Serology of respiratory viruses in relation to asthma and bronchial hyperresponsiveness.

Do individuals with serological evidence of infections with respiratory viruses have an increased prevalence of asthma or bronchial hyperresponsiveness (BHR)? Antibodies to four common respiratory viruses were measured in the sera of 81 subjects without a history of a recent respiratory infection. The subjects underwent an interview, spirometry, a methacholine provocation test and skin prick tests. In sera where virus antibodies were found, IgG titer values of > or = 1:40 were regarded as evidence of a recent infection. A significant relationship was found between serological markers of a recent respiratory syncytial (RS) virus infection and physician diagnosed asthma (odds ratios (OR) 14.5, 95% confidence intervals (CI) 1.4-151) or BHR (OR 12.7, 95% CI 1.2-132)(p < 0.05). Furthermore, the total blood eosinophil count was significantly higher in subjects with serological signs of a current or recent RS virus infection than in those without such signs (364 +/- 198 x 10(6)/L and 175 +/- 118 x 10(6)/L respectively, p < 0.05). In conclusion, a recent RS viral infection may be an important factor in the induction of symptoms and signs suggestive of asthma.