Effets des rhizobactéries PGPR sur le rendement et les teneurs en macroéléments du maïs sur sol ferralitique non dégradé au Sud-Bénin

L’objectif de l’étude est d’évaluer les effets de 15 rhizobactéries promotrices de croissance végétative (PGPR en Anglais) sur le rendement et l’état nutritionnel des plants de maïs sur sol ferralitique non dégradé du Sud-Bénin. Les semences de maïs ont été inoculées avec des concentrations microbiennes d’environ 108 UFC/ml. Les teneurs en azote, en phosphore et en potassium d’échantillons de plants de maïs ont été déterminées. Les valeurs de rendement du maïs ont été soumises à une analyse de la variance à deux facteurs. Les rhizobactéries Pseudomonas fluorescens ont induit le rendement de maïs le plus élevé, dépassant de 41,46% le rendement de maïs obtenu avec l’inoculation de P. putida et de 118,05% le rendement de maïs obtenu au niveau des plants non inoculés. Les rendements de maïs induits par P. putida et Azospirillium lipoferum sont supérieurs respectivement de 54,17% et de 26,39% au rendement obtenu au niveau des plants non inoculés. Les résultats obtenus augurent de la possibilité d’utiliser les rhizobactéries PGPR comme des engrais biologiques pour une production durable de maïs. Au Sud du Bénin, où la pression démographique est forte et la baisse de la fertilité des sols croissante, l’utilisation de méthodes biologiques pour accroître les récoltes est une solution incontournable.Mots clés: Rhyzobactéries, Rendement, Maïs, Sol ferralitique, Béni

Assessment of the proportion of neonates and children in low and middle income countries with access to a healthcare facility: A systematic review

<p>Abstract</p> <p>Background</p> <p>Comprehensive antenatal, perinatal and early postnatal care has the potential to significantly reduce the 3.58 million neonatal deaths that occur annually worldwide. This paper systematically reviews data on the proportion of neonates and children < 5 years of age that have access to health facilities in low and middle income countries. Gaps in available data by WHO region are identified, and an agenda for future research and advocacy is proposed.</p> <p>Methods</p> <p>For this paper, "utilization" was used as a proxy for "access" to a healthcare facility, and the term "facility" was used for any clinic or hospital outside of a person's home staffed by a "medical professional". A systematic literature search was conducted for published studies of children up to 5 years of age that included the neonatal age group with an illness or illness symptoms in which health facility utilization was quantified. In addition, information from available Demographic and Health Surveys (DHS) was extracted.</p> <p>Results</p> <p>The initial broad search yielded 2,239 articles, of which 14 presented relevant data. From the community-based neonatal studies conducted in the Southeast Asia region with the goal of enhancing care-seeking for neonates with sepsis, the 10-48% of sick neonates in the studies' control arms utilized a healthcare facility. Data from cross-sectional surveys involving young children indicate that 12 to 86% utilizing healthcare facilities when sick. From the DHS surveys, a global median of 58.1% of infants < 6 months were taken to a facility for symptoms of ARI.</p> <p>Conclusions</p> <p>There is a scarcity of data regarding the access to facility-based care for sick neonates/young children in many areas of the world; it was not possible to generalize an overall number of neonates or young children that utilize a healthcare facility when showing signs and symptoms of illness. The estimate ranges were broad, and there was a paucity of data from some regions. It is imperative that researchers, advocates, and policy makers join together to better understand the factors affecting health care utilization/access for newborns in different settings and what the barriers are that prevent children from being taken to a facility in a timely manner.</p

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

Dendrometrical study of Acacia auriculiformis A. Cunn. in mixed stands on claysoils in Benin

Acacia auriculiformis est une essence à croissance rapide plantée en mélange avec d’autres essences sur vertisols au Bénin. Un inventaire de 11 peuplements âgés de 7 à 9 ans a été effectué en vue de déterminer divers paramètres dendrométriques relatifs à cette essence en mélange. Pour ceux-ci l’étude n’a révélé aucune différence statistiquement significative entre les associations d’essences au niveau 0,05 quels que soient l’âge des peuplements et la nature des associations. Néanmoins, les valeurs les plus élevées de diamètre du pied (portant un ou plusieurs arbres) de surface terrière moyenne sont observées pour les associations d’essences incluant Leucaena leucocephala. De plus, le volume branche des pieds d’Acacia diminue avec l’augmentation du nombre d’arbres par pied. Le tarif de cubage le plus approprié pour l’estimation des volumes des pieds est celui qui prend en compte le diamètre quadratique du pied et la hauteur totale. Par ailleurs, les associations d’essences n’ont aucun impact sur le profil des arbres qui reste constant d’une association à l’autre. L’estimation des coefficients d’empilage et d’exploitabilité met en évidence un volume enstéré équivalent à 144 % du volume réel.Acacia auriculiformis is a fast growing species planted on vertisols in Benin. An inventory of 11 mixed stands of Acacia, which are 7 to 9 years old, has been realized to estimate growth parameters of the stands. The present study shows that, for the dendrometrical parameters, there is no difference between species associations at a 0.05 significance level. Nevertheless, the largest values of quadratic mean diameter of the stems foot are observed in the species associations including Leucaena leucocephala. Moreover, the branch volume decreases with the increasing of the number of stems per tree. The most appropriate volume function for Acacia auriculiformis is the one that takes into account the diameter of the stems foot and the total height. Otherwise, the species associations do not influence the profile of Acacia trees, which is constant within the associations. The predicted conversion and cutting coefficients show that the stacked wood volume represents about 144 % of the real stand volume

Combating cholera epidemics by targeting reservoirs of infection and transmission routes: A review

Objectives: To determine the parameters which can be investigated for prevention and effective control of cholera. Data sources: Literature search on compact disk-read only memory (CD-ROM), medline and internet, using the key words: cholera outbreaks, and cholera transmission. A few reviews were manually reviewed. Study selection: Relevant studies or articles on cholera outbreaks and transmission worldwide, with special reference to Kenya is included in the review. Data extraction: From individual study or articles. Data synthesis: Information on cholera epidemics worldwide and in Kenya is synchronized under the headings; Introduction, History and predisposing factors, Current situation, Bioecology and transmission patterns, and, Use of molecular epidemiological and geographic information system (GIS) techniques in mapping out the bioecology, reservoirs and transmission routes of cholera. Conclusion: Cholera can be prevented and controlled more effectively at environment level. This requires a multi-disciplinary approach including poverty alleviation. (East African Medical Journal: 2002 79(3): 150-155

Comparaison empirique des estimateurs des taux d'erreur en analyse discriminante

peer reviewedMonte Carlo experiments are performed to compare twenty estimators or error rates in discriminant analysis in the case of two populations and linear classification rule. Several distributions (normal, chi-square and beta) have been considered. Estimators eOS (for actual and expected error rate) and eB (for optimal error rate) are the best, except for distributions very different from normal distributions. The e632 estimator is the best non parametric estimator. This estimator is better than parmetric estimators for distributions very different from normal distributions.A partir de ces simulations, on compare les performances de vingt estimateurs des taux d'erreur en analyse discriminante, dans le cas de deux populations et pour la règle de discrimination linéaire. Différentes distributions (normale, chi-2 et bêta) ont été considérées. On conclut que l'estimateur eOS (pour le taux réel et le taux attendu) et eB (pour le taux optimal) sont les estimateurs les meilleurs, sauf pour des distributions s'écartant très nettement des populations normales. L'estimateur e632 est le meilleur estimateur non paramétrique. Il est préférable aux estimateurs paramétriques si les distributions sont très différentes des distributions normales

Typologie Et Structure Des Populations Naturelles De Pentadesma Butyracea Dans La Zone Soudano-Guineenne Du Benin

La présente étude, conduite dans la région soudano-guinéenne du centre Bénin, a pour objectif la caractérisation écologique de Pentadesma butyracea, une espèce vulnérable au Bénin, à travers l’inventaire, la typologie et la caractérisation structurale de ses populations naturelles. Les inventaires floristiques et dendrométriques ont été faits dans cent placeaux de 500 m2, de longueur et largueur variables, dans tous les sites de forêts galeries à dominance P. butyracea. Les données collectées sont l’abondance, la richesse spécifique, la densité, la surface terrière, l’Indice Shannon et l’équitabilité de Pielou. Dans la région soudano-guinéenne du Centre Bénin, P. butyracea est présent dans 76 sites avec une abondance de 1.132 individus adultes (dbh ≥ 10 cm). Sur la base des caractéristiques écologiques des sites, cinq populations de P. butyracea ont été identifiées. Il s’agit des populations de Bassila, Koura, Manigri, Pénéssoulou et Agbassa, qui sont différentes sur le plan statistique pour chacun des paramètres écologiques à savoir la densité, la surface terrière, la richesse spécifique, l’Indice de Shannon et l’Equitabilité de Pielou (Prob. &lt; 0,001). La structure en diamètre de l’espèce dans la plupart des sites est en cloche avec une dissymétrie droite caractéristique des peuplements monospécifiques jeunes. Trois facteurs/gradients (i.e. climat, formations végétales et pression anthropique) expliquent au mieux la typologie et la structure en diamètre des cinq populations discriminées. Il est préconisé comme stratégies de protection et exploitation durables de P. butyracea dans le milieu d’étude la conservation in situ et ex situ, le respect de la législation forestière en matière de protection des forêts galeries, les essais de domestication et la sensibilisation des populations à la limitation des pressions et préservation de cette espèce vulnérable auBénin.Mots clés : Ligneux, Usage Multiple, Pentadesma butyracea, répartition géographique, structure, Bénin.The present study, conducted in the Soudano-guinean region of centre Benin, aimed to characterize the ecology of Pentadesma butyracea, a vulnerable multipurpose species in Benin Republic. All the riparian forest sites where the species was present have been inventoried to map its spatial distribution and quantify its abundance. Floristic and dendrometric relevés were done in 100 plots, each 500 m² in size, in the P. butyracea dominated riparian forest sites to assessed the flora diversity and the structure of the targeted species. In the soudano-guinean region of centre Benin, P. butyracea was present in 76 riparian forest sites with an overall abundance of 1.132 stems (dbh ≥ 10 cm). The values of trees density, basal area, species richness, Shannon diversity index and Pielou equitability index permitted to discriminated five P. butyracea populations (i.e. Bassila, Koura, Manigri, Pénéssoulou and Agbassa) that were significantly different for all the parameters used for the typology (Prob. &lt; 0,001). Three factors/gradients (i.e. climate, vegetation, anthropogenic disturbance) were the underlying factors of the typology and structure of the discriminated populations. The stem diameter structure of P. butyracea in most of the stands had a Gaussian shape with however a right-dissymmetry, characteristic of young monospecific populations. Among the strategies for sustainable protection and uses of P. butyracea in the study area we suggest to promote in situ and ex situ conservation, to enforce of the forest law regarding the protection of riparian forests, to undertake domestication trials and to raise awareness among local people as a means to reduce anthropogenic disturbance and preserve remnants populations of this vulnerable species in Benin.Keywords : Tree Species, Pentadesma butyracea, spatial distribution, structure, Benin.Article in Frenc

Caractérisation des rhizobactéries potentiellement promotrices de la croissance végétative du maïs dans différents agrosystèmes du Sud-Bénin

L&rsquo;objectif de cette &eacute;tude est de caract&eacute;riser les rhizobact&eacute;ries potentiellement promotrices de la croissance v&eacute;g&eacute;tative ou encore en anglais &laquo; plant growth promoting rhizobacteria&raquo; (PGPR) vivant dans la rhizosph&egrave;re de douze (12) diff&eacute;rentes zones agro&eacute;cologiques du sud-B&eacute;nin. Un &eacute;chantillon composite de sol et de racines des plants de ma&iuml;s est pr&eacute;lev&eacute; au niveau de 4 diff&eacute;rents champs de producteurs par zone agro&eacute;cologique. Des analyses agrochimiques et microbiologiques sont faites sur ces &eacute;chantillons. Les r&eacute;sultats montrent que la flore totale des sols &eacute;tudi&eacute;s est riche en rhizobact&eacute;ries. Quinze (15) esp&egrave;ces de PGPR diff&eacute;rentes sont identifi&eacute;es &agrave; de fortes concentrations dans tous les &eacute;chantillons de sols et de racines. Il s&rsquo;agit de trois esp&egrave;ces de Pseudomonas, trois esp&egrave;ces de Streptomyces, huit esp&egrave;ces de Bacillus et une esp&egrave;ce de Azospirillium. Les sols du sud-B&eacute;nin contiennent naturellement des rhizobact&eacute;ries potentiellement promotrices de croissance v&eacute;g&eacute;tative. Il ne se d&eacute;gage pas de lien entre les propri&eacute;t&eacute;s chimiques des sols des diff&eacute;renteszones d&rsquo;&eacute;tude et la distribution des rhizobact&eacute;ries PGPR