title: Transmission of Mycoba cterium tuberculosis to households of tuberculosis patients: a comprehensive contact tracing study.
abstract: BACKGROUND
  Tuberculosis (TB) continues to be a major health problem in developing countries. Contact investigation is the most appropriate strategy to interrupt transmission and subsequent development of TB.
  
  
  METHODS
  This cross-sectional study was conducted to assess the impact of contact screening on case-finding by using tuberculin skin test chest radiography. Contacts of smear-positive patients with pulmonary TB (index cases) were diagnosed and registered in our center during 2002 - 2004. Contacts, defined as household members living with index cases for >30 days, were screened by sputum examination, tuberculin skin test, and chest radiography.
  
  
  RESULTS
  Sixty-eight patients with smear-positive pulmonary TB were considered as index cases. A total of 224 close contacts with index cases (an average of 3 contacts for each index case) were detected. Age among contacts ranged from 6 months to 74 years. Eighty-three percent of contacts were Iranians and 17% were Afghans. Abnormal radiographs were seen in 49.6% of contacts. Sixteen point five percent of contacts had a positive tuberculin skin test of >10 mm; 7.6% had a positive sputum smear. The mean +/- SD age of Iranian contacts (29.1 +/- 16.6 years) was significantly (P < 0.001) higher than that of Afghans (18.6 +/- 14.1 years). Cavitary formation, nodular pattern, and infiltration were found to have a strong association with a positive sputum smear for acid fast bacilli (100%, 100%, and 87%, respectively).
  
  
  CONCLUSIONS
  The rate of TB in contacts was higher than other similar studies. Earlier detection and treatment of adults with TB could interrupt transmission and be a step towards eliminating childhood TB. Contact control and source-case investigations should be emphasized for TB control. Novel strategies are needed to maximize the number of contacts who are not only identified and evaluated, but also completely treated.
authors.affiliation: National Research Institute of Tuberculosis and Lung Disease, Masih Daneshvari Hospital, Tehran, Iran. skh@nritld.ac.ir
authors.forename: Soheila
authors.initials: S
authors.lastname: Khalilzadeh
authors.forename: Heidar
authors.initials: H
authors.lastname: Masjedi
authors.forename: Mostafa
authors.initials: M
authors.lastname: Hosseini
authors.forename: Arash
authors.initials: A
authors.lastname: Safavi
authors.forename: Mohammad-Reza
authors.initials: MR
authors.lastname: Masjedi
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002648:Child; D002675:Child, Preschool; D016358:Contact Tracing / Q000379:methods*; D003430:Cross-Sectional Studies; D018562:Disease Transmission, Infectious / Q000706:statistics & numerical data*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007223:Infant; D007492:Iran / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009169:Mycobacterium tuberculosis / Q000302:isolation & purification*; D013902:Radiography, Thoracic; D012189:Retrospective Studies; D013183:Sputum / Q000382:microbiology; D014374:Tuberculin Test; D014376:Tuberculosis / Q000175:diagnosis* / Q000453:epidemiology / Q000635:transmission*