Immigrants do not transmit tuberculosis more than indigenous patients in Catalonia (Spain)

Background: Immigrants may not transmit tuberculosis (TB) more than indigenous patients. The objective was to study the prevalence of TB infection among contacts of immigrant and indigenous TB patients and the risk factors associated with latent TB infection. Methods: Contacts of TB cases recorded in 2005 and 2006 were surveyed using a standardized Health Department questionnaire. Infections were diagnosed using the tuberculin skin test (TST) (cutoff > 5 mm). The risk of infection was determined by multivariate logistic regression and the adjusted odds ratios (aOR) with the 95% confidence intervals (CI) were calculated. Results: The study of contacts was completed in 1329 cases of TB. The prevalence of infection was 32.3% (3038/9406) in all contacts, 41.4% in contacts of immigrant cases and 29.2% in contacts of indigenous cases. In the multivariate analysis, immigrant index cases were not associated with an increased risk (aOR = 0.9; 95%CI: 0.8-1.0). The prevalence of TST conversion was 10.0% (296/2969) in all contacts, 11.2% in immigrant contacts and 9.7% in indigenous contacts (p = 0.158). Conclusions: Immigrants do not transmit TB more than indigenous TB patients. Infections which may have occurred in the countries of origin of immigrants were detected by the systematic study of contacts. (C) 2013 Elsevier Ltd. All rights reserved.