Respiratory virus infection in chronic chest disease.

This thesis describes the impact of respiratory virus infections in patients with chronic chest disease and investigates the role of influenza vaccine and the possibility of preventing infection with intranasal interferon. The thesis begins by defining respiratory virus infection and presenting a brief historical introduction. This is followed by an account of the important respiratory viruses, the major causes of chronic chest disease and the relationship between respiratory virus infections and exacerbations of chest disease. The introduction concludes by describing the nature of interferons and reviews clinical trials of interferon therapy. The subjects, materials and methods are followed by the results of the clinical and laboratory studies. Respiratory virus infections were significantly more severe in adults with chronic chest disease than in previously healthy individuals. Unfortunately prophylaxis with intranasal interferon was not associated with any benefit. A preliminary study in children with cystic fibrosis showed that rhinoviruses were associated with exacerbations of lung disease. A survey of General Practitioners in the Trent Region revealed that less than 20% of susceptible patients were vaccinated against influenza and identified several factors which were associated with improved vaccination rates. A study in patients with asthma found that only 9% had received influenza vaccine prior to the 1989-90 influenza epidemic. Influenza vaccination was not associated with any significant reduction in the proportion of asthmatic patients who developed influenza-like symptoms during the influenza outbreak and many episodes of illness were thought to have resulted from other respiratory viruses. All studies suffered from difficulties in establishing a diagnosis of respiratory virus infection, with viruses isolated from less than 15% of acute nasopharyngeal swabs and fewer than 25% of paired serum samples showing a significant antibody rise. The implications of the results and future possibilities are discussed.