Seroprevalence of Bas-Congo virus in Mangala, Democratic Republic of the Congo: a population-based cross-sectional study.

BACKGROUND: Bas-Congo virus (BASV), an emerging tibrovirus, was associated with an outbreak of acute haemorrhagic fever in Mangala, Democratic Republic of the Congo, in 2009. In 2012, neutralising antibodies to BASV were detected in the lone survivor and one of his close contacts. However, subsequent serological and molecular surveys were unsuccessful as neither BASV antibodies nor its RNA were detected. In this study, we determined the seroprevalence of BASV infection in Mangala 13 years after the initial outbreak. METHODS: We conducted a population-based serological survey from Jan 17 to Jan 23, 2022. Consenting individuals at least 5 years of age, living in Mangala for at least 4 weeks, and who had no contraindication to venepuncture were enrolled. Participants were interviewed using a pre-tested questionnaire for sociodemographic and clinical characteristics. We supplemented the collected serum samples with 284 archived samples from Matadi and Kinshasa. All samples were tested for antibodies to BASV and other tibroviruses using a pseudovirus-based neutralisation test. FINDINGS: Among the 267 individuals from Mangala, the prevalence of BASV antibodies was 55% (95% CI 49-61; n=147). BASV seropositivity odds significantly increased with age (5·2 [95% CI 2·1-12·9] to 83·9 [20·8-337·7] times higher in participants aged 20 years or older than participants aged 5-19 years). Some occupational categories (eg, farmer or public servant) were associated with seropositivity. Only nine (6%) of 160 samples from Matadi and one (<1%) of 124 samples from Kinshasa had neutralising antibodies to BASV. Moreover, we also detected neutralising antibodies to other tibroviruses-Ekpoma virus 1, Ekpoma virus 2, and Mundri virus-in 84 (31%), 251 (94%), and 219 (82%) of 267 Mangala samples; 14 (9%), 62 (39%), and 120 (75%) of 160 Matadi samples; and six (5%), five (4%), and 33 (27%) of 124 Kinshasa samples, respectively. INTERPRETATION: Human infection with BASV and other tibroviruses seems common in Mangala, although no deadly outbreak has been reported since 2009. Exposure to BASV might be highly restricted to Mangala and the increasing prevalence of neutralising antibodies with age suggests regular contact with the virus in this city. Altogether, our findings suggest that human infection with tibroviruses could be common in the study areas and not associated with deadly haemorrhagic or debilitating syndromes. FUNDING: Japan Agency for Medical Research and Development (AMED) and Japan International Cooperation Agency (JICA) under the Science and Technology Research Partnership for Sustainable Development (SATREPS) and Japan Program for Infectious Diseases Research and Infrastructure from AMED.

A multi-country phase 2 study to evaluate the suitcase lab for rapid detection of SARS-CoV-2 in seven Sub-Saharan African countries: Lessons from the field.

BACKGROUND: The COVID-19 pandemic led to severe health systems collapse, as well as logistics and supply delivery shortages across sectors. Delivery of PCR related healthcare supplies continue to be hindered. There is the need for a rapid and accessible SARS-CoV-2 molecular detection method in low resource settings. OBJECTIVES: To validate a novel isothermal amplification method for rapid detection of SARS-CoV-2 across seven sub-Sharan African countries. STUDY DESIGN: In this multi-country phase 2 diagnostic study, 3,231 clinical samples in seven African sites were tested with two reverse transcription Recombinase-Aided Amplification (RT-RAA) assays (based on SARS-CoV-2 Nucleocapsid (N) gene and RNA-dependent RNA polymerase (RdRP) gene). The test was performed in a mobile suitcase laboratory within 15 min. All results were compared to a real-time RT-PCR assay. Extraction kits based on silica gel or magnetic beads were applied. RESULTS: Four sites demonstrated good to excellent agreement, while three sites showed fair to moderate results. The RdRP gene assay exhibited an overall PPV of 0.92 and a NPV of 0.88. The N gene assay exhibited an overall PPV of 0.93 and a NPV 0.88. The sensitivity of both RT-RAA assays varied depending on the sample Ct values. When comparing sensitivity between sites, values differed considerably. For high viral load samples, the RT-RAA assay sensitivity ranges were between 60.5 and 100% (RdRP assay) and 25 and 98.6 (N assay). CONCLUSION: Overall, the RdRP based RT-RAA test showed the best assay accuracy. This study highlights the challenges of implementing rapid molecular assays in field conditions. Factors that are important for successful deployment across countries include the implementation of standardized operation procedures, in-person continuous training for staff, and enhanced quality control measures.

High Severe Acute Respiratory Syndrome Coronavirus 2 Antibody Prevalence After the Third Epidemic Wave (May-October 2021) in Matadi, Democratic Republic of the Congo.

Background: By the end of the third wave of the coronavirus disease 2019 (COVID-19) epidemic (May-October 2021), only 3130 of the 57 268 confirmed cases of coronavirus disease 2019 (COVID-19) in the Democratic Republic of the Congo (DRC) were reported in Kongo Central. This province, and especially its capital city, Matadi, has essential trade and exchanges with Kinshasa, the epicenter of the COVID-19 epidemic in DRC. Kinshasa accounted for 60.0% of all cases during the same period. The true burden of COVID-19 in Matadi is likely underestimated. In this study, we aimed to determine the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) seroprevalence and associated risk factors after the third wave in Matadi. Methods: We conducted a population-based cross-sectional study in October 2021. Consenting participants were interviewed and tested using an enzyme-linked immunosorbent assay commercial kit. We applied univariable and multivariable analysis to evaluate factors associated with seropositivity and adjusted the seroprevalence for the test kit performance. Results: We included 2210 participants from 489 households. Female participants represented 59.1%. The median age was 27 years (interquartile range, 16-45 years). The crude SARS-CoV-2 seroprevalence was 82.3%. Age was identified as the main risk factor as younger age decreased the seropositivity odds. Accounting for clustering at the household level increased the seroprevalence to 83.2%. The seroprevalence increased further to 88.1% (95% confidence interval, 86.2%-90.1%) after correcting for the laboratory test kit performance. Conclusions: The SARS-CoV-2 seroprevalence was very high, contrasting with reported cases. Evidence generated from this population-based survey remains relevant in guiding the local COVID-19 response, especially vaccination strategies.