[Outbreaks of tuberculosis in facilities used by an unspecified number of people near a train station - problems regarding tuberculosis in urban areas ].

OBJECTIVES

To report on the mass outbreak of tuberculosis (TB) in an urban area and to discuss current issues regarding the problem of TB in the metropolis.

MATERIALS AND METHODS

Case studies were mainly carried out. Discussions on the route of infection are based on the results of DNA fingerprinting analysis for M. tuberculosis and on information obtained by epidemiological research.

RESULTS

In an approximately 500-meter vicinity around Kawasaki Station in Kawasaki City, nine incidences of people contracting TB were reported during the period of one year and five months starting February 2005. Seven of the nine patients were resistant for streptomycin, and the tubercle bacilli of five patients showed identical patterns based on DNA fingerprinting analysis. These nine patients were relatively young, ranging from 16 years to 55 years in age, and three of the patients were homeless. The area for daily activities for all nine patients is a neighborhood of Kawasaki Station. Based on results from an epidemiologic survey, it is suspected that nine patients had come into contact with each other TB patient in places such as "Net cafes" before they developed TB.

DISCUSSION

Based on the epidemiological and bacteriological results, the route of infection related to this series of TB outbreak is considered to be facilities used by an unspecified number of people such as "Net cafes." Such "Net cafes" are open 24 hours a day and are used by an unspecified number of people, who go to such places to Internet or enjoy comic books. Recently, there are many "Net cafes" in the city, and has become to be used as temporary places to sleep, not only by young people but also by socially vulnerable people, such as the homeless. This study suggests that infection can happen easily once someone begins to discharge TB bacilli in such environments, due to young people, who for the most part are not infected with TB bacilli, and high-risk people, who have higher probability of developing the disease, sharing a closed space for a long period of time. Such social environments may also affect the distribution of TB to lean towards urban areas. The TB control program in the metropolis should be planned and carried out giving consideration to social aspects.