Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Observational Study
. 2019 May 9;9(5):e029295.
doi: 10.1136/bmjopen-2019-029295.

Transmission of tuberculosis and predictors of large clusters within three years in an urban setting in Tokyo, Japan: a population-based molecular epidemiological study

Kiyohiko Izumi  1 , Yoshiro Murase  2 , Kazuhiro Uchimura  1 , Aya Kaebeta  3 , Keiko Ishihara  3 , Sumi Kaguraoka  3 , Takemasa Takii  2 , Akihiro Ohkado  1
Affiliations
Observational Study

Transmission of tuberculosis and predictors of large clusters within three years in an urban setting in Tokyo, Japan: a population-based molecular epidemiological study

Kiyohiko Izumi et al. BMJ Open. .

Abstract

Objective: Molecular epidemiology is a promising tool for understanding tuberculosis transmission dynamics but has not been sufficiently utilised in Asian countries including Japan. The aim of this study was to estimate the proportion of TB cases attributable to recent transmission and to identify risk factors of genotype clustering and the development of large clusters within 3 years in an urban setting in Japan.

Design and setting: Long-term cross-sectional observational study combining the characteristics of patients with culture-positive TB notified in Shinjuku City, Tokyo (2002-2013), with genotype data of Mycobacterium tuberculosis. PRIMARY OUTCOME MEASURE: Genotype clustering rate and association between genotype clustering status and explanatory variables.

Results: Among 1025 cases, 515 were localised within 113 genotype clusters. The overall clustering rate was 39.2%. Significantly higher rates were found in patients aged <40 years (adjusted odds ratio (aOR)=1.73, 95% CI 1.23 to 2.44), native Japanese individuals (aOR=3.90, 95% CI 2.27 to 6.72), full-time workers (aOR=1.63, 95% CI 1.17 to 2.27), part-time/daily workers (aOR=2.20, 95% CI 1.35 to 3.58), individuals receiving public assistance (aOR=1.81, 95% CI 1.15 to 2.84) and homeless people (aOR=1.63, 95% CI 1.02 to 2.62). A significant predictor of large genotype clusters within 3 years was a registration interval ≤2 months between the first two cases in a cluster.

Conclusion: Our results indicated that a large proportion of patients with culture-positive TB were involved in the recent TB transmission chain. Foreign-born persons still have a limited impact on transmission in the Japanese urban setting. Intensified public health interventions, including the active case finding, need to focus on individuals with socioeconomic risk factors that are significantly associated with tuberculosis transmission and clusters with shorter registration intervals between the first two cases.

Keywords: Rflp; clustering rate; foreign-born; homeless.

PubMed Disclaimer

Conflict of interest statement

Competing interests: None declared.

Figures

Figure 1
Figure 1
Number of reported cases of TB, including culture-positive cases, strain-typed cases and genotype clusters, in Shinjuku during 2002–2013. RFLP, restriction fragment length polymorphism; TB, tuberculosis.
Figure 2
Figure 2
Cumulative clustering rate (restriction fragment length polymorphism, Shinjuku 2002–2013).
See this image and copyright information in PMC

References

    1. World Health Organization. Global tuberculosis report 2018. Geneva, 2018.
    1. Lönnroth K, Migliori GB, Abubakar I, et al. . Towards tuberculosis elimination: an action framework for low-incidence countries. Eur Respir J 2015;45:928–52. 10.1183/09031936.00214014 - DOI - PMC - PubMed
    1. de Vries G, Aldridge RW, Cayla JA, et al. . Epidemiology of tuberculosis in big cities of the European Union and European Economic Area countries. Euro Surveill 2014;19:1–8. 10.2807/1560-7917.ES2014.19.9.20726 - DOI - PubMed
    1. Hest NA, Aldridge RW, de Vries G, et al. . Tuberculosis control in big cities and urban risk groups in the European Union: A consensus statement. Euro Surveill 2014;19:1–13. - PubMed
    1. Jereb JA. rogressing towards tuberculosis elimination in low-incidence areas of the United States. Recommendations of the Advisory Council for the Elimination of Tuberculosis. MMWR Recomm reports 2002;51(RR-5):1–14. - PubMed

Publication types