Evaluation of Tuberculosis Transmission

Abstract

PURPOSE: The purpose of the study was an effort to find out the exact trasmission rate after a known TBC case exposure. METHODS: Last year a medical doctor was diagnosed with active Tb (smear and culture positive and a typical clinical feature).After that fact,an extensive investigation was conducted and all hospital admission records were used to identify a number of 834 patients possible exposed during the defined infectious period.The health department notified most patients who were hospitalized at that period or have visited the outpatient department,and recommended a tuberculin skin test (TST).A total of 749 were presented fo the first evaluation ,but only 580 (570 adults and 10 children) (69.5%) have returned for the re-evaluation after 2 months. RESULTS: From the total number of the 580 fully evaluated subjects,564 (97%) had a negative TST (0-4 mm),2 (0.4%)a TST 5-9 mm and 14 (2.4%) a TST >10 mm.Only 1 child ,aged 5 years,had a documented TST conversion (from 0 to 12 mm).This no -Greek origin child had no other exposure to TB than that exposure in the outpatient department (2 visits).All other 13 TST positive patients were also of no- Greek origin,from countries with a high prevalence of TBC or countries with a high vaccination program.Only 1 subject of these 13 has reported a possible exposure to another TBC case.No active TBC case was identified.Despite efforts ,only 36% of the children identified as possible exposured completed the full screening. CONCLUSIONS: Our data suggest that the transmission of TBC depends on different factors and not only to a simple exposure. CLINICAL IMPLICATIONS: This study points the challenge for health authorities to balance the responsibility for a promptly evaluation of patients and or people exposed to TBC cases,for a better recording of TBC exposure prevalence.