Mycobacterium tuberculosis infection and the subsequent development of asthma and allergic conditions

Background: Epidemiologic studies have suggested that certain viral infecti ons, as well as exposure to Mycobacterium tuberculosis in early Life, could , at least to some extent, prevent the subsequent development of atopic dis ease. Objective: We investigated whether M tuberculosis infection in childhood or adolescence has any effect on the development of asthma and allergic condi tions in later Life. Methods: The study subjects (n = 1162) were individuals notified to the Nat ional Tuberculosis Registry between January I, 1966, and December 31, 1969, who were 20 years of age or younger and had verified or justifiably probab le new active tuberculosis of respiratory or other organs. The control subj ects were age-matched, sex-matched, and geographically matched control pair s from the Population Registry of the Social Insurance Institution in Finla nd, The subjects were followed for 28 to 32 years. The prevalence of persis tent asthma and allergic conditions among men and women at the end of 1997 were calculated on the basis of the Drug Reimbursement Registry of the Soci al Insurance Institution in the whole study population and in the subgroup of subjects aged 16 years or younger at the time of M tuberculosis infectio n. Results: In women a significantly lower prevalence of persistent asthma was found among those aged 16 years or younger at the time of M tuberculosis i nfection than among the control subjects (3.7% vs 8.3%, respectively; P = . 035), The women with a history of tuberculosis also showed a significantly lower prevalence of allergic conditions than the control subjects (8.3% vs 14.0%, respectively; P = .003) when the whole study population of women was considered. In men, however, the only significant difference between the c ases and control subjects was found for persistent asthma, with the cases s howing a significantly higher prevalence than the control subjects (4.4% an d 1,8%, respectively; P = .008). Conclusion: M tuberculosis infection in childhood significantly reduced the occurrence of subsequent asthma in women. Moreover, this infection was als o found to reduce the occurrence of allergic conditions in later hfe in wom en. By contrast, no suppressive effect of M tuberculosis infection in child hood or adolescence on the later development of asthma or allergic conditio ns could be observed in men. The differences in the natural history of atop ic disease between the sexes and the occurrence of tuberculosis mostly in l ater childhood and adolescence may largely explain our findings.