1) Background: Rapid and acurate diagnostic testing for case identification, quarantine, and contact tracing is essential for managing the COVID 19 pandemic. Rapid antigen detection tests are available, however, it is...1) Background: Rapid and acurate diagnostic testing for case identification, quarantine, and contact tracing is essential for managing the COVID 19 pandemic. Rapid antigen detection tests are available, however, it is important to evaluate their performances before use. We tested a rapid antigen detection of SARS-CoV-2, based on the immunochromatography (Boson Biotech SARS-CoV-2 Ag Test (Xiamen Boson Biotech Co., Ltd., China)) and the results were compared with the real time reverse transcriptase-Polymerase chain reaction (RT-PCR) (Gold standard) results;2) Methods: From November 2021 to December 2021, samples were collected from symptomatic patients and asymptomatic individuals referred for testing in a hospital during the second pandemic wave in Gabon. All these participants attending “CTA Angondjé”, a field hospital set up as part of the management of COVID-19 in Gabon. Two nasopharyngeal swabs were collected in all the patients, one for Ag test and the other for RT-PCR;3) Results: A total of 300 samples were collected from 189 symptomatic and 111 asymptomatic individuals. The sensitivity and specificity of the antigen test were 82.5% [95%CI 73.8 - 89.3] and 97.9 % [95%CI 92.2 - 98.2] respectively, and the diagnostic accuracy was 84.4% (95% CI: 79.8 - 88.3%). The antigen test was more likely to be positive for samples with RT-PCR Ct values ≤ 32, with a sensitivity of 89.8%;4) Conclusions: The Boson Biotech SARS-CoV-2 Ag Test has good sensitivity and can detect SARS-CoV-2 infection, especially among symptomatic individuals with low viral load. This test could be incorporated into efficient testing algorithms as an alternative to PCR to decrease diagnostic delays and curb viral transmission.展开更多
In south-west Niger, ecosystems are losing several hectares of their surface area every year due to internally displaced persons and refugees. The commune of Gothèye is not immune to this situation. The aim of th...In south-west Niger, ecosystems are losing several hectares of their surface area every year due to internally displaced persons and refugees. The commune of Gothèye is not immune to this situation. The aim of this research is to assess the impact of displaced persons and refugees on socio-spatio-temporal dynamics of ecosystems using Landsat images. To achieve this, Landsat TM, Landsat ETM+ and OLI 8 satellite images from September and March were used (2010 to 2024). Operations on Envi 5.3, field validation output and finally mapping on ArcGIS were the steps involved. Discrimination is significant, with kappa coefficients of 0.97, 0.96, 0.86 and 0.85. The results obtained indicate a degradation of natural ecosystems, reflected in a change in landscape structure, with a marked reduction in the quantity and quality of ecosystem goods. Analysis of the evolution of land use showed that 31% of the land remained in its initial state (unchanged), 69% underwent modifications, and 11% was converted to cropland. Over these fourteen years, the study area has undergone changes in land use patterns, which have resulted in a modification of landscape structure, with a marked decline in the quantity and quality of ecosystem services.展开更多
文摘1) Background: Rapid and acurate diagnostic testing for case identification, quarantine, and contact tracing is essential for managing the COVID 19 pandemic. Rapid antigen detection tests are available, however, it is important to evaluate their performances before use. We tested a rapid antigen detection of SARS-CoV-2, based on the immunochromatography (Boson Biotech SARS-CoV-2 Ag Test (Xiamen Boson Biotech Co., Ltd., China)) and the results were compared with the real time reverse transcriptase-Polymerase chain reaction (RT-PCR) (Gold standard) results;2) Methods: From November 2021 to December 2021, samples were collected from symptomatic patients and asymptomatic individuals referred for testing in a hospital during the second pandemic wave in Gabon. All these participants attending “CTA Angondjé”, a field hospital set up as part of the management of COVID-19 in Gabon. Two nasopharyngeal swabs were collected in all the patients, one for Ag test and the other for RT-PCR;3) Results: A total of 300 samples were collected from 189 symptomatic and 111 asymptomatic individuals. The sensitivity and specificity of the antigen test were 82.5% [95%CI 73.8 - 89.3] and 97.9 % [95%CI 92.2 - 98.2] respectively, and the diagnostic accuracy was 84.4% (95% CI: 79.8 - 88.3%). The antigen test was more likely to be positive for samples with RT-PCR Ct values ≤ 32, with a sensitivity of 89.8%;4) Conclusions: The Boson Biotech SARS-CoV-2 Ag Test has good sensitivity and can detect SARS-CoV-2 infection, especially among symptomatic individuals with low viral load. This test could be incorporated into efficient testing algorithms as an alternative to PCR to decrease diagnostic delays and curb viral transmission.
文摘In south-west Niger, ecosystems are losing several hectares of their surface area every year due to internally displaced persons and refugees. The commune of Gothèye is not immune to this situation. The aim of this research is to assess the impact of displaced persons and refugees on socio-spatio-temporal dynamics of ecosystems using Landsat images. To achieve this, Landsat TM, Landsat ETM+ and OLI 8 satellite images from September and March were used (2010 to 2024). Operations on Envi 5.3, field validation output and finally mapping on ArcGIS were the steps involved. Discrimination is significant, with kappa coefficients of 0.97, 0.96, 0.86 and 0.85. The results obtained indicate a degradation of natural ecosystems, reflected in a change in landscape structure, with a marked reduction in the quantity and quality of ecosystem goods. Analysis of the evolution of land use showed that 31% of the land remained in its initial state (unchanged), 69% underwent modifications, and 11% was converted to cropland. Over these fourteen years, the study area has undergone changes in land use patterns, which have resulted in a modification of landscape structure, with a marked decline in the quantity and quality of ecosystem services.
