Background: In early 2001 there were indications that tuberculosis (TB) was increasingly becoming a
problem among drug addicts and homeless persons in Rotterdam, after a periodical screening was
discontinued in 1997. A contact investigation around a homeless drug addicted man in Rotterdam
with infectious pulmonary TB is described. Contact investigation: A total of 507 drug addicts, homeless
persons, and staff of facilities for these risk groups were examined with tuberculin skin testing (TST) and
chest radiography. DNA fingerprinting of mycobacteriological cultures through Restricted Fragment
Length Polymorphism methodology and molecular epidemiology investigation through cluster analysis
were performed. Outcome: TST showed an infection prevalence of 29%, especially among staff of services
for drug addicts and homeless persons. Six persons with active intrathoracic TB were identified. Cluster
analysis demonstrated no relation with the initial case but showed intense transmission of TB among
drug addicts and homeless persons in Rotterdam by multiple sources. As a consequence of the findings, a
proposal to the Council of the City of Rotterdam resulted in the re-introduction of a comprehensive TB
screening programme among these risk groups with mobile digital X-ray units (MXUs). Conclusion: This
contact investigation gradually obtained the characteristics of a screening of drug addicts and homeless
persons. Novel technologies, such as MXUs, facilitate appropriate and efficient outreach approaches to
TB control among difficult-to-reach groups. This method and knowledge of individual fingerprints and
clusters of TB patients are indispensable for underpinning proposals for change of local TB control
strategies and convincing local authorities of the rationale.
Keywords: DNA fingerprinting, policy implications, risk groups, screening, tuberculosis
From contact investigation to tuberculosis screening of drug addicts and homeless persons in Rotterdam
