Long-term course of Mycobacterium tuberculosis infection in Swedish birth cohorts during the twentieth century

• Published in: The international journal of tuberculosis and lung disease Vol. 15; no. 6; pp. 736 - 740
• Main Authors: Winqvist, N, Björk, J, Miörner, H, Björkman, P
• Format: Journal Article
• Language: English
• Published: Paris, France IUATLD 01-06-2011; International Union against Tuberculosis and Lung Disease
• Subjects: Age-Cohort Modelling; Bacterial diseases; Biological and medical sciences; Clinical Medicine; Cohort Effect; Cohort Studies; Databases, Factual; Epidemic; History, 20th Century; Human bacterial diseases; Humans; Incidence; Infectious diseases; Klinisk medicin; Latent Tuberculosis; Lungmedicin och allergi; Medical and Health Sciences; Medical sciences; Medicin och hälsovetenskap; Pneumology; Respiratory Medicine and Allergy; Respiratory system : syndromes and miscellaneous diseases; Risk Factors; Sex Distribution; Sweden; Sweden - epidemiology; Tuberculosis; Tuberculosis - epidemiology; Tuberculosis - history; Tuberculosis and atypical mycobacterial infections; Sweden; Europe; Epidemic; Respiratory disease; tuberculosis; Latent tuberculosis; Mycobacterial infection; Long term; Infection; Sweden; Mycobacterium tuberculosis; Mycobacteriales; Bacteriosis; Mycobacteriaceae; Bacteria; Actinomycetes; Pneumology; age-cohort modelling
• ISSN: 1027-3719; 1815-7920; 1815-7920
• DOI: 10.5588/ijtld.10.0683

SETTING: Sweden under transition from high to low tuberculosis (TB) incidence from 1920 to 2009.OBJECTIVE: To correlate estimates of TB infection in birth cohorts with the longitudinal incidence of active TB to assess the long-term risk and time pattern of reactivated TB.DESIGN:
Time trend analysis on TB incidence using age-cohort modelling.RESULTS: The overall TB incidence decreased from 700 per 100 000 population in 1920 to 1.4 in 2009 in the Sweden-born population. The estimated disease rate (number of cases divided by the estimated number of infected
in 1967), for each birth cohort between 1920 and 1940, was stable on a level between 9.8% and 10.7%. The reactivation rate of latent TB infection (LTBI) was 2% after 1967, when indigenous transmission had disappeared.CONCLUSION: Although approximately 10% of persons with LTBI developed
active TB, the majority of cases occurred shortly after infection, and the rates of reactivation declined over time. This indicates extensive spontaneous clearance of LTBI.