ABSTRACT
Tuberculosis disease stands for the second leading cause of death worldwide after COVID-19, most active tuberculosis cases result from the reactivation of latent TB infection through impairment of immune response. Several factors are known to sustain that process. Schistosoma mansoni, a parasite of the helminth genus that possesses switching power from an immune profile type Th1 to Th2 that favors reactivation of latent TB bacteria. The aim of the study was to assess the prevalence of the co-infection between the two endemic infections. Systematic literature was contacted at the University Clinical Research Center at the University of Sciences, Techniques, and Technologies of Bamako in Mali. Original articles were included, and full texts were reviewed to assess the prevalence and better understand the immunological changes that occur during the co-infection. In total, 3530 original articles were retrieved through database search, 53 were included in the qualitative analysis, and data from 10 were included in the meta-analysis. Prevalence of the co-infection ranged from 4% to 34% in the literature. Most of the articles reported that immunity against infection with helminth parasite and more specifically Schistosoma mansoni infection enhances latent TB reactivation through Th1/Th2. In sum, the impact of Schistosoma mansoni co-infection with Mycobacterium tuberculosis is under-investigated. Understanding the role of this endemic tropical parasite as a contributing factor to TB epidemiology and burden could help integrate its elimination as one of the strategies to achieve the END-TB objectives by the year 2035.
ABSTRACT
Background: Emergence of Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants may contribute to prolonging the pandemic and increasing morbidity, and mortality related to coronavirus disease 2019 (COVID-19). We describe the dynamics of circulating SARS-CoV-2 variants identified during the different COVID-19 waves that occurred in Mali between April 2021 and October 2021. Methods: We sequenced respiratory SARS-CoV-2 complete spike (S) gene from positive samples. Generated sequences were aligned by Variant Reporter v3.0 using Wuhan-1 strain as a reference. Mutations were noted using the GISAID and Nextclade platforms. Results: Of 16,797 nasopharyngeal swab samples tested, 6.0 % (1008/16,797) were RT-qPCR positive for SARS-CoV-2. Of these, 16.07% (162/1008) had a Ct value ≤ 28 and were amplified and sequenced. We recovered complete S-gene sequence from 80 of 162 [49.8%] samples. We identified seven distinct variants including Delta [62.5%], Alpha [1.2%], Beta [1.2%], Eta [30.0%], 20B [2.5%], 19B and 20A [1.2% each]. Conclusion and perspectives: Our results show the presence of several SARS-CoV-2 variants during COVID-19 waves in Mali between April and October 2021. The continued emergence of new variants highlights the need to strengthen local real-time sequencing capacity, and genomic surveillance for better and coordinated national responses to SARS-CoV-2.