupture tels que le Test de Petitt, procédure bayésienne de Lee et Heghinian, segmentation d’Hubert, méthodes Thornthwaite et Penman pour le calcul du bilan) ayant permis d’aboutir à plusieurs résultats. Ainsi, l’analyse de la série pluviométrique montre l’alternance de trois phases: la phase humide de 1921 à 1964, la phase sèche de 1965 à 1997 et la phase normale de 1998 à 2016, et une rupture significative traduisant la baisse de précipitations à partir de 1965 et peu significative mettant en évidence le retour de celles-ci à partir de 1998. Par ailleurs, le bilan hydrologique met en évidence le comportement de la nappe pour ces différentes phases climatiques. On observe, cependant que la recharge de cette nappe en période sèche est relativement faible par rapport à la période humide. Celle-ci provienne probablement de la recharge indirecte car il y a eu une intensification de ruissellement. A partir de 1998, la tendance observée du retour des précipitations a eu comme conséquence, une légère augmentation de la lame d’eau infiltrée par rapport à la période sèche. Toutefois, celle-ci est trop faible quand on le compare à celle de la période humide et aux demandes accrues de cette ressource pour les différents usages. The study area, the municipality of Droum, is located in the high watershed of Korama. It has several aquifers, including the aquifer of recent sands with high potential in groundwater. This aquifer is in great demand for the supply of drinking water, animal watering and for expanding irrigation. However, this shallow aquifer remains very sensitive to the climate variability that has affected the region, like the rest of the Sahel, from 1970 to the present day. The main objective of this study is to characterize the climate parameters and quantify the recharge of this aquifer during the period of 1921-2016. The methodology adopted is the characterization of the various climatic parameters and the estimation of the water balance from several technics (annual pluviometric index, Hanning’s low-pass filter and statistical tests for detecting discontinuities such as it is: Petitt’s test, Lee and Heghinian’s bayesian procedure, Hubert’s segmentation procedure, Thornthwaite and Penman’s methods for water balance calculate) that have led to severalresults. Thus, the analysis of the rainfall series shows the alternation of the three phases : the wet phase from 1921 to 1964, the dry phase from 1965 to 1997 and the normal phase from 1998 to 2016, and a significant discontinuities reflecting the decrease in rainfall starting at 1965 and not very significant highlighting the return of these from 1998. Moreover, the hydrological balance highlights the behavior of the water table for these different climatic phases. It is observed, however, that the recharge of this layer in the dry period is relatively low compared to the wet period. This probably comes from indirect recharge because there has been an intensification of runoff. From 1998, the observed trend of precipitation return has resulted in a slight increase in the infiltrated water slide compared to the dry period. However, it is too weak compared to that of the wet period and the increased demands of this resource for different uses

Organic matter sources and early diagenetic degradation in a tropical peaty marsh (Tritrivakely, Madagascar). Implications for environmental reconstruction during the Sub-Atlantic

Peat samples from a one metre core and living Cyperaceae, collected in Tritrivakely marsh in Madagascar, were studied to determine the organic matter (OM) composition and extent of OM degradation in this core. The study was carried out combining light microscopy observations, bulk analyses, infra-red spectroscopy, hydrolyses of sugars, oxidation of lignin and pyrolyses. In the surface peat, organic matter derived from Cyperaceae undergoes extensive degradation of its basic cell wall components, morphologically revealed by destructuration of plant tissues and their transformation into reddish amorphous organic matter occurring in large amounts all along the core. Two ratios (cinnamic units/lignin and xylose+arabinose/total sugars) were determined as markers of Cyperaceae. It appeared that the vegetation of the marsh remained probably unchanged during the considered accumulation period, i.e. the last 2300 years B.P. Rhamnose, mannose and non-cellulosic glucose probably have a common origin and are mostly derived from bacteria. In contrast, galactose is likely to be a marker of algal source, especially of the diatoms that occur only in the upper part of the core (0-ca. 50 cm). Acid/aldehyde ratios of syringic and vanillic monomers (index of lignin oxidative depolymerisation) and mannose+rhamnose+non-cellulosic glucose/total sugars ratios (reflecting bacterial degradation of hemicelluloses) are positively correlated, and can thus be considered as markers of microbial degradation of the Cyperaceae tissues. The n-alkane/n-alk-1-ene doublets that dominate the pyrolysates of hydrolysed peat samples reflect the contribution of B. braunii algaenan and higher plant suberans, and of condensed lipids mostly derived from higher plants and microalgae. The upper part of the core is characterised by a greater dilution of Cyperaceae-derived compounds by organic matter from microalgae when compared with deeper samples, as recorded by peat bulk features, hydrolysable sugars, lignin oxidation products and pyrolysis products. Two accumulation periods can thus be distinguished in the core: a peaty phase between 2300 years B.P. and ca. 1500 years B.P. (low watertable and strongly limited microalgal growth); a waterlogged marsh, from ca. 1500 years B.P. to the present time, in which a higher water table was longer lasting with a substantial algal production. The environmental variation thus recorded could correspond to a regional climatic change occurring around 1500 years B.P

Caractéristiques Physico-Chimiques Des Eaux De La Nappe Alluviale De La Vallée Du Goulbi N'Kaba Dans La Région De Maradi Au Niger

The Goulbi N'Kaba valley is located in the Maradi region of southcentral Niger. It contains an alluvial aquifer that is used for the drinking water supply, breeding, increasingly more irrigation and for the extractive industries. In addition, this valley is subject to the effects of climate change. A study is needed to improve the knowledge of this water resource, a condition for a better match between the uses and the potentialities of the aquifer. The investigations on the physicochemical parameters and the stable isotopes of the water molecule (oxygen 18 and deuterium), made it possible to reach the following main results: The waters of the alluvial aquifer are slightly acidic, with a pH ranging from 5,2 to 7.2. The mineralization is relatively weak with conductivities between 89,3 and 325 μs/cm, resulting in sodium and calcium bicarbonate facies. These waters are generally good for human consumption and for irrigation. However, in the center of the study area, fluorine and nitrate contents are observed that exceed the WHO guideline values (2006)

Apport Des Images ETM+ Et Du Modèle Numérique De Terrain (MNT) A La Cartographie Des Fractures En Région Montagneuse : Secteur De Timia (Massif De l’Aïr, Nord Du Niger)

Timia is located at the Aïr massifs region. This locality, which is the substratum that constituted the basement formations, has some difficulty of water supply. This present study focuses on fractures mapping to acquire the best knowledge of the fractured aquifer in Timia zone. The methodological approach is based on landsat7 image processing and DEM, especially directional filtering and shaded digital terrain models. These diverse processing has shown complementarity between the satellites images and DEM in linear mapping on the one hand and in establishing a lineaments map on the other hand. The lineament map showed that the fractures network is distributed in the following directions: N0°-N10°, N140°-N170°, N 70°- N100°, and N30°-N50°. These fractures map, which was allowed to increase the density of faults from the previous studies, were used to actualize hydrogeological knowledge and in determining the favorable sites for drilling boreholes in Timia locality

Influenza surveillance capacity improvements in Africa during 2011-2017.

BACKGROUND: Influenza surveillance helps time prevention and control interventions especially where complex seasonal patterns exist. We assessed influenza surveillance sustainability in Africa where influenza activity varies and external funds for surveillance have decreased. METHODS: We surveyed African Network for Influenza Surveillance and Epidemiology (ANISE) countries about 2011-2017 surveillance system characteristics. Data were summarized with descriptive statistics and analyzed with univariate and multivariable analyses to quantify sustained or expanded influenza surveillance capacity in Africa. RESULTS: Eighteen (75%) of 24 ANISE members participated in the survey; their cumulative population of 710 751 471 represent 56% of Africa's total population. All 18 countries scored a mean 95% on WHO laboratory quality assurance panels. The number of samples collected from severe acute respiratory infection case-patients remained consistent between 2011 and 2017 (13 823 vs 13 674 respectively) but decreased by 12% for influenza-like illness case-patients (16 210 vs 14 477). Nine (50%) gained capacity to lineage-type influenza B. The number of countries reporting each week to WHO FluNet increased from 15 (83%) in 2011 to 17 (94%) in 2017. CONCLUSIONS: Despite declines in external surveillance funding, ANISE countries gained additional laboratory testing capacity and continued influenza testing and reporting to WHO. These gains represent important achievements toward sustainable surveillance and epidemic/pandemic preparedness

Impact of mass azithromycin distribution on malaria parasitemia during the low-transmission season in Niger: a cluster-randomized trial.

We assessed the effect of mass azithromycin treatment on malaria parasitemia in a trachoma trial in Niger. Twenty-four study communities received treatment during the wet, high-transmission season. Twelve of the 24 communities were randomized to receive an additional treatment during the dry, low-transmission season. Outcome measurements were conducted at the community-level in children < 1-72 months of age in May-June 2011. Parasitemia was higher in the 12 once-treated communities (29.8%, 95% confidence interval [CI] = 21.5-40.0%) than in the 12 twice-treated communities (19.5%, 95% CI = 13.0-26.5%, P = 0.03). Parasite density was higher in once-treated communities (354 parasites/μL, 95% CI = 117-528 parasites/μL) than in twice-treated communities (74 parasites/μL, 95% CI = 41-202 parasites/μL, P = 0.03). Mass distribution of azithromycin reduced malaria parasitemia 4-5 months after the intervention. The results suggest that drugs with antimalaria activity can have long-lasting impacts on malaria during periods of low transmission

Gradual emergence followed by exponential spread of the SARS-CoV-2 Omicron variant in Africa.

The geographic and evolutionary origins of the SARS-CoV-2 Omicron variant (BA.1), which was first detected mid-November 2021 in Southern Africa, remain unknown. We tested 13,097 COVID-19 patients sampled between mid-2021 to early 2022 from 22 African countries for BA.1 by real-time RT-PCR. By November-December 2021, BA.1 had replaced the Delta variant in all African sub-regions following a South-North gradient, with a peak Rt of 4.1. Polymerase chain reaction and near-full genome sequencing data revealed genetically diverse Omicron ancestors already existed across Africa by August 2021. Mutations, altering viral tropism, replication and immune escape, gradually accumulated in the spike gene. Omicron ancestors were therefore present in several African countries months before Omicron dominated transmission. These data also indicate that travel bans are ineffective in the face of undetected and widespread infection

Retraction.

This is a retraction of 'Gradual emergence followed by exponential spread of the SARS-CoV-2 Omicron variant in Africa' 10.1126/science.add873