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The presented work is the first epidemiological and molecular analysis of multidrug‑resistant (MDR) tuberculosis (TB) in Poland since the outbreak of the war in Ukraine. During the study period (2018–2022), significant changes were observed in the population of patients with drug‑resistant TB. The COVID‑19 pandemic seems to have reduced the incidence rates of this form of TB, while the war, through the influx of immigrants from beyond Poland’s eastern border, resulted in a dramatic increase in the number of registered cases. Our findings show that before 2022, a majority of MDR‑TB patients were Polish. However, the current population predominantly consists of immigrants, mainly men aged 35 to 44 years from Ukraine. These results emphasize the need for enhanced epidemiological surveillance of patients of Ukrainian origin.

Introduction

The recent COVID‑19 pandemic contributed to a global decline in TB detection. In Poland, TB registration rates also shifted, dropping from 14.3 and 13.9 per 100 000 population in 2018 and 2019, respectively, to 8.8 and 9.7 per 100 000 population, respectively, during the 2020 and 2021 pandemic period.^1-5 These changes were likely influenced by sanitary restrictions, limited access to medical care, and reduced disease detection. Furthermore, mandatory lifestyle changes may have reduced the risk of TB transmission in the community.

In 2022, the TB reporting rate in Poland increased as compared with the pandemic years, reaching 11.4 per 100 000 population.⁶

Similar values were observed in 2023. That year, a total of 4436 TB cases were reported (reporting rate of 11.8 per 100 000), of which 3920 had no history of anti‑TB treatment and 516 were relapses. Pediatric TB cases (n = 51) accounted for 1.1% of all reported cases. In 2023, TB was culture‑confirmed in 3554 patients, representing 80% of registered cases.⁶

Since 2022, Poland has faced epidemiological challenges due to the influx of war refugees from Ukraine. Data on TB incidence rates among foreigners in Poland are imprecise and difficult to interpret. The National Tuberculosis Incidence Register, established in 1957 and maintained by the Institute of Tuberculosis and Lung Diseases, historically provided basic data on TB incidence in the general population but lacked epidemiological and demographic data on immigrants. Since 2004, however, data on TB cases among immigrants have been recorded in detail. Based on these records, between 2011 and 2021, immigrants with TB accounted for 0.4% to 3.6% of all detected TB cases annually.^2-5 In 2023, this percentage rose with 352 immigrants constituting 7.9% of all registered TB cases.⁶

In Poland, as in other Western European countries, the proportion of newly diagnosed patients with culture‑confirmed excretion of multidrug‑resistant (MDR) bacilli remains low and does not exceed 3% of all TB cases.^2,4-7 In 2023, 99 patients were diagnosed with MDR‑TB in Poland (2.8% of all culture‑confirmed cases), 71 of whom were immigrants (2% of culture‑confirmed TB cases).⁶

In contrast, approximately 15‑fold higher rates than those noted in Poland are reported beyond Poland’s eastern border, in the countries of the former Union of Soviet Socialist Republics (USSR). In the Russian Federation, Belarus, Moldova, and Ukraine, over 25% of newly diagnosed patients are affected by MDR‑TB.^2-7

Drug‑resistant (DR) TB is a serious global health challenge, undermining efforts to control TB effectively. The World Health Organization (WHO) estimates that approximately 450 000 cases of DR‑TB were reported in 2021, an increase by 3.1% as compared with the previous year. MDR‑TB and particularly extensively drug‑resistant (XDR) TB require complex and expensive treatment regimens that last longer and are associated with more adverse effects than standard therapies.⁸ New treatment regimens, such as BPaLM (bedaquiline, pretomanid, linezolid, moxifloxacin), shorten treatment duration to 6 months. However, their high cost and limited availability are significant barriers, especially in low‑income countries.⁹

The Mycobacterium tuberculosis complex (MTBC) strain family known as Beijing (Beijing‑TB) is strongly linked to MDR‑TB, and it is estimated to account for approximately 50% of all TB strains in East‑Asian countries.^10-12 Since its identification nearly 30 years ago, Beijing‑TB has spread globally through migration of the population to all continents and is currently found in most countries, particularly in the countries of the former USSR.^12,13 Consequently, it is likely that many migrants with TB arriving in Poland from the former USSR countries are infected with the Beijing genotype.

The study aimed to conduct an epidemiological, microbiological, and molecular analysis of MDR MTBC strains isolated from patients in Poland between 2018 and 2022. The analysis was conducted within the context of social changes in Poland and Europe resulting from the COVID‑19 pandemic and the ongoing military conflict in Ukraine, with particular focus on TB in immigrants from beyond Poland’s eastern border, where higher incidence rates of MDR‑TB are reported.

Patients and methods

Results

During the study, the epidemiological situation of MDR‑TB in Poland evolved in response to shifting social dynamics (Table 2). In 2018 to 2019, before the COVID‑19 pandemic, approximately 70% of culture‑confirmed MDR‑TB cases involved Poles, 24% concerned Ukrainians, and the remaining 6% involved patients of other or unknown nationality.

During the pandemic years 2020 and 2021, the distribution shifted, with Poles comprising approximately 54%, Ukrainians 32%, and individuals of other nationalities 14% of all registered MDR‑TB cases. The year 2022, marked by the outbreak of war in Ukraine and subsequent population migration to Poland, further altered these proportions. In that year, about 36% of patients with MDR‑TB were Poles, 49% were immigrants from Ukraine, and 15% were of other nationalities. Notably, 2022 also saw a rise in the total number of culture‑confirmed cases of MDR‑TB in Poland (78 patients), nearly matching the combined total of cases reported in 2020 and 2021.

Discussion

Our study provides the first epidemiological analysis of MDR‑TB in Poland involving such a large population of Poles and immigrants. The findings highlight an important problem for Poland: the substantial migration of war‑affected populations from Ukraine, a country with a much more difficult epidemiological landscape of TB than Poland.

As demonstrated in previous sections, a considerable proportion of the immigrants are infected with the pre‑XDR and XDR strains of TB as well as the Beijing genotype.

Historically, until 2015, the highest TB incidence rates in Poland were observed among individuals older than 65 years of age. More recently, according to the National Tuberculosis Registry, the largest proportion of patients with TB are now younger, professionally active people aged 45 to 65 years (45.5%).²⁰ Our analysis of the immigrant population with MDR‑TB between 2018 and 2022 shows that a majority of cases involved men aged 35 to 44 years, a generally socially and professionally active and mobile group. This trend was evident both before and during the COVID‑19 pandemic, as well as just before the outbreak of the war.

The armed conflict has changed the reasons for migration to Poland. Since the war began, 75% of Ukrainian citizens who crossed the Ukrainian–Polish border have been adults, with 96% being women with children and 3% men.²¹ It is anticipated that, in the coming years, the number of TB cases in this population will rise due to the transmission of TB and the progression from latent TB infection to active disease. The risk of TB among immigrants is highest within the first 2 to 5 years after migration and remains elevated for over a decade. War migrants are particularly vulnerable, as they often face conditions that increase the risk of TB transmission, such as overcrowded camps, inadequate nutrition, and elevated stress levels. Additionally, after resettling, these individuals may encounter significant barriers to accessing health care services in the host country, which can further hinder timely diagnosis and treatment.²²

Among children, we documented only a single case of TB, involving a Ukrainian child infected with MDR‑TB transmitted by the parent. Data on childhood TB in Ukraine remain sparse and likely underestimated, primarily due to insufficient TB registration in both adult and pediatric populations. According to the WHO, only one‑third of patients with TB are registered in the Ukrainian National TB Program, and of these, only 1.8% are pediatric cases.²³ This Figure likely underrepresents the actual prevalence of MDR‑TB among children, which is estimated to account for 27% of all MDR‑TB cases.^21,24 The challenge of addressing pediatric MDR‑TB in Ukraine is further complicated by the high incidence of HIV infections, which affect approximately 2% of the population of Ukrainian children younger than 15 years.²⁵

Using the definition of pre‑XDR and XDR‑TB, recommended by the WHO until 2021, this analysis of 250 patients identified 109 cases (43.6%) of MDR‑TB, 78 (31.2%) of pre‑XDR‑TB, and 63 (25.2%) of XDR‑TB. Among the Polish patients, pre‑XDR and XDR resistance was more common, whereas MDR resistance combined with sensitivity to additional drugs prevailed among the immigrants. One potential explanation for this discrepancy is the predominance of Beijing 265 strains in the Polish population and Beijing 1 strains among the immigrants. The Beijing strains are known to be associated with drug resistance and are more likely to acquire resistance than other molecular types. However, they are not a genetically and phenotypically homogeneous group, as they can also occur in a drug‑sensitive form.²⁶ Previous studies conducted in Poland have identified both drug‑resistant and drug‑sensitive patients with TB infected with the Beijing 1 spoligotype. Additionally, drug‑resistant cases have been linked to Beijing 265 and Beijing 541 strains.^27,28

In comparison with our previous studies, this analysis highlights a significant increase in the number of patients with MDR‑TB resistant to additional drugs in Poland in recent years.²⁹ Between 2000 and 2009, approximately 14% of MDR strains were resistant to FLQs, and 11% were resistant to SLIDs. Currently, as many as 40% of MDR strains exhibit resistance to FLQ—an essential drug in the treatment of MDR‑TB, particularly when first‑line drugs are not tolerated. The primary cause of MTBC drug resistance to FLQs is the excessive and uncontrolled use of these drugs in the treatment of bacterial infections other than TB. High rates of FLQ‑resistant TB have been reported in the Philippines, India, and the United States.^30-33 However, the extent of MTBC resistance to FLQs has not been sufficiently investigated, with existing data remaining limited and underreported.

Ukraine is one of the countries where more than one‑third of patients with TB in the general population are infected with the pre‑XDR or XDR form of the disease.³⁰ These forms are particularly prevalent in the south‑eastern regions of the country.³⁴

In 2018, the results of the first national study on anti‑TB drug resistance in Ukraine were published, revealing that nearly a quarter of new cases and 60% of previously treated cases were those of MDR‑TB. The highest incidence of MDR‑TB is observed in the south‑eastern regions, where it accounts for more than 30% of newly detected cases in areas such as Dnipropetrovsk, Kherson, Luhansk, and Autonomous Republic of Crimea. In the central regions, 10% to 20% of newly diagnosed patients have MDR‑TB, while in several western regions (Zakarpattia, Ivano‑Frankivsk, and Kyiv) the prevalence is below 10%.³⁵

However, there is a lack of complete epidemiological data and up‑to‑date national reports on TB in Ukraine. The current geopolitical situation further hampers effective surveillance of the epidemiological situation regarding TB in the country.

Our study identified 179 patients (71.6%) infected with Beijing‑TB. This result represents an almost 10‑fold increase, as compared with the prevalence of Beijing‑TB strains detected among patients with MDR‑TB in Poland in 2000.³⁶ It is important to note that between 2000 and 2009, Beijing‑TB was less often reported in Poland among immigrants (40.8%), primarily from Chechnya (38%) and Vietnam (24%), and more commonly among Poles (59.2%).²⁷ Currently, according to our study, there has been nearly a 10% increase in the incidence of Beijing‑TB among immigrants (50.2%). This shift is probably due to the influx of immigrants across the Polish–Ukrainian border, which significantly increased after 2014 as a result of the armed conflict in the eastern part of Ukraine.

We observed that Beijing‑TB was the dominant form in both the immigrant population (90 cases, 76.9% of the immigrant population) and the Polish population (89 cases, 66.9% of the Polish population). This finding is not in line with research conducted by Bakuła et al,³⁷ who reported that MDR Beijing‑TB was present in 66.7% of the Poles and 33.3% of immigrants. This discrepancy is likely due to the nature of Bakuła’s study sample, which was limited to only 2 regions of Poland and included just 39 patients (30 Poles and 9 immigrants), making it less representative of the general population.

Molecular studies on the epidemiology of MTBC strains circulating among patients in Ukraine are limited to selected areas of the country. In the southern and eastern regions, there has been a noticeable increase in the incidence of the Beijing molecular family. In 2007, the Beijing family accounted for 30.5% of TB cases in new patients and 54.8% in previously registered patients in the Odessa and Mykolaiv regions, while in 2018, 81% of cases in Kharkiv were attributed to this strain.^38,39 These regions are located along transport routes connecting Asia with Europe, which may partly explain the high prevalence of the Asian Beijing strain. However, the molecular epidemiology of TB in the central and western Ukraine remains unclear due to the limited research conducted in these regions.

It is also worth noting that our analysis identified Beijing‑TB in patients of other nationalities, including individuals from Moldova, Vietnam, Armenia, Georgia, Indonesia, Russia, Turkey, and Uzbekistan. This finding further supports the global spread of Beijing‑TB.^12,18