Abstract: Objective To understand the detection of active TB in household close contacts of the smear positive pulmonary tuberculosis patients in Guangzhou city and related influencing factors. Methods Through stratified random sampling method, we selected 6 districts from Guangzhou city, and screened a total of 5664 household close contacts of smear positive pulmonary tuberculosis registered between January 2011 and December 2011, 5206 contacts accepted the screening, 629 contacts younger than 15 years old received tuberculin pure protein derivatives (BCG-PPD) skin test among which 144 of them had tuberculin reaction ≥15 mm or with strong positive reactions such as blisters; 4577 contacts aged ≥15 received chest X-ray, for those with abnormal shadow received sputum smears and sputum cultures examination. SPSS 16.0 statistical analysis software was used for data analysis and P<0.05 is considered statistically significant.  Results  The active pulmonary tuberculosis detection rate among household close contacts was 3.6% (187/5206), the detection rate of smear-positive patients was 0.7% (36/5206), the detection rate of culture-positive patients was 1.3% (66/5206). Among 629 contacts of children below 15 years old, 485 had positive and moderate positive BCG-PPD skin test, 144 had strongly positive reaction. The detection rate of active pulmonary tuberculosis in children with strongly positive BCG-PPD skin test was 5.6% (8/144). Male and female active pulmonary tuberculosis detection rate among household contacts was 3.7% (86/2348) and 3.5% (101/2858) respectively, the difference is not statistically significant (χ²=0.062, P>0.05). In terms of the dif-ferent relationship with the index cases, the detection rate among couples, parents, siblings, children and other relation contacts was 4.4% (74/1675), 4.3% (34/794), 5.7% (29/507), 2.4%（40/1682） and 1.8%（10/548） respectively. The difference is statistically significant by relationship (χ²=23.119, P<0.01). The detection rate of close contacts of new smear positive index cases was 3.9% (160/4131), higher than 2.5% (27/1075) of those contacted with retreatment index cases. The difference is statistically significant (χ²=4.566, P<0.05).   Conclusion The screening of household contacts of smear positive pulmonary tuberculosis index cases is an effective method for active case detection; especially we should give attention to contacts of new patients, and the couples, parents, and siblings of the patients.

Key words: Tuberculosis, pulmonary/prevention &, control, Contact tracing, Guangzhou city