Abstract: Objective To investigate the status of TB case detection through investigation of close contacts of smear positive tuberculosis patients, provide scientific basis for the development of TB prevention and control strategy. Methods The household close contacts of 1 138 smear positive TB cases were investigated by X-ray and sputum smear test. The yield of TB cases in patient’s spouses, parents and children and in contacts with or without suspicious TB symptoms were analyzed respectively. The yield in contacts of patients with different level of smear Results was also compared. Results The yield of active PTB was 3.3% in household close contacts of smear positive PTB cases. The detection rate of active PTB was highest in spouses which was 1.9 times and 16 times higher than in the parents and the children of patients, respectively. The detection rate was 6.4 times higher in close contacts with suspicious TB symptoms than without symptoms. And the detection rate between these two groups are significant different（μ＝7.8，P＜0.01). Conclusions The prevalence of active PTB is significantly higher in household contacts than in general population, especially for the spouses of the patients. We should give special attention to contacts with suspicious TB symptoms and household contacts of patients with higher level of bacterial discharge. Therefore, we should strengthen the monitoring and examination of close contacts of smear positive PTB patients in order to detect the patients as early as possible and shorten the TB spreading period to the healthy population.

Key words: tuberculosis,pulmonary/prevention and control, contact tracing