Evidence map›Paper›PMID 42768361›Full record

ArticleGenome medicine2026

Migration and tuberculosis transmission in Hamburg, Germany: insights from 25 years of molecular epidemiology.

Nicole Ullrich, Roland Diel, Karen Meywald-Walter, Christian Schwarzbach, Matthias I Gröschel, Martin Kuhns, Inna Friesen, Stefan Niemann, Viola Dreyer

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Article in Genome medicine, 2026. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Not yet cited in PubMed.

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1 · What the graph read from it

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3 · Its place in the literature

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4 · The record

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5 · Who and what money

Authors and funding

9 authors.

Nicole UllrichResearch Center Borstel, Leibniz Lung Center, Molecular and Experimental Mycobacteriology, Borstel, Germany.
Roland DielInstitute for Epidemiology, University Medical Hospital Schleswig-Holstein, Kiel, Germany.
Karen Meywald-WalterPublic Health Department Hamburg-Mitte, Hamburg, Germany.
Christian SchwarzbachPublic Health Department Hamburg-Mitte, Hamburg, Germany.
Matthias I GröschelResearch Center Borstel, Leibniz Lung Center, Molecular and Experimental Mycobacteriology, Borstel, Germany.
Martin KuhnsResearch Center Borstel, Leibniz Lung Center, National and Supranational Reference Center for Mycobacteria, Borstel, Germany.
Inna FriesenResearch Center Borstel, Leibniz Lung Center, National and Supranational Reference Center for Mycobacteria, Borstel, Germany.
Stefan Niemann *Research Center Borstel, Leibniz Lung Center, Molecular and Experimental Mycobacteriology, Borstel, Germany.
Viola Dreyer *Research Center Borstel, Leibniz Lung Center, Molecular and Experimental Mycobacteriology, Borstel, Germany. vdreyer@fz-borstel.de.ORCID http://orcid.org/0000-0003-2997-3693

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

backgroundTuberculosis (TB) epidemiology in low-incidence settings is increasingly influenced by the importation of Mycobacterium tuberculosis complex (Mtbc) strains from high-incidence regions. Globally, more virulent "generalist" lineages such as Lineage 2 (L2) and Lineage 4 (L4) contrast with geographically restricted "specialist" lineages (L1, L3, L5-L9), reflecting differences in transmissibility and adaptation. The introduction of strains of diverse lineages can alter local transmission dynamics and drug susceptibility patterns, underscoring the need for high-resolution genomic surveillance.

methodsWe performed whole genome sequencing (WGS) on 3,131 Mtbc strains collected from patients with TB in Hamburg, Germany, over 25 years (1997-2021). We analysed population structure and transmission dynamics in relation to patients' self-reported geographical origins.

resultsStrains from major Mtbc lineages L1-L6 and M. bovis were detected, with L4 strains being most prevalent (74.6%, n = 2,337). Lineage distribution shifted over time: L4 strains decreased from 83.5% in the first five years to 63.0% in the last five years, while L3 strains increased from 4.8% to 18.1%. These changes correlated with an increasing number of foreign-born patients rather than enhanced transmission of strains of specific lineages. L4 strains accounted for most clusters (81%, 218/269). In-depth analyses revealed heterogeneity in transmission potential among L4 sublineages, underscoring the importance of sublineage-level resolution. Strains of sublineages L4.1.2.1, L4.8, and L4.3 were detected in patients born in over 15 regions each, with >57% of cases from Europe, supporting their representation as globally successful generalist lineages.

conclusionsMigration substantially increased the genetic diversity of the Mtbc population in Hamburg but did not fundamentally alter local transmission dynamics. Transmission remained lineage-specific and was predominantly driven by established L4 strains, suggesting that successful transmission is mediated by locally adapted sublineages. Predominant L4.1.2.1 and L4.8 sublineages occurred in individuals from a wide range of countries, supporting the generalist-specialist hypothesis at the sublineage level. These findings highlight the interplay between pathogen characteristics and host demographics in shaping transmission and the value of integrating genomic, demographic, and epidemiological data to distinguish imported cases from sustained local transmission in low-incidence settings.

Indexed as

Mycobacterium tuberculosisTuberculosisGermanyHumansMolecular EpidemiologyPhylogenyWhole Genome SequencingHost-adaptationMigrationTuberculosis

Identifiers

PMID42768361
PMCPMC13595784

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