Background: Detection of latent tuberculosis infection is a cost-effective procedure in patients at high risk of developing tuberculosis later and who could benefit from preventive treatment.
Objective: To investigate the risk of latent TB infection (LTBI) among household contacts of newly diagnosed patients with pulmonary tuberculosis in our locality.
Population and methods: 256 household contact to 73 consecutive patients with pulmonary tuberculosis underwent tuberculin skin testing. Transverse induration of greater than 10 mm was defined as positive tuberculin test suggestive of tubercular infection in non BCG-vaccinated contacts and > 15 mm in BCG-vaccinated contacts. All contacts underwent chest radiography and analysis of sputum for detection of acid fast bacilli.
Results: A total of 319 household contacts were registered in the study, of whom 256 (80%) were aged between 1 to 79 years with a mean of (24.94 ±17.47) years. There were more females (n=144) than males (n=112) among the contacts. Tuberculin test was positive in 91 out of 256 contacts (35.5%), of which 67 (73.6%) were contacts of sputum positive patients, while 24 (26.4%) were contacts of sputum negative patients; the difference was statistically significant (p = 0.000). Nine of these contacts were diagnosed as having tuberculosis. The important risk factors for transmission of infection were extremities of age, large family size, contact with an index case who was sputum positive.
Conclusion: The study concluded that high prevalence of infection among close household contacts with cases of tuberculosis. This may be in part due to some health problems and socio-economic status. This high prevalence justifies the prescription of chemopropylaxis for close contacts to decrease the spread of the disease.