Prevalence of COVID-19 at the Wahgnion-Gold mining site in Burkina Faso and use of RT-PCR initial cycle threshold to monitor the dynamics of SARS-CoV-2 load

+1Cissé, A., +*1,2Lingani, M., 1Tao, M., 1Nana, S., 1Kaboré, B., 3Eric D. A. S., 4Nassouri, A., 1Diagbouga, S., 5Bamba, S., and 1Tarnagda, Z.

1National Influenza Reference Laboratory, Unité des Maladies à Potentiel Epidémique, Maladies Émergentes et

Zoonoses, Institut de Recherche en Sciences de la Santé, Burkina Faso

2Unité de Recherche Clinique de Nanoro, Institut de Recherche en Sciences de la Santé, Nanoro, Burkina Faso

3Teranga Gold Corporation, Ouagadougou, Burkina Faso

4Wahgnion Gold Operation, Ouagadougou, Burkina Faso

5Institut Supérieur des Sciences de la Santé, Université Nazi BONI, Bobo-Dioulasso, Burkina Faso

*Correspondence to:; +joint first authors



 Background: To control the spread of coronavirus disease-19 (COVID-19) caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), it is necessary to adequately identify and isolate infectious patients particularly at the work place. Real time polymerase chain reaction (RT-PCR) assay is the recommended confirmatory method for the diagnosis of SARS-CoV-2 infection. The aim of this study was to determine the prevalence of SARSCoV-2 infection in Burkina Faso and to use the initial cycle threshold (Ct) values of RT-PCR as a tool to monitor the dynamics of the viral load.

Methodology: Between September 2021 and February 2022, oropharyngeal and/or nasopharyngeal swab samples of consecutively selected COVID-19 symptomatic and apparently healthy workers from the Wahgnion mining site in the South-western Burkina Faso who consented to the study were collected according to the two weeks shift program and tested for SARS-CoV-2 using RT-PCR assay. Patients positive for the virus were followed-up weekly until tests were negative. Association of the initial RT-PCR Ct values with disease duration was assessed by adjusted linear regression approach. Two-sided p value < 0.05 was considered statistically significant.

Results: A total of 1506 (92.9% males) participants were recruited into the study, with mean age and age range of 37.18.7 and 18-68 years respectively. The overall prevalence of SARS-CoV-2 infection was 14.3% (216/1506). Of the 82 patients included in the follow-up study, the longest duration of positive RT-PCR test, from the first positive to the first of the two negative RT-PCR tests, was 33 days (mean 11.6 days, median 10 days, interquartile range 814 days). The initial Ct values significantly correlated with the duration of RT-PCR positivity (with β=-0.54, standard error=0.09 for N gene, and β=-0.44, standard error=0.09 for ORF1ab gene, p<0.001). Participants with higher Ct values corresponding to lower viral loads had shorter viral clearance time than those of lower Ct values or higher viral loads.

Conclusion: Approximately 1 out of 7 tested miners had SARS-CoV-2 infection and the duration of their RT-PCR tests positivity independently correlated with the initial viral load measured by initial Ct values. As participants with lower initial Ct values tended to have longer disease duration, initial RT-PCR Ct values could be used to guide COVID-19 patient quarantine duration particularly at the work place.

 Keywords: SARS-CoV-2, COVID-19, RT-PCR, cycle threshold, prevalence, Burkina Faso

Received Aug 2, 2022; Revised Oct 5, 2022; Accepted Oct 9, 2022

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Prevalence of COVID-19 at the Wahgnion-Gold mining site in Burkina Faso and use of RT-PCR initial cycle threshold to monitor the dynamics of SARS-CoV-2 load