Evaluation of antigen-based rapid detection test for the diagnosis of SARS CoV-2 in low-income countries.

BACKGROUND: In the context of the Covid-19 pandemic and following the increasing number of suspicious Covid-19 cases in Madagascar, Malagasy laboratories are overflowed mainly due to lack of human resource and available material restriction. The development and validation of rapid and easy-to-perform diagnostic methods are worth of interest and high priority. The aim of this prospective study was to evaluate the performances of a rapid immunochromatographic test for the detection of SARS-CoV-2 antigen, in comparison to Reverse transcription polymerase chain reaction (RT-PCR). METHODS: The fluorescence immunochromatographic SARS-CoV-2 antigen test StandardTM Q COVID-19 Ag Test (SD Biosensor Republic Korea) was evaluated in samples derived from patients who were examined for disease categories. Diagnostic accuracy was determined in comparison to SARS-CoV-2 RT-PCR considered as gold standard. RESULTS: A total of 200 samples were included; 94 were RT-PCR positive. Median patients' age was 38.36 years, 63.5 % were male. Overall sensitivity and specificity of the Standard TM Q COVID-19 Ag (SD Biosensor® Republic Korea) were 62.66 % and 100 %, the sensitivity was significantly higher (100 %) in samples with high viral loads (Ct<29). CONCLUSIONS: This antigen-based immunofluorescence RDT could be the potential to become an important tool for the early diagnosis of SARS-CoV-2 particularly in situations with limited access to molecular methods particularly in rural area of Madagascar.

New insights into Human Pegivirus-1 (HPgV-1) genotypes diversity in sub-Saharan Africa.

In the framework of a viral discovery research program using metagenomics, Human Pegivirus-1 reads (HPgV-1, formerly known as GBV-C) were detected in plasma pools of healthy blood donors from seven sub-Saharan African countries. For five of these countries, Mauritania, Mali, Niger, Burundi and Madagascar, no data about HPgV-1 genotypes was reported to date. To confirm our metagenomic findings and further investigate the genotype diversity and distribution of HPgV-1 in Africa, 400 blood donations from these five localities as well as from Cameroon, the Democratic Republic of Congo (DRC) and the Burkina Faso were screened with a RT-nested PCR targeting the viral 5'NCR region. Amplified products were sequenced, and the virus was genotyped by phylogenetic analysis. Out of the 400 plasma samples tested, 65 were positive for HPgV-1 RNA and 61 were successfully genotyped. Among these, 54 strains (88.5%) clustered with genotype 1, six (9.8%) with genotype 2 and one (1.6%) with genotype 5. Genotype 1 was observed in all countries studied, except in Madagascar, genotype 2 was detected in Mauritania and Madagascar, and genotype 5 in DRC. Overall, our results extend the geographic distribution of HPgV-1 in Africa and provide six additional nearly complete genomes. Considering that some HPgV-1 genotypes have been reported as potential predictive indicators of lower disease progression in HIV-1 infected subjects, further investigations should be conducted to better understand the positive impact, if any, of this virus.

High rate of hepatitis C virus and human immunodeficiency virus false-positive results in serologic screening in sub-Saharan Africa: adverse impact on the blood supply.

BACKGROUND: False positivity in blood screening may cause unnecessary deferral of healthy donors and exacerbate blood shortages. An international multicenter study was conducted to estimate the frequency of HCV and HIV false seropositivity in seven African countries (Burundi, Cameroon, Democratic Republic of Congo, Madagascar, Mali, Mauritania, and Niger). STUDY DESIGN AND METHODS: Blood donations were tested for hepatitis C virus (HCV) and human immunodeficiency virus (HIV) with rapid detection tests (RDTs), third-generation enzyme immunoassays (EIAs), or fourth-generation EIAs. HCV (456/16,613 [2.74%]) and HIV (249/16,675 [1.49%]) reactive samples were then confirmed with antigen/antibody assays, immunoblots, and nucleic acid testing. Partial viral sequences were analyzed when possible. RESULTS: The HCV reactivity rate with RDTs was significantly lower than with EIAs (0.55% vs. 3.52%; p < 0.0001). The HIV reactivity rate with RDTs was lower than with third-generation EIAs (1.02% vs. 2.38%; p < 0.0001) but similar to a fourth-generation assay (1.09%). Only 16.0% (57/357) and 21.5% (38/177) of HCV and HIV initial reactive samples, respectively, were repeatedly reactive. HCV and HIV infections were confirmed in 13.2% and 13.7%, respectively, of repeated reactive donations. The predominant HCV genotype 2 and 4 strains in West and Central Africa showed high genetic variability. HIV-1 subtype CRF02_AG was most prevalent. CONCLUSION: High rates (>80%) of unconfirmed anti-HCV and anti-HIV reactivity observed in several sub-Saharan countries highlights the need for better testing and confirmatory strategies for donors screening in Africa. Without confirmatory testing, HCV and HIV prevalence in African blood donors has probably been overestimated.

Evaluation of methicillin-resistant Staphylococcus aureus nasal carriage in Malagasy patients.

INTRODUCTION: Methicillin-resistant Staphylococcus aureus (MRSA) is an important cause of infections. It is well recognized that nasal carriage of S. aureus represents a potent and increasingly prevalent risk factor for subsequent S. aureus infection. However, in Madagascar no data exist concerning this nasal carriage of S. aureus. METHODOLOGY: Nasal swabs from 304 different patients attending the Laboratory of Training and Research in Medical Biology of Madagascar were cultured for methicillin sensitive (MSSA) and MRSA. RESULTS: One hundred and sixteen patients had S. aureus in their noses (38.16 ± 5.46%) of whom 45 (14.80 ± 3.99%) had MRSA.  A risk factor for MSSA nasal carriage included a history of hospitalization when antibiotics were administered (odds ratio [OR] 2.25, 1.09 - 4.64). Among MRSA nasal isolates, high rate of resistance to other antibiotics was observed, particularly for trimethoprim-sulfamethoxazole (68.89%), erythromycin (66.67%) and ofloxacin (53.33%). CONCLUSIONS: Our data showed a high rate of MRSA nasal carriage and a high rate of multidrug resistance. A strategic policy against the spread of multidrug resistant strains is desirable.