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6th Edition of World Congress on Infectious Diseases

June 24-26, 2024 | Paris, France

June 24 -26, 2024 | Paris, France
Infection 2024

Jiahui Zhu

Speaker at Infection Conference - Jiahui Zhu
University of Helsinki, Finland
Title : Transmission of drug-resistant mycobacterium tuberculosis isolates between Finnish- and foreign-born cases, 2014-2021: A molecular epidemiological study


Background: Data on the molecular epidemiological characteristics and transmission of drug-resistant Mycobacterium tuberculosis (MTB) in low-incidence settings with immigration from high-incidence settings is limited.

Method: We included 115 drug-resistant (DR) MTB isolates with whole-genome sequencing data isolated in Finland between 2014 and 2021. Potential transmission clusters were identified using a threshold of 12 single-nucleotide polymorphisms (SNPs). Highly related clusters were identified using a threshold of 5 SNPs.

Result: Of the 115 DR MTB isolates, 31 (27.0%) isolates were from Finnish-born cases and 84 (73.0%) were from foreign-born cases. The proportion of multidrug-resistant (MDR) MTB isolates (30/84, 35.7%) from foreign-born cases was higher than that of MDR MTB isolates from Finnish-born cases (8/31, 25.8%). The 115 DR MTB isolates were classified into four lineages, including lineage 1/Indo-Oceanic, lineage 2/East-Asian, lineage 3/East-African-Indian, and lineage 4/Euro-American. The lineage 2 (40/115, 34.8%) and lineage 4 (40/115, 34.8%) were prevalent lineages. The lineage diversity of DR MTB isolates was significantly different by regions of birth. DR MTB isolates from Finnish-born cases were classified into four lineages, with a dominant lineage 4. Isolates from Asia-born cases were mainly lineage 1, while most isolates from eastern European-born and sub-Saharan African-born cases were lineage 2 and lineage 3/Delhi-CSA, respectively. A total of 25 (21.7%) isolates were classified into eight potential transmission clusters (≤12 SNPs). The largest potential transmission cluster included nine lineage 3 isolates from patients notified between 2017 and 2020 and all, except one with an unknown country of birth, originating from sub-Saharan Africa. Within this cluster, three isolates from Eritrean-born patients and one isolate from Ethiopian-born patient were highly related. Four clustered isolates were from Finnish born patients and three of them were closely related to foreign-born patient isolates and one was possibly related. Two MDR-TB clusters were found, both consisted of two isolates of lineage 2 and 4, respectively, from foreign-born patients.

Conclusion: Transmission of drug-resistant MTB isolates between Finnish- and foreign-born persons is uncommon. Monitoring transmission dynamics of drug-resistant TB is of importance to inform tuberculosis management and control in low-incidence settings with increasing immigration.


Miss Zhu studied epidemiology of infectious disease at Fudan University, China and graduated as public health master in 2021. She then worked at Center for Disease Prevention and Control of Shanghai, China, until 2022. She works as a doctoral student at the research group of Prof. Tarja at Helsinki University, Finland, since 2023. She has published 6 research articles in SCI(E) journals.