Transmission of Mycoba cterium tuberculosis to households of tuberculosis patients: a comprehensive contact tracing study.

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). CONCLUSION 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.

[1]  B. Marais Tuberculosis in children , 2008, Pediatric pulmonology.

[2]  Bower Rj Tuberculin skin testing in BCG-vaccinated populations of adults and children at high risk for tuberculosis in Taiwan. , 2004 .

[3]  C. Sant’Anna,et al.  [Tuberculosis contact tracing among children and adolescents, Brazil]. , 2004, Revista de saude publica.

[4]  R. J. Bowerman Tuberculin skin testing in BCG-vaccinated populations of adults and children at high risk for tuberculosis in Taiwan. , 2004, The international journal of tuberculosis and lung disease : the official journal of the International Union against Tuberculosis and Lung Disease.

[5]  R. Webb,et al.  Tuberculosis contact investigation in a rural state. , 2003, The international journal of tuberculosis and lung disease : the official journal of the International Union against Tuberculosis and Lung Disease.

[6]  M. Reichler,et al.  Outcomes of contact investigation among homeless persons with infectious tuberculosis. , 2003, The international journal of tuberculosis and lung disease : the official journal of the International Union against Tuberculosis and Lung Disease.

[7]  K. McAdam,et al.  Risk factors for tuberculosis infection in sub-Saharan Africa: a contact study in The Gambia. , 2003, American journal of respiratory and critical care medicine.

[8]  K. McAdam,et al.  Risk factors for tuberculosis infection in children in contact with infectious tuberculosis cases in the Gambia, West Africa. , 2003, Pediatrics.

[9]  E. Migliore,et al.  Tuberculin reactivity in adult BCG-vaccinated subjects: a cross-sectional study. , 2003, The international journal of tuberculosis and lung disease : the official journal of the International Union against Tuberculosis and Lung Disease.

[10]  J. Mohle-Boetani,et al.  Yield of source-case and contact investigations in identifying previously undiagnosed childhood tuberculosis. , 2003, The international journal of tuberculosis and lung disease : the official journal of the International Union against Tuberculosis and Lung Disease.

[11]  S. Akhtar,et al.  Prevalence and risk factors associated with tuberculin skin test positivity among household contacts of smear-positive pulnionary tuberculosis cases in Umerkot, Pakistan. , 2002, The international journal of tuberculosis and lung disease : the official journal of the International Union against Tuberculosis and Lung Disease.

[12]  J. Zellweger Tuberculosis in households of index patients: is there another way to control tuberculosis? , 2002, The international journal of tuberculosis and lung disease : the official journal of the International Union against Tuberculosis and Lung Disease.

[13]  A. Harries,et al.  High frequency of tuberculosis in households of index TB patients. , 2002, The international journal of tuberculosis and lung disease : the official journal of the International Union against Tuberculosis and Lung Disease.

[14]  D. Menzies,et al.  Chest radiograph abnormalities associated with tuberculosis: reproducibility and yield of active cases. , 2002, The international journal of tuberculosis and lung disease : the official journal of the International Union against Tuberculosis and Lung Disease.

[15]  M. Chan-yeung,et al.  Contact examination for tuberculosis in Hong Kong is useful. , 2002, The International Journal of Tuberculosis and Lung Disease.

[16]  L. Cuevas,et al.  Use of purified protein derivative to assess the risk of infection in children in close contact with adults with tuberculosis in a population with high Calmette-Guérin bacillus coverage. , 2001, The Pediatric infectious disease journal.

[17]  L. Saiman,et al.  Risk factors for latent tuberculosis infection among children in New York City. , 2001, Pediatrics.

[18]  N. Qualls,et al.  Outcomes of contact investigations of infectious tuberculosis patients. , 2000, American journal of respiratory and critical care medicine.

[19]  E. Vynnycky,et al.  Tuberculin sensitivity: conversions and reversions in a rural African population. , 1999, The international journal of tuberculosis and lung disease : the official journal of the International Union against Tuberculosis and Lung Disease.

[20]  F. Á. Álvarez Gutiérrez,et al.  Investigation of Tuberculosis Contacts in a Nonhospital Pneumology Practice , 1999, European journal of clinical microbiology & infectious diseases : official publication of the European Society of Clinical Microbiology.

[21]  S. Lockman,et al.  Tuberculin reactivity in a pediatric population with high BCG vaccination coverage. , 1999, The international journal of tuberculosis and lung disease : the official journal of the International Union against Tuberculosis and Lung Disease.

[22]  Ayerbe Mateo-Sagasta Mc,et al.  Evaluation of the tuberculosis infection screening program in pediatric population , 1996 .

[23]  M. C. Ayerbe Mateo-Sagasta,et al.  [Evaluation of the tuberculosis infection screening program in pediatric population]. , 1996, Anales espanoles de pediatria.

[24]  D. Snider,et al.  Treatment of tuberculosis and tuberculosis infection in adults and children. American Thoracic Society and The Centers for Disease Control and Prevention. , 1994, American journal of respiratory and critical care medicine.

[25]  C. Murray,et al.  Tuberculosis in developing countries: burden, intervention and cost. , 1990, Bulletin of the International Union against Tuberculosis and Lung Disease.

[26]  M. Iseman,et al.  Guidelines for the investigation and management of tuberculosis contacts. , 1976, The American review of respiratory disease.

[27]  S. Grzybowski,et al.  Contacts of cases of active pulmonary tuberculosis. , 1975, Bulletin of the International Union against Tuberculosis.

[28]  A. Geser,et al.  The distribution of tuberculous infection among households in African communities. , 1960, Bulletin of the World Health Organization.