Nasal and otologic effects of experimental respiratory syncytial virus infection in adults

Purpose: Upper respiratory tract viral infections continue to cause substantial patient morbidity and complications including sinusitis, otitis media, and pneumonia. This study was conducted to more clearly define the extent and frequency of nasal and otologic effects of respiratory syncytial virus infection in healthy adult volunteers. Materials and Methods: Thirty-two healthy, susceptible adult volunteers were cloistered for a 9-day period. During this time, subjects underwent nasal inoculation with respiratory syncytial virus. Monitoring included daily self-assessment of general health, as well as nasal and otologic symptoms. Objective measurements of nasal and otologic function included expelled nasal secretion weight, saccharin-dye mucociliary clearance, sonotubometry, tympanometry, and physical examination. A nasal lavage was done each morning, and fluids were submitted for viral detection. Twenty-one days after viral inoculation, all subjects had convalescent blood samples drawn for assay of virus-specific antibody titres. Results: Eighteen subjects (56%) became infected with the challenge as determined by either viral shedding (47%) or antigen detection (41%) from the nose or a 4-fold rise in virus-specific antibody titer (34%). Infected subjects more frequently reported adverse nasal (congestion, rhinorrhea) and general symptoms (fever, malaise, illness). By day 6, only 46% of infected subjects had normal middle ear pressure (> - 100 mm H₂O). Nasal secretion also increased substantially after infection. No patterned changes in mucociliary clearance or sonotubometry occurred, and no subjects developed otitis media. Conclusions: Nasal inoculation of healthy, susceptible adult volunteers with respiratory syncytial virus results in detectable infection in only about half of the subjects challenged. Infected subjects experience substantial symptoms and signs of a viral upper respiratory tract illness. As in our previous studies using rhinovirus and influenza A virus, respiratory syncytial virus disrupted the maintenance of normal middle ear pressures. These findings provide further support for the relationship between viral upper respiratory tract infections and otitis media.