Soil moisture in forest island and adjacent ecosystems in Sub-Saharan Region

Forest islands are widely distributed throughout West Africa savanna landscape. Stated as direct outcome of anthropogenic activity, these mosaics are often found around villages and are known for their unique and luxuriant characteristics of tropical rainforest. Althought significant studies focus on their ecology, works on edaphic factors that govern their establishment are very scare. The objective of the current study was to evaluate soil moisture dynamics in forest islands compared to that of surrounding savannas and farmlands at five sites located along a precipation gradient in Burkina Faso. For two years, from 2016 to 2017, soil moisture was monitored at a depth of 0-80 cm using a neutron probe. The results highlighted a seasonal pattern ranging from 42±2% during the heavy rainy month (August) to 16±1% during the dry season (October-November). Significant differences in soil moisture content soil water profile and water stock at depth 0 to 80 cm were recorded between locations and land use patterns. In general, soil moisture was on average 58% less in forest island than in croplands across sites. Soil moisture content was lower in topsoil (0-20 cm) compared to deeper soil (40-80 cm). The Study demonstrated evident link of soil moisture dynamic with rainfall and the vegetation pattern

Serotype Profile of Nasopharyngeal Isolates of Streptococcus pneumoniae Obtained from Children in Burkina Faso before and after Mass Administration of Azithromycin.

Mass drug administration (MDA) with azithromycin (AZ) has been used successfully to control trachoma. However, several studies have shown that MDA with AZ has led to the emergence of resistance to AZ in Streptococcus pneumoniae. The emergence of resistance to AZ has also been observed when this antibiotic was combined with the antimalarials used for seasonal malaria chemoprevention (SMC). The development of antibiotic resistance, including resistance to AZ, is sometimes associated with the emergence of a bacterial clone that belongs to a specific serotype. We hypothesize that the increase in resistance of S. pneumoniae observed after 3 years of SMC with AZ might be associated with a change in the distribution of pneumococcal serotypes. Therefore, 698 randomly selected isolates from among the 1,468 isolates of S. pneumoniae obtained during carriage studies undertaken during an SMC plus AZ trial were serotyped. A polymerase chain reaction (PCR) multiplex assay using an algorithm adapted to the detection of the pneumococcal serotypes most prevalent in African countries was used for initial serotyping, and the Quellung technique was used to complement the PCR technique when necessary. Fifty-six serotypes were detected among the 698 isolates of S. pneumoniae. A swift appearance and disappearance of many serotypes was observed, but some serotypes including 6A, 19F, 19A, 23F, and 35B were persistent. The distribution of serotypes between isolates obtained from children who had received AZ or placebo was similar. An increase in AZ resistance was seen in several serotypes following exposure to AZ. Mass drug administration with AZ led to the emergence of resistance in pneumococci of several different serotypes and did not appear to be linked to the emergence of a single serotype

Pooled Multicenter Analysis of Cardiovascular Safety and Population Pharmacokinetic Properties of Piperaquine in African Patients with Uncomplicated Falciparum Malaria.

Dihydroartemisinin-piperaquine has shown excellent efficacy and tolerability in malaria treatment. However, concerns have been raised of potentially harmful cardiotoxic effects associated with piperaquine. The population pharmacokinetics and cardiac effects of piperaquine were evaluated in 1,000 patients, mostly children enrolled in a multicenter trial from 10 sites in Africa. A linear relationship described the QTc-prolonging effect of piperaquine, estimating a 5.90-ms mean QTc prolongation per 100-ng/ml increase in piperaquine concentration. The effect of piperaquine on absolute QTc interval estimated a mean maximum QTc interval of 456?ms (50% effective concentration of 209 ng/ml). Simulations from the pharmacokinetic-pharmacodynamic models predicted 1.98 to 2.46% risk of having QTc prolongation?of >60 ms in all treatment settings. Although piperaquine administration resulted in QTc prolongation, no cardiovascular adverse events were found in these patients. Thus, the use of dihydroartemisinin-piperaquine should not be limited by this concern. (This study has been registered at ClinicalTrials.gov under identifier NCT02199951.)

Impact of a package of diagnostic tools, clinical algorithm, and training and communication on outpatient acute fever case management in low- and middle-income countries: protocol for a randomized controlled trial.

BACKGROUND: The management of acute febrile illnesses places a heavy burden on clinical services in many low- and middle-income countries (LMICs). Bacterial and viral aetiologies of acute fevers are often clinically indistinguishable and, in the absence of diagnostic tests, the 'just-in-case' use of antibiotics by many health workers has become common practice, which has an impact on drug-resistant infections. Our study aims to answer the following question: in patients with undifferentiated febrile illness presenting to outpatient clinics/peripheral health centres in LMICs, can we demonstrate an improvement in clinical outcomes and reduce unnecessary antibiotic prescription over current practice by using a combination of simple, accurate diagnostic tests, clinical algorithms, and training and communication (intervention package)? METHODS: We designed a randomized, controlled clinical trial to evaluate the impact of our intervention package on clinical outcomes and antibiotic prescription rates in acute febrile illnesses. Available, point-of-care, pathogen-specific and non-pathogen specific (host markers), rapid diagnostic tests (RDTs) included in the intervention package were selected based on pre-defined criteria. Nine clinical study sites in six countries (Burkina Faso, Ghana, India, Myanmar, Nepal and Uganda), which represent heterogeneous outpatient care settings, were selected. We considered the expected seasonal variations in the incidence of acute febrile illnesses across all the sites by ensuring a recruitment period of 12 months. A master protocol was developed and adapted for country-specific ethical submissions. Diagnostic algorithms and choice of RDTs acknowledged current data on aetiologies of acute febrile illnesses in each country. We included a qualitative evaluation of drivers and/or deterrents of uptake of new diagnostics and antibiotic use for acute febrile illnesses. Sample size estimations were based on historical site data of antibiotic prescription practices for malarial and non-malarial acute fevers. Overall, 9 semi-independent studies will enrol a minimum of 21,876 patients and an aggregate data meta-analysis will be conducted on completion. DISCUSSION: This study is expected to generate vital evidence needed to inform policy decisions on the role of rapid diagnostic tests in the clinical management of acute febrile illnesses, with a view to controlling the rise of antimicrobial resistance in LMICs. TRIAL REGISTRATION: Clinicaltrials.gov NCT04081051 . Registered on 6 September 2019. Protocol version 1.4 dated 20 December 2019

Pantropical variability in tree crown allometry

Aim Tree crowns determine light interception, carbon and water exchange. Thus, understanding the factors causing tree crown allometry to vary at the tree and stand level matters greatly for the development of future vegetation modelling and for the calibration of remote sensing products. Nevertheless, we know little about large‐scale variation and determinants in tropical tree crown allometry. In this study, we explored the continental variation in scaling exponents of site‐specific crown allometry and assessed their relationships with environmental and stand‐level variables in the tropics. Location Global tropics. Time period Early 21st century. Major taxa studied Woody plants. Methods Using a dataset of 87,737 trees distributed among 245 forest and savanna sites across the tropics, we fitted site‐specific allometric relationships between crown dimensions (crown depth, diameter and volume) and stem diameter using power‐law models. Stand‐level and environmental drivers of crown allometric relationships were assessed at pantropical and continental scales. Results The scaling exponents of allometric relationships between stem diameter and crown dimensions were higher in savannas than in forests. We identified that continental crown models were better than pantropical crown models and that continental differences in crown allometric relationships were driven by both stand‐level (wood density) and environmental (precipitation, cation exchange capacity and soil texture) variables for both tropical biomes. For a given diameter, forest trees from Asia and savanna trees from Australia had smaller crown dimensions than trees in Africa and America, with crown volumes for some Asian forest trees being smaller than those of trees in African forests. Main conclusions Our results provide new insight into geographical variability, with large continental differences in tropical tree crown allometry that were driven by stand‐level and environmental variables. They have implications for the assessment of ecosystem function and for the monitoring of woody biomass by remote sensing techniques in the global tropics

Chapitre 14. Pratiques paysannes de gestion des pesticides dans les bas-fonds rizicoles

Introduction En Afrique de l’Ouest, les terres inondables constituent des milieux à forts enjeux tant agricoles qu’environnementaux (De Noray, 2003 ; Blein et al., 2008). D’une part, ce sont des zones humides qui assurent les fonctions essentielles de conservation des eaux et de la biodiversité. D’autre part, ces milieux, dotés d’un grand potentiel agricole compte tenu de leurs ressources en eau et de leurs sols, sont de plus en plus convoités par de multiples usagers. Les bas-fonds aménagés ..

Soil aggregate stability of forest islands and adjacent ecosystems in West Africa

Purpose: In the mesic savannas of West Africa, areas around villages of relatively tall and dense forest vegetation are often found. These ‘forest islands’ are presumably the direct outcome of human activity. To better understand these patches with relatively luxuriant vegetation, our study focused on how they influence soil aggregate stability- a key indicator of soil resilience to degradation through erosion. We compared the proportion of stable soil aggregates of the forest islands with nearby croplands and natural savanna vegetation across a precipitation transect in West Africa for which mean annual precipitation at the study sites ranges from 0.80 to 1.27 m a−1. Methods: Soil samples were taken from 0–5 cm and 5–10 cm depths and stability of soil aggregate groups with diameters: > 500 μm, 500–250 μm and 250–53 μm (viz. “macroaggregates”, “mesoaggregates” and “microaggregates” respectively) determined using the wet sieving method. Results: The results showed significantly (p < 0.05) higher proportion of stable soil meso- and macro-aggregates in forest islands and natural savanna than in agricultural soils. Although there was no effect of land-use type on microaggregate stability, there was a strong tendency for the stable microaggregates across all land use types to increase with increasing precipitation. Soil organic carbon and iron oxides contents were the most important factors influencing meso and macro-aggregate stability in the West African ecosystems. Conclusion: We conclude that formation of stable soil microaggregates in the West African ecosystems was climate or precipitation driven whereas the more labile and larger-size groups of meso-and macro- aggregates was land-use driven. The study provides first insights in soil quality processes in a poorly studied but unique phenomenon of man-made forest islands in West Africa

High adherence level to artemisinin-based combination therapies in rural settlement 11 years after their introduction in the health system, Nanoro, Burkina Faso.

In 2005, Burkina Faso changed its first-line treatment for uncomplicated malaria from chloroquine to artemisinin-based combination therapies (ACTs). Patient adherence to ACTs regimen is a keystone to achieve the expected therapeutic outcome and prevent the emergence and spread of parasite resistance. Eleven years after the introduction of ACTs in the health system, this study aimed to measure adherence level of patients in rural settlement and investigate the determinants of nonadherence.SCOPUS: ar.jinfo:eu-repo/semantics/publishe