Modeling and optimization of compaction pressure, binder percentage and retention time in the production process of carbonized sawdust-based biofuel briquettes using response surface methodology (RSM).

The importance of parameters such as compaction pressure, binder percentage and retention time and their interaction in the production of carbonized briquettes for domestic or industrial use cannot be overestimated, as they have a considerable impact on the properties of the resulting briquettes. This study used Box-Behnken Response Surface Methodology (RSM) and Analysis Of Variance (ANOVA) to show how the above parameters and their interactions significantly influence the Higher Heating Value (HHV), ash content and Impact Resistance Index (IRI) of the biofuels obtained. The briquettes are characterized in accordance with American Society for Testing and Materials ASTM D-(5865 and 3172). IRI is determined by the drop test. The Niton XLT900s X-ray fluorescence spectrometer is used for mineralogical analysis. The peel starch used as a binder is characterized by the Association of Official Agricultural Chemists standard. This starch has a starch purity of 89.8 %, an HHV of 13974 kJ/kg, a protein content of 4.79 % and a sugar content of 1.3 %. The HHV of the biofuels ranged from 23783 to 26050 kJ/kg, their ash content from 2.86 to 5.24 %, and the IRI from 136.36 to 500 %. The significant effect of binder on these results is confirmed (p < 0.05). The Standard deviations of ± 21.425 kJ/kg, ± 0.021 % and ± 2.121 % were obtained between the experimental values and those of the mathematical models developed to predict HHV, ash content and IRI. The optimum parameters for industrial biofuel production correspond to a binder percentage of 10 %, a compaction pressure of 75 kPa and a retention time of 7.49 min. The experimental results under these conditions are: 25596 kJ/kg, 3.01 % and 375 % for HHV, ash content and IRI. In correlation with the absence of certain heavy metals, the study confirms that the briquettes produced are suitable for domestic use.

Detection of a cluster of Omicron's BA.4 sublineage in Northern Senegal and identification of the first XAS recombinant variant in Senegal.

In Senegal, since its first detection in early March 2020, genomic surveillance of SARS-CoV-2 isolates has led to the identification of the emergence of the Omicron BA.4 and BA.5 sublineages from early June 2022. To investigate the origin of a cluster of cases in Northern Senegal on July 2022, isolates were analysed using Next-generation sequencing and phylogeny. Our data provided evidence of the origin of the cluster of BA.4 cases from a XAS recombinant, that is to date, the first reported sequence of this variant from Senegal. Continuous genomic surveillance of positive SARS-CoV-2 samples is a crucial need.

Uncertainty Quantification for Epidemic Risk Management: Case of SARS-CoV-2 in Morocco.

In this paper, we propose a new method for epidemic risk modelling and prediction, based on uncertainty quantification (UQ) approaches. In UQ, we consider the state variables as members of a convenient separable Hilbert space, and we look for their representation in finite dimensional subspaces generated by truncations of a suitable Hilbert basis. The coefficients of the finite expansion can be determined by approaches established in the literature, adapted to the determination of the probability distribution of epidemic risk variables. Here, we consider two approaches: collocation (COL) and moment matching (MM). Both are applied to the case of SARS-CoV-2 in Morocco, as an epidemic risk example. For all the epidemic risk indicators computed in this study (number of detections, number of deaths, number of new cases, predictions and human impact probabilities), the proposed models were able to estimate the values of the state variables with precision, i.e., with very low root mean square errors (RMSE) between predicted values and observed ones. Finally, the proposed approaches are used to generate a decision-making tool for future epidemic risk management, or, more generally, a quantitative disaster management approach in the humanitarian supply chain.

Surveillance of Viral Encephalitis in the Context of COVID-19: A One-Year Observational Study among Hospitalized Patients in Dakar, Senegal.

The burden of encephalitis and its associated viral etiology is poorly described in Africa. Moreover, neurological manifestations of COVID-19 are increasingly reported in many countries, but less so in Africa. Our prospective study aimed to characterize the main viral etiologies of patients hospitalized for encephalitis in two hospitals in Dakar. From January to December 2021, all adult patients that met the inclusion criteria for clinical infectious encephalitis were enrolled. Cerebrospinal fluids, blood, and nasopharyngeal swabs were taken and tested for 27 viruses. During the study period, 122 patients were enrolled. Viral etiology was confirmed or probable in 27 patients (22.1%), with SARS-CoV-2 (n = 8), HSV-1 (n = 7), HHV-7 (n = 5), and EBV (n = 4) being the most detected viruses. Age groups 40-49 was more likely to be positive for at least one virus with an odds ratio of 7.7. The mortality was high among infected patients, with 11 (41%) deaths notified during hospitalization. Interestingly, SARS-CoV-2 was the most prevalent virus in hospitalized patients presenting with encephalitis. Our results reveal the crucial need to establish a country-wide surveillance of encephalitis in Senegal to estimate the burden of this disease in our population and implement strategies to improve care and reduce mortality.

Development and clinical validation of loop-mediated isothermal amplification (LAMP) assay to diagnose high HBV DNA levels in resource-limited settings.

OBJECTIVE: A massive scale-up of testing and treatment is indicated to globally eliminate hepatitis B virus (HBV) infection. However, access to a polymerase chain reaction (PCR), a key test to quantify HBV DNA levels and determine treatment eligibility, is limited in resource-limited countries. We have developed and evaluated the loop-mediated isothermal amplification (LAMP) assay to diagnose clinically important HBV DNA thresholds defined by the WHO (≥20 000 and ≥ 200 000 IU/mL). METHODS: Pan-genotypic primer sets were designed on conserved HBV gene regions. Accuracy of LAMP to identify highly viraemic patients was evaluated in 400 and 550 HBV-infected people in France and Senegal, respectively. RESULTS: Our primers successfully detected eight major HBV genotypes/sub-genotypes (A1/2/3/B/C/D/E/F) with a detection limit ranging between 40 and 400 IU/mL. In France, the area under the receiver operating characteristic curve (AUROC), sensitivity and specificity of bead-based extraction and real-time turbidimetric LAMP were 0.95 (95% CI 0.93-0.97), 91.1% and 86.0%, respectively, to diagnose HBV DNA ≥20 000 IU/mL; and 0.98 (0.97-0.99), 98.0% and 94.6% for ≥200 000 IU/mL. The performance did not vary by viral genotypes. In Senegal, using a field-adapted method (reagent-free boil-and-spin extraction and inexpensive end-point fluorescence detection), the AUROC, sensitivity and specificity were 0.95 (0.93-0.97), 98.7% and 91.5%, respectively, to diagnose HBV DNA ≥200 000 IU/mL. The assay was not adapted to discriminate low-level viraemia. DISCUSSION: We have developed a simple, rapid (60 min), and inexpensive (US$8/assay) alternative to PCR to diagnose high viraemia ≥200 000 IU/mL. HBV-LAMP may contribute to eliminating HBV mother-to-child transmission by identifying high-risk pregnant women eligible for antiviral prophylaxis in resource-limited countries.

The Effects of the Maternal Health Improvement Project in the Louga Region of Senegal.

Maternal mortality remains a major global health challenge in sub-Saharan Africa. Senegal is one of the countries in the region that lagged behind in reaching the Millennium Development Goal 5, the deadline of which passed in 2015. The objective of this study was to assess the effects of information, education, and communication (IEC) activities conducted in Louga, Senegal. Community groups and facilitators conducted IEC campaigns, home visits, and various awareness-raising activities. This study used secondary data as part of the baseline and mid-term evaluations. Participants included women and men who had one or more children under five years of age. It was found that the level of awareness of at least three danger signs of pregnancy recognised by men significantly increased, and husbands/partners more frequently accompanied their wives during antenatal care in 2019 than in 2018. Women's empowerment improved significantly in terms of women making their own health decisions, joining community decision-making associations or groups, and using contraception. This project indicates that policies and programs are needed to increase men's involvement and empower women to further women's reproductive health to achieve the Sustainable Development Goal 3 and reduce maternal mortality in Senegal.

Confirmed Case of Buruli Ulcer, Senegal, 2018.

Buruli ulcer is a necrotizing skin disease caused by Mycobacterium ulcerans and is usually associated with tropical climates and exposure to slow-moving or stagnant water. We report a case of Buruli ulcer that may have originated in an urban semiarid area of Senegal.

Poor Sensitivity of Commercial Rapid Diagnostic Tests for Hepatitis B e Antigen in Senegal, West Africa.

Limited access to nucleic acid tests for hepatitis B virus (HBV) DNA is a significant barrier to the effective management of chronic HBV infection in resource-poor countries. Alternatively, HBV e antigen (HBeAg) may accurately indicate high viral replication. We assessed the diagnostic performance of three commercially available rapid diagnostic tests (RDTs) for HBeAg (SD Bioline, Insight and OneStep) against a quantitative chemiluminescent immunoassay (CLIA, Architect). Using stored sera from adults with chronic HBV infection, we tested RDTs in three groups in Senegal (48 HBeAg-positive, 196 HBeAg-negative, and 117 cases with high HBV DNA (≥ 106 IU/mL)) and one group in France (17 HBeAg-positive East Asians). In Senegal, the sensitivity and specificity for HBeAg detection were 29.8% and 100% for SD Bioline, 31.1% and 100% for Insight, and 42.5% and 98.4% for OneStep, respectively. The lower limits of detection of these RDTs were very high (> 2.5 log10 Paul Ehrlich Institut units/mL). Their low sensitivity was also confirmed in HBeAg-positive Asian samples (35.3-52.9%). The prevalence of HBeAg in highly viremic (≥ 106 IU/mL) Senegalese patients was low: 58.1% using CLIA and 24.5-37.5% using RDTs. Hepatitis B e antigen prevalence was similarly low in a subgroup of 28 Senegalese women of childbearing age with a high viral load (≥ 106 IU/mL). Approximately, half of highly viremic adults do not carry HBeAg in Africa, and HBeAg RDTs had remarkably poor analytical and diagnostic sensitivity. This implies that HBeAg-based antenatal screening, particularly if using the currently available HBeAg RDTs, may overlook most pregnant women at high risk of mother-to-child transmission in Africa.