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

In order to improve the appropriateness of contact examinations, we investigated the characteristics of secondary tuberculosis cases.

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.

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.

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.