NASAL AND OTOLOGIC EFFECTS OF EXPERIMENTAL INFLUENZA-A VIRUS-INFECTION

Past studies showed that experimental rhinovirus colds in adults resul ted in eustachian tube dysfunction and abnormal middle ear pressures. In the present study, the symptoms and pathophysiologic findings accom panying experimental influenza viral infection were documented. A tota l of 33 healthy adult volunteers were intranasally challenged with an influenza A/Kawasaki/86 (H1N1) virus and cloistered over a 9-day postc hallenge period to monitor for evidence of infection, signs and sympto ms of illness, and the extent and frequency of pathophysiologic respon ses of the nose, eustachian tube, and middle ear. Results showed a pro tective effect of high (greater than or equal to 16) prechallenge spec ific hemagglutination-inhibition antibody titer on the rate of infecti on and the magnitude and extent of provoked symptoms and pathophysiolo gic findings. Infected subjects with low (<16) prechallenge serum anti body titers (n = 21) developed significant respiratory illness. These subjects also had objectively measurable increases in nasal secretion production, and decreased nasal patency and mucociliary clearance rate s. More than 80% of the infected subjects developed eustachian tube dy sfunction, and approximately 80% had middle ear underpressures of less than -100 mm H2O on study days 4 and 5. Five of 21 infected subjects with low prechallenge antibody titers had otoscopic evidence of otitis media with effusion. These results support a causal role for viral up per respiratory tract infection in the pathogenesis of otitis media, p ossibly mediated by the early development of eustachian tube dysfuncti on and abnormal middle ear pressure.