[Importance of a symptomatic visit in tuberculosis contacts--classification of secondary cases].

OBJECTIVES: In order to improve the appropriateness of contact examinations, we investigated the characteristics of secondary tuberculosis cases. SUBJECTS AND METHODS: We included tuberculosis patients that were located in Kawasaki City between 2008 and 2011. The patients were considered as 2 separate groups: those with tuberculosis following contact with index cases registered in Kawasaki City and those with tuberculosis who were located in Kawasaki City. Secondary cases were defined as subjects who underwent a contact examination and developed active tuberculosis within 2 years from the last contact with the index case. The secondary cases were classified by diagnostic method, time, and sputum smear test results, followed by consideration of improvement measures. RESULTS: There were 1196 tuberculosis patients and 6157 subjects who underwent a contact examination. Of these, 35 patients developed tuberculosis secondary to index cases registered in Kawasaki City. These 35 cases were classified by diagnostic methods. Diagnosis occurred during a contact examination in 31 cases and during a symptomatic visit in 4 cases. There were 2 sputum smear-positive patients detected in a contact examination that was conducted > or = 6 months after contact. These 2 cases had a symptomatic cough, but did not visit a medical institution. There were 39 patients with secondary tuberculosis who were located in Kawasaki City. These 39 cases were also classified by diagnostic methods. Diagnosis occurred during a contact examination in 33 cases and during a symptomatic visit in 6 cases. There were 4 sputum smear-positive patients detected in a contact examination that was conducted > or = 6 months after contact. These 4 cases had a symptomatic cough, but did not visit a medical institution. DISCUSSION: Of the secondary cases, a sputum smear-positive state was detected in some of the patients at the time of a contact examination that was conducted > or = 6 months after contact. However, secondary cases should be discovered at a sputum smear-negative stage. Appropriate education regarding the importance of a medical visit at the onset of symptoms could decrease the number of patients that are identified in the sputum smear-positive state during a contact examination that occurs at least 6 months after contact.