Prevalence of tuberculosis in household contacts of sputum smears positive cases and associated demographic risk factors.

Pulmonary tuberculosis (PTB) is transmitted by aerosolized droplets nuclei. Home is the vulnerable place for transmission of this disease to its contacts. Risk factors associated with this contact transmission may differ according to locality. This study aims to determine the prevalence of household contact (HC) PTB and examine the risk factors contributing to it. A cross-sectional study was conducted to determine the prevalence of HC TB among HCs aged > 5 years in Dharan. During the study period (June 2009 - May 2010), 184 index cases with sputum smear positive for AFB and their 802 HCs were included. Three sputum specimens were collected from each HCs and examined microscopically for AFB detection. The prevalence of HC TB was found to be 1.6%. The result was statistically associated (P < 0.05) with illiterate HCs (OR= 5.77, 95%CI =1.52-21.81), close proximity with ICs (OR=3.07, 95%CI = 1.02-9.25), primary relatives to ICs (OR= 4.85, 95%CI = 1.07-22.05) and slum dweller (OR = 4.56, 95%CI = 1.25-16.71). Similarly, AFB positivity was associated (P<0.05) with household crowding (OR = 7.46, 95%CI = 2.36-23.49), room size < or = 10 x 10 feet (OR=4.05, 95%CI = 1.23-13.25), firewood user while cooking (OR = 5.96, 95%CI = 1.92-18.45). The prevalence of HCs tuberculosis is found to be 1.6%. Poverty, illiteracy, overcrowding, close proximity, close relation with ICs, firewood while cooking, slum dweller, are major factors highlighted by this study as risk factors of contact TB. Our results recommend a much better contact tracing and treatment program.