Abstract
PURPOSE: Few individuals that are latently infected with M. tuberculosis latent tuberculosis infection(LTBI) progress to active disease. We investigated risk factors for LTBI and active pulmonary tuberculosis (PTB) in Germany. METHODS: Healthy household contacts (HHCs), health care workers (HCWs) exposed to M. tuberculosis and PTB patients were recruited at 18 German centres. Interferon-γ release assay (IGRA) testing was performed. LTBI risk factors were evaluated by comparing IGRA-positive with IGRA-negative contacts. Risk factors for tuberculosis were evaluated by comparing PTB patients with HHCs. RESULTS: From 2008-2014, 603 HHCs, 295 HCWs and 856 PTBs were recruited. LTBI was found in 34.5% of HHCs and in 38.9% of HCWs. In HCWs, care for coughing patients (p = 0.02) and longstanding nursing occupation (p = 0.04) were associated with LTBI. In HHCs, predictors for LTBI were a diseased partner (odds ratio 4.39), sexual contact to a diseased partner and substance dependency (all p < 0.001). PTB was associated with male sex, low body weight (p < 0.0001), alcoholism (15.0 vs 5.9%; p < 0.0001), glucocorticoid therapy (7.2 vs 2.0%; p = 0.004) and diabetes (7.8 vs. 4.0%; p = 0.04). No contact developed active tuberculosis within 2 years follow-up. CONCLUSIONS: Positive IGRA responses are frequent among exposed HHCs and HCWs in Germany and are poor predictors for the development of active tuberculosis.