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Canadian Respiratory Journal
Volume 9, Issue 5, Pages 319-323
Original Article

Incidence of Pulmonary Disease Caused by Mycobacteria other than Tuberculosis in British Columbia

R Kevin Elwood,1 Anabelle M Opazo Saez,2 Vittorio Lentini,3 and Ramak Shadmani1

1British Columbia Centre for Disease Control Society, Division of Tuberculosis Control, Vancouver, British Columbia, Canada
2Indiana University School of Medicine, Department of Cellular and Integrative Physiology, Indianapolis, Indiana, USA
3National Defense, Force Health Protection, Communicable Disease Control, Ottawa, Ontario, Canada

Copyright © 2002 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


CONTEXT: The incidence of pulmonary disease due to mycobacteria other than tuberculosis (TB) in Canada has not been documented.

OBJECTIVE: To determine the incidence of pulmonary disease due to mycobacteria in the nonimmunocompromised population of British Columbia.

DESIGN: A retrospective cohort study of 110 cases of mycobacteria infection other than TB identified from 1991 to 1995.

SETTING: British Columbia Centre for Disease Control, Division of TB Control.

RESULTS: The overall incidence rate of infection with mycobacteria other than TB was 0.63×10-5/year. This incidence rate was significantly higher among women (relative risk [RR]=2, P=0.0006) and in those aged 55 years or older (RR=8, P<0.00001). In contrast with TB, patients were more frequently born in Canada (P<0.00001) or in industrialized countries other than Canada (P<0.00001), and were less likely to be Aboriginal (P=0.0007) or foreign born from Asia (P<0.0001). The most common organism isolated in British Columbia was Mycobacterium avium-intracellulare (82.7%). Overall, 78 (71%) cases had underlying lung disease. Drug intolerance was very common (42%). After treatment, 55% and 41% of the patients were rendered smear negative or culture negative, respectively. Radiological improvement was noted in 55% of patients, and 60% of patients responded symptomatically to treatment.

CONCLUSIONS: The overall incidence of pulmonary disease is low. It is a disease predominantly of women 55 years and older, and targets completely different ethnic groups than TB, suggesting a protective effect of infection with Mycobacterium tuberculosis. M avium-intracellulare was the most common pathogen isolated. Further investigation is required into the natural history of so-called 'colonizers'. Considerable morbidity may be prevented with earlier intervention.