Import and transmission of Mycobacterium orygis and Mycobacterium africanum, Norway.

Background: The aim of the current study was to improve our understanding of the origins and transmission of Mycobacterium africanum (MAF) in Norway.

Methods: Whole-genome sequences (WGS) were generated for all (n = 29) available clinical isolates received at the Norwegian National Reference Laboratory for Mycobacteria (NRL) and identified as MAF in Norway, in the period 2010-2020. Phylogenetic analyses were performed.

Results: The analyses indicated several imports of MAF lineage 6 from both East and West African countries, whereas MAF lineage 5 was restricted to patients with West African connections. We also find evidence for transmission of MAF in Norway. Finally, our analyses revealed that a group of isolates from patients originating in South Asia, identified as MAF by means of a commercial line-probe assay, in fact belonged to Mycobacterium orygis.

Conclusions: Most MAF cases in Norway are the result of import, but transmission is occurring within Norway.