Tuberculosis transmission and resistance among Ukrainian migrants and its impact on multidrug-resistant tuberculosis dynamics in high-influx host countries

BACKGROUND: The war in Ukraine triggered unprecedented migration into Central Europe, raising concerns regarding tuberculosis (TB) spread. METHODS: We conducted a molecular-epidemiological study including all Ukrainian migrants with culture-confirmed TB in Slovakia and the Czech Republic between September 2021 and December 2024 (n = 229), together with all other multidrug-resistant (MDR) TB cases reported in these countries between 2023 and 2024 (n = 28). Whole-genome sequencing (WGS) was performed on cultured Mycobacterium tuberculosis complex (MTBC) isolates, and the resulting data were used for phylogenetic reconstruction, lineage classification, genomic resistance prediction, and cluster analysis. FINDINGS: Since the war began in 2022, the share of TB cases from Ukrainian migrants in the Czech Republic rose significantly (P < 0.001), along with an evident increase in total MDR-TB cases. Out of 199 MTBC strains from Ukrainian migrants with good-quality WGS data, 129 (64.8%) were predicted to be susceptible, 25 MDR (12.6%), 8 pre-extensively drug-resistant (pre-XDR; 4%), and 37 (18.6%) had other resistance patterns including bedaquiline/clofazimine monoresistance. Among MDR/pre-XDR strains (n = 59) lineage 2 predominated (63.5%), mainly belonging to the Central Asia clades (45.0%) and the Europe/Russian W148 outbreak clone (52.9%), followed by lineage 4 (28.9%). Cluster analysis (5 allele threshold) identified 10 MDR/pre-XDR TB clusters, each with two isolates. Only one of those clusters included a Ukrainian migrant and non-Ukrainian patient from the host country. CONCLUSION: Migration increased both, the TB and MDR-TB burden especially in the Czech Republic. Transmission of imported MTBC strains from migrants to host populations appears to be limited, but needs to be closely monitered prospectively.