The Tecumseh study of respiratory illness. X. Relation of acute infections to smoking, lung function and chronic symptoms.

The relationship of acute respiratory illness and infection to chronic bronchitis was investigated in the community of Tecumseh, Michigan. Families were randomly selected for study from among all those in the community and they were followed for periods of one year. Occurrence of acute respiratory illnesses was identified on a weekly basis. Frequency of chronic symptoms of cough and sputum production was separately ascertained. Lung function studies were performed three times during the course of the surveillance year and blood specimens were collected at those times. The blood specimens were tested for rise in antibody titer with antigens of type A and B influenza, respiratory syncytial virus and Mycoplasma pneumoniae. Adults with mild or intermittent chronic symptoms of cough and sputum production experienced more acute respiratory illness than those without these symptoms. This finding was present at different levels of smoking frequency. A similar relationship was present when serologic infection rates were used in the analysis instead of acute illness incidence. When the population was dichotomized on the basis of lung function data, the segment of the population with more depressed values was found to have experienced higher infection rates. The results suggest that acute infection may play an independent role in the pathogenesis of chronic respiratory disease.