A model of COVID-19 pandemic evolution in African countries

We studied the COVID-19 pandemic evolution in selected African countries. For each country considered, we modeled simultaneously the data of the active, recovered and death cases. In this study, we used a year of data since the first cases were reported. We estimated the time-dependent basic reproduction numbers, $R_0$, and the fractions of infected but unaffected populations, to offer insights into containment and vaccine strategies in African countries. We found that $R_0\leq 4$ at the start of the pandemic but has since fallen to $R_0 \sim 1$. The unaffected fractions of the populations studied vary between $1-10$\% of the recovered cases.Comment: 27 pages, 9 figures and 1 tabl

Antibacterial activities of selected edible plants extracts against multidrug-resistant Gram-negative bacteria

BACKGROUND: In response to the propagation of bacteria resistant to many antibiotics also called multi-drug resistant (MDR) bacteria, the discovery of new and more efficient antibacterial agents is primordial. The present study was aimed at evaluating the antibacterial activities of seven Cameroonian dietary plants (Adansonia digitata, Aframomum alboviolaceum, Aframomum polyanthum, Anonidium. mannii, Hibiscus sabdarifa, Ocimum gratissimum and Tamarindus indica). METHODS: The phytochemical screening of the studied extracts was performed using described methods whilst the liquid broth micro dilution was used for all antimicrobial assays against 27 Gram-negative bacteria. RESULTS: The results of the phytochemical tests indicate that all tested extracts contained phenols and triterpenes, other classes of chemicals being selectively present. The studied extracts displayed various degrees of antibacterial activities. The extracts of A. digitata, H. sabdarifa, A. polyanthum, A. alboviolaceum and O. gratissimum showed the best spectra of activity, their inhibitory effects being recorded against 81.48%, 66.66%, 62.96%, 55.55%, and 55.55% of the 27 tested bacteria respectively. The extract of A. polyanthum was very active against E. aerogenes EA294 with the lowest recorded minimal inhibitory concentration (MIC) of 32 μg/ml. CONCLUSION: The results of the present work provide useful baseline information for the potential use of the studied edible plants in the fight against both sensitive and MDR phenotypes

A community effort towards a knowledge-base and mathematical model of the human pathogen Salmonella Typhimurium LT2

<p>Abstract</p> <p>Background</p> <p>Metabolic reconstructions (MRs) are common denominators in systems biology and represent biochemical, genetic, and genomic (BiGG) knowledge-bases for target organisms by capturing currently available information in a consistent, structured manner. <it>Salmonella enterica </it>subspecies I serovar Typhimurium is a human pathogen, causes various diseases and its increasing antibiotic resistance poses a public health problem.</p> <p>Results</p> <p>Here, we describe a community-driven effort, in which more than 20 experts in <it>S</it>. Typhimurium biology and systems biology collaborated to reconcile and expand the <it>S</it>. Typhimurium BiGG knowledge-base. The consensus MR was obtained starting from two independently developed MRs for <it>S</it>. Typhimurium. Key results of this reconstruction jamboree include i) development and implementation of a community-based workflow for MR annotation and reconciliation; ii) incorporation of thermodynamic information; and iii) use of the consensus MR to identify potential multi-target drug therapy approaches.</p> <p>Conclusion</p> <p>Taken together, with the growing number of parallel MRs a structured, community-driven approach will be necessary to maximize quality while increasing adoption of MRs in experimental design and interpretation.</p

Contaminants in Foods of Animal Origin in Cameroon: A One Health Vision for Risk Management “from Farm to Fork”

Foods of animal origin represent an important share in the diet of Cameroonian populations. Cameroon is known to be a food basket in the west and central Africa sub-region, and an important supplier of foods on the international markets. In the meantime, food importation is continuously increasing to meet the high demand of a more westernized segment of the population. Cereals, fish, sea products, eggs, honey, shrimps, chicken, and feed ingredients are important share in the international trade of agricultural products. Few controls are made on the quality and safety of these products. Certain safety standards do exist but are still yet to be enforced. Inspections done so far by regulatory authorities are partial and do not cover important hazards that require laboratory analysis. The increasing awareness of population, the burden of new types of disease, as well as the recurrence of food scandals have recently launched a scientific and population debate on the contribution of foods items, especially those of animal origin, to the toxic exposure of food producing animals and humans. This paper critically reviews the occurrence of toxicants in most consumed foods of animal origin in Cameroon. This study included the most consumed food of animal origin, identified during the national household budget survey and contributing to 8.1% of the total diet of an individual. Data evaluated suggest an important contamination by toxic metals, mycotoxins, veterinary drugs’ residues, and pesticides. The current national legal framework is briefly analyzed to explore possible intervention measures in the frame of the One Health approach

Clayey soils from Boulgou (North Cameroon): geotechnical, mineralogical, chemical characteristics and properties of their fired products

peer reviewedIn this study, clayey soils are characterized as backfill and potential fusible raw materials for engineering. Geotechnical tests (particle size distribution, Atterberg limits, densities) and chemico-mineralogical analyses (X-ray fluorescence, X-ray diffraction and Fourier transform infrared) were carried out on samples collected from field in the locality of Boulgou (North Cameroon) followed by the determination of mechanical properties of fired bricks (850–1200 °C). The excavations carried out have revealed a thick layer of clayey soils (~ 2 to 2.5 m) over a sandy layer. This clay formation presents some stratifications with limited influence variation in terms of mineralogy. Mean grain size distribution is dominated by sand (62–80%), clay (12–25%) and silt (6–9%). It corresponds to silty–clayey soils regarding their methylene blue values (3.3–5.6), with low plastic (13–22%) to high plastic (33%) characteristics. They are classified by USCS as clayey sand/silty clay, while one sample is a poorly graded sand (SP). Clay minerals observed are kaolinite (6–12%), montmorillonite (2–6%) and illite (8–10%). Those parameters associated with their fine nature and high compressibility make them suitable engineering applications for backfill material and barriers. From chemical analyses, relatively high contents in alkali and alkaline earth elements (~ 4 to 6%) to be used as potential fusible raw materials for fired bricks or gres ceramics were revealed. Bricks characteristics are varied: linear shrinkage (0.3 to 9%), bulk density (1.8 to 2.3 g/cm3), water absorption (19.7 to 1.3%) and flexural strength (0.3 to 17.4 MPa). Overall, the requirement for fired brick (< 20%) is met up by the water absorption values. As from 1050 °C, these soils are made suitable for brick-making with good characteristics (metallic sound, good cohesion and flexural strength)

Antibacterial and antibiotic-potentiation activities of the methanol extract of some cameroonian spices against Gram-negative multi-drug resistant phenotypes

<p>Abstract</p> <p>Background</p> <p>The present work was designed to evaluate the antibacterial properties of the methanol extracts of eleven selected Cameroonian spices on multi-drug resistant bacteria (MDR), and their ability to potentiate the effect of some common antibiotics used in therapy.</p> <p>Results</p> <p>The extract of <it>Cinnamomum zeylanicum</it> against <it>Escherichia coli</it> ATCC 8739 and AG100 strains showed the best activities, with the lowest minimal inhibitory concentration (MIC) of 64 μg/ml. The extract of <it>Dorstenia psilurus</it> was the most active when tested in the presence of an efflux pump inhibitor, phenylalanine Arginine<it>-β-</it> Naphtylamide (PAβN), a synergistic effect being observed in 56.25 % of the tested bacteria when it was combined with Erythromycin (ERY).</p> <p>Conclusion</p> <p>The present work evidently provides information on the role of some Cameroonian spices in the fight against multi-resistant bacteria.</p

Activities of selected medicinal plants against multi-drug resistant Gram-negative bacteria in Cameroon

Background: Medicinal plants are used worldwide for several human ailments including bacterial infections. The present work was designed to assess the in vitro antibacterial activities of some Cameroonian medicinal plants including Entada abyssinica , Entada africana , Pentaclethra macrophylla , Allexis cauliflora , Anthocleista leibrechtsiana , Carapa procera , Carica papaya and Persea americana against Gram-negative bacteria expressing multidrug resistant (MDR) phenotypes. Methods: The microbroth dilution was used to determine the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of the samples against eight bacterial strains belonging to four species, Escherichia coli , Enterobacter aerogenes , Klebsiella pneumoniae and Providencia stuartii . Results: The extracts displayed selective antibacterial activities with the minimal inhibitory concentrations (MIC) values ranges of 64 to 1024 μg/mL. The most active extract was that from Pentaclethra macrophylla (TPM) that showed inhibitory activities against five of the eight (62.5%) tested bacteria. The lowest MIC value (64 μg/mL) was recorded with the crude extract of Entada africana against E. coli AG100A whilst the best MBC (256 μg/mL) value was also obtained with methanol extract of Persea americana against this bacterial strain. Conclusion: The results of the present work provide baseline information on the possible use of Pentaclethra macrophylla, Entada africana and Entada abyssinica in the treatment of selected bacterial infections