Occurrence of extrapulmonary tuberculosis is associated with geographical origin: spatial characteristics of the Frankfurt TB cohort 2013–2018

Introduction Tuberculosis (TB) is caused by M. tuberculosis complex (MTB) and pulmonary tuberculosis (PTB) is its classical manifestation. However, in some regions of the world, extrapulmonary TB (EPTB) seems to be more frequent. Methods We performed a retrospective cohort study of all TB patients treated at University Hospital Frankfurt, Germany, for the time period 2013–2018. Patient charts were reviewed and demographic, clinical, and microbiological data recorded. Patients were subdivided according to their geographic origins. Results Of the 378 included patients, 309 were born outside Germany (81.7%). Three WHO regions were significantly associated with the occurrence of isolated EPTB: the South-East Asian Region (OR 3.37, CI 1.74–6.66, p < 0.001), the African Region (2.20, CI 1.25–3.90, p = 0.006), and the Eastern Mediterranean Region (OR 3.18, CI 1.78–5.76, p < 0.001). On a country level, seven countries of origin could be demonstrated to be significantly associated with the occurrence of isolated EPTB: India (OR 5.58, CI 2.30–14.20, p < 0.001), Nepal (OR 12.75, CI 1.73–259.28, p = 0.027), Afghanistan (OR 3.64, CI 1.14–11.98, p = 0.029), Pakistan (OR 3.64, CI 1.14–11.98, p = 0.029), Eritrea (OR 3.32, CI 1.52–7.47, p = 0.003), Somalia (OR 7.08, CI 2.77–19.43, p < 0.001), and Turkey (OR 9.56, CI 2.52–47.19, p = 0.002). Conclusion Geographical origin is a predictor for the occurrence of extrapulmonary TB. This might be linked to a delay in diagnosis in these patients, as well as specific responsible impairments of the host’s immune system, possible virulence factors of MTB, and relevant comorbidities.