Factors associated with tuberculin skin test positivity among household contacts of smear positive pulmonary tuberculosis cases in Umerkot, Sindh

Tuberculosis is on constant rise in nearly all parts of the globe and more so in developing countries. It is recognized a major public health problem in Pakistan with an incidence of 181/100,000 population during 1998. Household contacts of acid-fast bacilli (AFB) smear-positive cases are known to be the high-risk group for tuberculin skin test positivity in other parts of world but in the developing countries including Pakistan there is dearth of such knowledge. The objective of this study was to estimate the prevalence of and identify factors associated with tuberculin skin test positivity among household contacts of AFB smear-positive pulmonary tuberculosis cases in Umerkot, Sindh. This cross-sectional study was conducted among the household contacts of smear positive tuberculosis cases, registered at the clinic of Umerkot anti-tuberculosis association,s a Non-Governmental organization (NGO) at Umerkot, from August 1999 to September 1999. The contact\u27s Mycobacterium tuberculosis infection status was assessed by using tuberculin skin test. On the day of tuberculin skin test\u27 a predesigned questionnaire was administered to collect the data on factors hypothesized for their association with the tuberculin skin test positivity among contacts. Multiple logistic regressions were used to determine factors associated with tuberculin skin test positivity. The prevalence of tuberculin skin test positivity was found to be 49\u2747o among household contacts of smear-positive tuberculosis cases\u27 And the prevalence of Mycobacterium tuberculosis affected households (household having at least one tuberculin skin test positive contact) was found tobe\u27707o\u27 The multivariate analysis for all household contacts showed that after adjusting for other variables; age of household contact, gender of index case, educational status of index case, intensity of smear positivity of index case (aOR 2.8, 95% CI, 1.1 – 4.1) and sleeping sites of contact relative to index case; for same bedroom (aOR 3\u273,957o CI, 1\u276 - 6\u275) or for same bed (aOR 2.5, 95% CI, 1.4 - 4.5) were the important determinants of tuberculin skin test positivity among household contacts of smear-positive tuberculosis (index) cases. The multivariate analysis at household level showed that after adjusting for other variables; duration of TB of index case (aOR 1.1, 95% CI, 1.02 - 1.13) and intensity of smear-positivity of index case (aOR 4.8, 95% CI, 1.9 - 25.1) were the important predictors for Mycobacterium tuberculosis affected households. Household contacts should be further evaluated for TB and treated accordingly. Furthermore, index cases treated as early as possible, thus the epidemiological chain of transmission is broken. There is a need to decrease the tuberculin skin test positivity among household contacts through health education