Screening for tuberculosis in an urban shelter for homeless in Switzerland: a prospective study

Whereas high risk groups such as asylum seekers are systematically screened for active tuberculosis (TB) upon entry in Switzerland, this strategy does not apply to homeless persons despite a reported high risk. Geneva health and social authorities implemented an intersectoral project to screen for active TB in homeless persons. We aimed to assess acceptability of this program and prevalence of active TB in this group.

This prospective study targeted all homeless adults registering for shelter accommodation in Geneva during winter 2015. Applicants were proposed a questionnaire-based screening ( www.tb-screen.ch ) exploring epidemiological and clinical risk factors for active TB. Participants with a positive score underwent diagnostic procedures at Geneva University Hospital. Enhanced TB surveillance targeting homeless persons in the community was continued 3 months after the study termination.

Overall, 726/832 (87.3%) homeless persons accepted the screening procedure. Most were young male migrants without access to care in Switzerland. Male gender (adjusted OR: 2.14; 95% confidence interval: 1.27-3.62), age below 25 years (aOR: 4.16; 95% CI: 1.27-13.64) and short duration of homelessness (aOR: 1.75; 95% CI: 1.06-2.87) were predictors of acceptance. Thirty (4.1%) had positive screening scores but none of the 24 who underwent further testing had active TB. Post-study surveillance did not identify any incident case in Geneva.

Active TB screening targeting highly mobile homeless persons in shelters was well accepted and feasible. The participants' sociodemographic profile highlighted the heterogeneity of homeless groups in Europe and the null TB prevalence the variability of their active TB risks. These findings underline the feasibility of health programs targeting this hard to reach group and the need for close monitoring of this social group considering the rapid changes in international mobility patterns to tailor preventive and screening strategies to the local context.