Effets de la fertilisation potassique des sols ferrugineux tropicaux sur la nutrition minérale et la productivité du cotonnier (Gossypium hirsutum L.) au Burkina Faso

L'étude a été conduite pendant deux années, dans deux stations expérimentales situées à l’Ouest et à l’Est du Burkina Faso, pour évaluer l'efficacité de la fertilisation potassique sur les rendements du cotonnier et ses effets sur les caractéristiques technologiques de la fibre de coton. Les traitements étaient constitués par lafumure minérale vulgarisée sur le cotonnier (150 kg ha-1 de 14-18-18-6S-1B + 50 kg ha-1 d'urée) à laquelle cinq doses de chlorure de potassium (0; 25; 50; 75 et 100 kg ha-1 de KCl) ont été associées. Dans un dispositif expérimental en blocs de Fisher, la nutrition minérale du cotonnier, le rendement en coton graine et ses composantes ainsi que les caractéristiques technologiques de la fibre ont été les paramètres mesurés. Les doses de potassium ont significativement amélioré la nutrition potassique du cotonnier à 70 jours après levée ainsi que les rendements en coton graine. Les doses de 75 et 100 kg ha-1de KCl étaient statistiquement équivalentes à la dose de 50 kg ha-1 de KCl qui a induit, par rapport au témoin sans KCl, une amélioration du rendement de + 139 kg ha-1 et + 214 kg ha-1 de coton graine, respectivement à Kouaré et Farako-bâ. Par rapport au témoin sans KCl, les doses de potassium n'ont pas eu d'effets significatifs sur le nombre de capsules, le pourcentage de fibre, le seed index (poids de 100 graines) ainsi que les caractéristiques technologiques de la fibre. En dépit de l'utilisation de la fumure minérale vulgarisée, les bilans potassiques étaient déficitaires. Mais les apports de KCl ont permis d'atténuer ces déficits et même d'assurer des bilans excédentaires. L'apport de 50 kg ha-1 de KCl pourrait être associé à la fumure minérale vulgarisée sur le cotonnier pour son efficacité sur le rendement et l'amélioration du bilan potassique du sol.© 2016 International Formulae Group. All rights reserved.Mots clés: Sol ferrugineux, potassium, cotonnier, rendement, Burkina FasoEnglish Title:  Effects of potassium fertilization of lixisols on mineral nutrition and productivity of cotton (Gossypium hirsutum L.) in Burkina FasoEnglish AbstractTo evaluate potassium fertilization effects on the cotton yield and fiber quality characteristics, two years study was conducted on two experimental stations, located in West and East Burkina Faso. Treatments were five rates of potassium chloride (0; 25; 50; 75 and 100 kg ha-1 KCl) associated to the recommended mineral fertilizer (150 kg ha-1 of 14-18-18-6S-1B + 50 kg ha-1 urea) of cotton. The treatments were arranged in a randomized block design. The cotton plant nutrition, yields and its components and fiber characteristics were evaluated. The cotton plant K nutrition at 70 days after emergence and cotton-seed yields were significantly improved by applied rates of potassium compared to the control. KCl application rates of 75 and 100 kg ha -1 were statistically equivalent to 50 kg ha -1 which gave a surplus cotton-seed production of 139 kg ha-1 and 214 kg ha-1, respectively in Kouaré and Farako-bâ. Compared to the control without KCl, potassium didn’t have significant effects on bolls production, fiber yield and quality, and seed index. Despite the use of recommended mineral fertilization rate, the soil K balance was negative. Potassium application reduces the K deficits and ensures positive soil K balance. Use of KCl at 50 kg ha-1 with the recommended mineral fertilizer could be done to improve cotton yield and soil K balance.© 2016 International Formulae Group. All rights reserved.Keywords: Lixisols, potassium, cotton, yield, Burkina Fas

Interleukin-10 and soluble tumor necrosis factor receptor II are potential biomarkers of Plasmodium falciparum infections in pregnant women: a case-control study from Nanoro, Burkina Faso.

BACKGROUND: Diagnosis of malaria in pregnancy is problematic due to the low sensitivity of conventional diagnostic tests (rapid diagnostic test and microscopy), which is exacerbated due to low peripheral parasite densities, and lack of clinical symptoms. In this study, six potential biomarkers to support malaria diagnosis in pregnancy were evaluated. METHODS: Blood samples were collected from pregnant women at antenatal clinic visits and at delivery. Microscopy and real-time PCR were performed for malaria diagnosis and biomarker analyses were performed by ELISA (interleukin 10, IL-10; tumor necrosis factor-α, TNF-α; soluble tumor necrosis factor receptor II, sTNF-RII; soluble fms-like tyrosine kinase 1, sFlt-1; leptin and apolipoprotein B, Apo-B). A placental biopsy was collected at delivery to determine placental malaria. RESULTS: IL-10 and sTNF-RII were significantly higher at all time-points in malaria-infected women (p < 0.001). Both markers were also positively associated with parasite density (p < 0.001 and p = 0.003 for IL-10 and sTNF-RII respectively). IL-10 levels at delivery, but not during pregnancy, were negatively associated with birth weight. A prediction model was created using IL-10 and sTNF-RII cut-off points. For primigravidae the model had a sensitivity of 88.9% (95%CI 45.7-98.7%) and specificity of 83.3% (95% CI 57.1-94.9%) for diagnosing malaria during pregnancy. For secundi- and multigravidae the sensitivity (81.8% and 56.5% respectively) was lower, while specificity (100.0% and 94.3% respectively) was relatively high. Sub-microscopic infections were detected in 2 out of 3 secundi- and 5 out of 12 multigravidae. CONCLUSIONS: The combination of biomarkers IL-10 and sTNF-RII have the potential to support malaria diagnosis in pregnancy. Additional markers may be needed to increase sensitivity and specificity, this is of particular importance in populations with sub-microscopic infections or in whom other inflammatory diseases are prevalent

Interleukin-10 and soluble tumor necrosis factor receptor II are potential biomarkers of Plasmodium falciparum infections in pregnant women: a case-control study from Nanoro, Burkina Faso

Background: Diagnosis of malaria in pregnancy is problematic due to the low sensitivity of conventional diagnostic tests (rapid diagnostic test and microscopy), which is exacerbated due to low peripheral parasite densities, and lack of clinical symptoms. In this study, six potential biomarkers to support malaria diagnosis in pregnancy were evaluated.Methods: Blood samples were collected from pregnant women at antenatal clinic visits and at delivery. Microscopy and real-time PCR were performed for malaria diagnosis and biomarker analyses were performed by ELISA (interleukin 10, IL-10; tumor necrosis factor-α, TNF-α; soluble tumor necrosis factor receptor II, sTNF-RII; soluble fms-like tyrosine kinase 1, sFlt-1; leptin and apolipoprotein B, Apo-B). A placental biopsy was collected at delivery to determine placental malaria.Results: IL-10 and sTNF-RII were significantly higher at all time-points in malaria-infected women (p < 0.001). Both markers were also positively associated with parasite density (p < 0.001 and p = 0.003 for IL-10 and sTNF-RII respectively). IL-10 levels at delivery, but not during pregnancy, were negatively associated with birth weight. A prediction model was created using IL-10 and sTNF-RII cut-off points. For primigravidae the model had a sensitivity of 88.9% (95%CI 45.7–98.7%) and specificity of 83.3% (95% CI 57.1–94.9%) for diagnosing malaria during pregnancy. For secundi- and multigravidae the sensitivity (81.8% and 56.5% respectively) was lower, while specificity (100.0% and 94.3% respectively) was relatively high. Sub-microscopic infections were detected in 2 out of 3 secundi- and 5 out of 12 multigravidae.Conclusions: The combination of biomarkers IL-10 and sTNF-RII have the potential to support malaria diagnosis in pregnancy. Additional markers may be needed to increase sensitivity and specificity, this is of particular importance in populations with sub-microscopic infections or in whom other inflammatory diseases are prevalent

Ecological challenges for the buffer zone management of protected areas of forest-savannah mosaic in West Africa

In sub-Saharan Africa, the management of buffer zones around protected areas does not often take into serious account the needs of resource exploitation by the local populations or the conservation needs of these areas. We described the ecological characteristics and management issues affecting the buffer zone around the Fazao-Malfakassa National Park; a 192,000-ha protected area in central-western Togo of utmost conservation importance within the Dahomey Gap region. Within the buffer zone (10 km radius, 334,800 ha), we focussed on four high conservation value areas totalling 65,594 ha (20% of the total buffer zone area). Using 2015 sentinel-2 images we analyzed land cover patterns and described existing ecological zones. We complemented these with field surveys and interviews with 300 people living in 22 villages within the buffer zone to describe the conditions affecting the resident human population. Although over 60% of the total buffer zone area is degraded, we identified four areas of high conservation value (total area = 65,594 ha). Interviewees recognized that slash-and-burn was the most common form of land use, followed by agroforestry practices. Agriculture, charcoal, and firewood production were the main drivers affecting habitats, and land conflicts were recurrent due to the rise in human population. The decline in agriculture, reported by interviewees in some sectors, was attributable to ravages of crops by elephants. Three independent diversity indices showed that, in preserved zones, a greater diversity of animals (with similar utilization frequencies) were hunted than in degraded sites (where grasscutters were the dominant hunted species). There were also significant differences between degraded and preserved zones in terms of plants used for charcoal production and for non-timber forest products. We advocate the development of community-controlled hunting areas to enhance the conservation value of the four well-preserved zones. Instead, promoting sustainable agricultural production systems in the degraded areas can help to further stabilize the agricultural front and reduce land pressure on the park

Diagnosis of Bacterial Bloodstream Infections: A 16S Metagenomics Approach

YesBackground. Bacterial bloodstream infection (bBSI) is one of the leading causes of death in critically ill patients and accurate diagnosis is therefore crucial. We here report a 16S metagenomics approach for diagnosing and understanding bBSI. Methodology/Principal Findings. The proof-of-concept was delivered in 75 children (median age 15 months) with severe febrile illness in Burkina Faso. Standard blood culture and malaria testing were conducted at the time of hospital admission. 16S metagenomics testing was done retrospectively and in duplicate on the blood of all patients. Total DNA was extracted from the blood and the V3–V4 regions of the bacterial 16S rRNA genes were amplified by PCR and deep sequenced on an Illumina MiSeq sequencer. Paired reads were curated, taxonomically labeled, and filtered. Blood culture diagnosed bBSI in 12 patients, but this number increased to 22 patients when combining blood culture and 16S metagenomics results. In addition to superior sensitivity compared to standard blood culture, 16S metagenomics revealed important novel insights into the nature of bBSI. Patients with acute malaria or recovering from malaria had a 7-fold higher risk of presenting polymicrobial bloodstream infections compared to patients with no recent malaria diagnosis (p-value = 0.046). Malaria is known to affect epithelial gut function and may thus facilitate bacterial translocation from the intestinal lumen to the blood. Importantly, patients with such polymicrobial blood infections showed a 9-fold higher risk factor for not surviving their febrile illness (p-value = 0.030). Conclusions/Significance. Our data demonstrate that 16S metagenomics is a powerful approach for the diagnosis and understanding of bBSI. This proof-of-concept study also showed that appropriate control samples are crucial to detect background signals due to environmental contamination.This work was supported by the Flemish Ministry of Sciences (EWI, SOFI project IDIS).This paper has been subject to a correction. Please see Correction file above

A genomic appraisal of invasive Salmonella Typhimurium and associated antibiotic resistance in sub-Saharan Africa

Invasive non-typhoidal Salmonella (iNTS) disease manifesting as bloodstream infection with high mortality is responsible for a huge public health burden in sub-Saharan Africa. Salmonella enterica serovar Typhimurium (S. Typhimurium) is the main cause of iNTS disease in Africa. By analysing whole genome sequence data from 1303 S. Typhimurium isolates originating from 19 African countries and isolated between 1979 and 2017, here we show a thorough scaled appraisal of the population structure of iNTS disease caused by S. Typhimurium across many of Africa’s most impacted countries. At least six invasive S. Typhimurium clades have already emerged, with ST313 lineage 2 or ST313-L2 driving the current pandemic. ST313-L2 likely emerged in the Democratic Republic of Congo around 1980 and further spread in the mid 1990s. We observed plasmid-borne as well as chromosomally encoded fluoroquinolone resistance underlying emergences of extensive-drug and pan-drug resistance. Our work provides an overview of the evolution of invasive S. Typhimurium disease, and can be exploited to target control measures