Inverse association between Mycobacterium tuberculosis infection and atopic rhinitis in children.

The association between Mycobacterium tuberculosis (MTB) infection and atopy remains controversial. To investigate the association between MTB infection and atopic rhinitis in children living in a high TB incidence area. In this cross-sectional study 418 children aged 6–14 years from an established epidemiological research-site in a poor urban community were invited to participate. They were assessed for allergic rhinitis (ISAAC questionnaire) and skin responses to tuberculin and eight environmental allergens. The presence of a BCG scar was documented, intestinal parasites and total and Ascaris lumbricoides-specific IgE levels were measured. Atopic rhinitis was defined, using the new World Allergy Organization (WAO) definition, as reported allergic rhinitis and a positive skin prick test (SPT ≥3 mm) to any allergen. Among the 337 children enrolled 10.4% had allergic rhinitis, 17.5% a positive SPT and 53% a positive tuberculin skin test (TST ≥10 mm). Children with a positive TST were significantly less likely to have recent atopic rhinitis (ORadjusted 0.06; 95% CI 0.007–0.5) than those with a negative TST. SPTs were significantly more common in children with negative TST who had recent allergic rhinitis (ORadj 34.0; 95% CI 7.6–152.6), but not in children with positive TST and recent allergic rhinitis (ORadj 0.6; 95% CI 0.07–5.2). MTB infection seems to reduce the prevalence of atopic rhinitis, and influences SPT reactivity in children with allergic rhinitis from a high TB incidence area. [ABSTRACT FROM AUTHOR]