Wars deeply affect the social order, leading to long-term deterioration in social, cultural, and economic fields. Civil wars, in particular, increase social division, giving rise to acute and chronic crises at both individual and societal levels. The Syrian civil war, which started in 2011, caused the displacement of millions of people; this mass migration spread first within the country and then to neighboring countries. Turkey has been one of the countries most affected by this migration movement. As of June 2023, there are 3,351,582 Syrians registered under temporary protection in Turkey. 98% of this population lives in urban centers, while only 1.83% lives in temporary accommodation centers. With an average age of 22.5 years, this young population has special vulnerabilities in terms of access to health services and infectious disease control. This large-scale population movement has affected the demographic and socioeconomic structure of Turkey and has brought integration problems in many areas, especially in health services (1, 2).

Tuberculosis (TB) is a serious health problem in socioeconomically disadvantaged groups, especially among Syrian refugees, low-income individuals, and those living in slum areas (3). The incidence of TB is not only due to biomedical factors; it is also strongly dependent on social determinants such as poverty, poor living conditions, malnutrition, and limited access to healthcare. Effective TB control is possible not only with medical interventions, but also with multi-sectoral, holistic approaches to these social determinants (4). In regions such as southeastern Turkey, where forced migration and rapid urbanization are intense, the impact of these social inequalities on TB becomes even more pronounced.

There was a downward trend in the incidence of TB in Syria before the war (5). However, the collapse of the national health system and the interruption of vaccination and treatment services with the war brought TB control to a standstill. After the mass migration to Turkey, the share of Syrian refugees in TB cases has increased rapidly. According to the Ministry of Health TB reports, the proportion of foreign nationals among reported TB cases rose from 1.3% in 2011 to 6.8% in 2015 (6). This increase shows that the proportion of the Syrian refugee population in the TB burden has increased significantly over the years.

After the World Health Organization (WHO) declared COVID-19 a global pandemic on March 11, 2020, health systems have come under great pressure. The pandemic has led to disruptions in access to health services; it has caused delays in the diagnosis, treatment and follow-up processes of TB (7, 8). These cuts have disproportionately adversely affected vulnerable groups, especially the Syrian refugee population.

Its location close to the Turkish-Syrian border, its demographic structure directly affected by migration movements, and the increasing Syrian refugee population density over time make the assessment of the TB burden in Mardin province a critical public health priority. Although the regional burden of TB has been discussed in the existing literature, the Syrian refugee patient population has not been examined as a separate analysis. In Turkey, several studies have investigated the epidemiology of tuberculosis in the southern regions, highlighting the influence of migration and refugee populations on TB control efforts (9–11).

In this context, it is aimed to contribute to the strengthening of national and global TB control strategies by retrospectively comparing tuberculosis cases between Syrian refugees and local citizens in Mardin province between 2016 and 2023.

This study was conducted in the Turkish province of Mardin, which borders Syria and is home to a significant Syrian refugee population, and revealed five key differences between local and Syrian refugee patients with tuberculosis (TB). First, BCG scar positivity is significantly lower in Syrian refugees than in local citizens. Second, the use of microbiological diagnostic methods falls short of the World Health Organization (WHO) targets in both groups. Third, treatment success (sum of recovery and treatment completion) is significantly lower in Syrian refugees than in local citizens. Fourthly, the cases referred to another province (“transferred-out”) during treatment were significantly higher in Syrian refugees, and the rate of cases arriving in Mardin province during treatment (“transferred-in”) was noticeably higher in the Syrian refugee population. Fifth, a dramatic decrease in the incidence of TB among Syrian refugees has been observed during the COVID-19 pandemic.

In Turkey, BCG vaccination programs are carried out in line with the World Health Organization’s (WHO) End TB strategy. According to WHO reports and literature studies, BCG vaccination rates in Turkey are around 95% (16–18). On the other hand, according to Syria’s data from the pre-civil war period, BCG vaccination was reported at a rate of 100% (19). However, in our study, a significantly lower BCG scar positivity was found in Syrian adult Syrian refugees compared to the local population. As a matter of fact, even the BCG vaccination rate of 81% reported by Syria to WHO for 2018 is well above the rates found in our study (17). A study of European countries examining the vaccination records of Syrian refugees reported that vaccination rates among Syrian refugees from the Middle East and Africa were significantly lower (20). While the BCG scar positivity rates detected in the local population were consistent with the national data declared by Turkey, the fact that this rate was significantly lower in Syrian refugees indicates the inadequacy of the tuberculosis control system in Syria since before the civil war.

In our study, microbiological diagnosis rates were slightly below the 68% target recommended by the World Health Organization in both patient groups (18, 21). This situation creates significant limitations in terms of identifying drug resistance patterns and conducting effective epidemiological follow-up. BCG scar negativity was significantly more common in the Syrian refugee population, and in this context, it is understandable that microbiological tests were studied at a higher rate in sputum samples due to the predominance of pulmonary involvement, although it is generally considered as underdiagnosis. On the other hand, the high level of BCG scar positivity in the local citizens population reduced pulmonary TB rates due to the immune-mediated protection effect; instead, it may have led to a higher rate of extrapulmonary involvement. This may explain the relatively low rates of microbiological diagnosis in domestic patients.

However, it is clear that bacteriological examinations should be expanded for both groups, especially in tissue tuberculosis. When the national data are examined, it is seen that microbiological confirmation is reported at low rates in tissue-derived TB diagnoses, similar to our study. Although the Turkish National Tuberculosis Control Program emphasizes the need to increase bacteriological diagnosis, in practice the main reason for these low rates is the priority given to pathological examinations in the diagnosis of tissue samples (9, 21). International literature points to similar problems. In a large-scale study based in China, microbiological examination was reported as 49.3% in lung TB cases and only 12.8% in tissue TB cases (22). In the other study, which was conducted in India and included only extrapulmonary tuberculosis (EPTB) cases, bacteriological positivity rate of 34% was obtained by microbiological diagnostic methods in a total of 104 cases. The main reasons for the low microbiological diagnosis are the quality of biopsies or liquid samples taken with low bacillus load in the samples and the quality of the laboratory (23). In global reports, Japan and South Korea were among the countries with low TB burden that met and even exceeded the bacteriological examination target set by WHO (24, 25). For this reason, we believe that clinical awareness trainings should be disseminated to ensure that qualified samples are sent to the laboratory for microbiological examination in all cases where tissue samples are taken.

In our study, a significant difference was found between the local population and the Syrian refugee population in Mardin province in terms of tuberculosis treatment outcomes. Although Directly Observed Treatment (DOT) was carried out at similar rates in both groups and in a way that covered the entire patient population, treatment success was found to be significantly lower in Syrian refugees. In the international literature, there are several studies and WHO reports showing that TB treatment success is lower in Syrian refugees than in the local population (4, 18, 26). It is suggested that this difference cannot be explained only by the application of DOT, but may be related to socioeconomic and structural factors such as the lack of a settled residence of Syrian refugee individuals and their frequent relocation (5, 26–29). The review report published by Pareek et al., which identified the lack of a settled life of Syrian refugees in high-income European countries and reinfection with TB during travels to their homeland as a risk factor, was found to be related to the temporary return of the Syrian refugee population in our study to Syria, especially during religious holidays (27). In addition to the risk factor covering border crossing, in our study, the rate of “transferred-in” and “transferred-out” of Syrian refugees within the country was found to be noticeably higher than the local citizens. In the literature and reports, it has been stated that this relocation may lead to interruption or interruption of the treatment process, and at the same time, it negatively affects contact control, which has a very important place in the control of latent TB infection (20, 27–29). Similarly, in our study, low treatment success in Syrian refugees may be related to social determinants such as relocation and non-sedentary lifestyle, despite the adequacy of DOT administration.

In recent years, as in many countries, decreases in the incidence of TB have been reported in Turkey as well as in the fight against TB. However, there is no reported decrease in the incidence of TB in the Syrian refugee population in the world, and an increase in the incidence of TB in Syrian refugees is reported in the data of Turkey. This indicates that TB has increasingly affected Syrian refugees as a consequence of migration-related vulnerabilities (20, 27–29). In our results, although the TB incidence data were examined on the basis of local and limited number of patients, it remained at lower rates in the Syrian refugee population than in the domestic population in order to give an idea. This situation suggests the possibility of Syrian refugees encountering under-diagnosis in Mardin. The socio-cultural and demographic structure of Mardin province is suitable for the accommodation of Syrian refugees in the local population and even for their cohabitation due to kinship relations (30, 31). It is a well-known fact that TB cases may hesitate to resort to diagnosis and treatment in order not to be exposed to the stigma they may encounter in the social and even health environment (32, 33). The relatively low incidence rates of Syrian refugees observed in Mardin province remained low according to both Turkey data and the incidence data of Syrian refugee TB cases in the world (6, 25, 28, 29). This can be explained by the behavior of not seeking medical help in tuberculosis to avoid social stigma and even for fear of deportation. In the literature, it has been stated that Syrian refugees may exhibit similar behaviors due to fear of social stigma and deportation in the countries they live in (20, 34).

The most prominent data of our study in incidence rates was the abnormal decrease in the incidence of TB in the Syrian refugee population in 2020 and 2021, the years of the COVID-19 pandemic. In the subsequent TB incidences in 2022, an increase was observed in the Syrian refugee population compared to the local population. These findings show that the Syrian refugee population was deprived of health services during the pandemic years, especially in terms of TB diagnosis. Studies have shown that pandemic-specific changes in health systems around the world during the COVID-19 pandemic have resulted in a weakening of TB diagnosis and follow-up chains in Syrian refugee populations, resulting in fewer diagnoses of Syrian refugees and an increased TB burden in the Syrian refugee population (7, 8, 35). As a matter of fact, when the post-pandemic data were examined in our study, the increase in the incidence of TB in Syrian refugees was remarkable. However, despite this, due to the reasons discussed above; societal stigma and fear, and even deprivation of immigration rights, etc.; in the province of Mardin, we think that the Syrian refugee population is still experiencing under-diagnosis. For this reason, TB control programs need to be handled in a confidentiality-assured, anti-stigma, culturally sensitive and accessible structure for Syrian refugees. Studies carried out on a national basis will contribute to revealing this problem more clearly in the future.

This study demonstrates significant differences between local citizens and Syrian refugees with TB in Mardin – a border province with substantial cross-border mobility. Lower BCG scar rates, reduced treatment success, and higher transfer-out rates among refugees highlight challenges in treatment continuity and follow-up. Both groups showed microbiological diagnosis rates below WHO targets, emphasizing the need to expand bacteriological confirmation, particularly for extrapulmonary TB.

Although social cohesion between refugees and locals may appear advantageous, fear of stigmatization may discourage refugees from seeking diagnosis and treatment.

Therefore, TB control in border regions should incorporate refugee-sensitive strategies, including:

Such approaches may strengthen treatment adherence and prevent transmission in mobile and vulnerable populations.