Screening for pulmonary tuberculosis among immigrants: estimated effect on severity of disease and duration of infectiousness.

OBJECTIVE: To estimate the effect of tuberculosis screening among recent immigrants on the severity of disease at diagnosis and on the duration of the infectious period. DESIGN: Comparison of pulmonary tuberculosis cases among immigrants detected through screening with those detected passively, using information from the Netherlands Tuberculosis Register. PARTICIPANTS: Immigrants from highly endemic countries diagnosed with culture-positive pulmonary tuberculosis within 30 months after arrival in The Netherlands, 1993 through 1998. OUTCOME MEASURES: Severity of disease (smear-positive disease, hospitalisation, case fatality) and duration of symptomatic period. RESULTS: A total of 882 bacteriologically confirmed tuberculosis patients from highly endemic countries had been in The Netherlands less than 30 months, and were detected through screening (454), or passively (368). Compared with patients detected passively, patients found through screening were less often sputum smear-positive (OR 0.5, 95%CI 0.3-0.8) and less often hospitalised (OR 0.2, 95%CI 0.1-0.2). Those detected through screening had a shorter symptomatic period. Screening is estimated to have reduced the infectious period by approximately 33%. CONCLUSION: The screening programme detected cases earlier, resulting in fewer hospital admissions, shorter duration of symptoms and therefore probably reduced tuberculosis transmission.