ABSTRACT
SETTING: Shinjuku City, Tokyo, Japan. OBJECTIVE: To evaluate the status of transmission of Mycobacterium tuberculosis in Shinjuku City to allocate resources efficiently and effectively for a successful tuberculosis (TB) control programme. DESIGN: Observational descriptive study combining the genotype data of M. tuberculosis with TB patient profiles. RESULTS: The genotype clustering rate was significantly higher in males (adjusted odds ratio [aOR] 1.94, 95%CI 1.04-3.65, P = 0.038), patients aged <40 years (aOR 2.09, 95%CI 1.17-3.71, P = 0.012) and the homeless (aOR 2.72, 95%CI 1.42-5.20, P = 0.002), and was lower for the foreign-born (aOR 0.21, 95%CI 0.06-0.76, P = 0.017). Among 45 genotype clusters containing 152 TB patients, 26 clusters containing 102 patients (67.1%) were composed of a mix of homeless and non-homeless patients. One of the mixed clusters included an 8-month-old infant born in Japan. CONCLUSION: The study revealed that M. tuberculosis transmission occurred more frequently among the homeless than in non-homeless persons. However, transmission by casual contact between the homeless and the general population was also shown to occur.