Viruses as Precipitants of Asthmatic Attacks in Children

Evidence for the exacerbation of asthma by specific infectious agents was sought in an October 1971 through May 1972 outpatient study of 16 children with histories of wheezing associated with apparent symptomatic respiratory infections (SRI). Clinical data were collected daily, and pharyngeal and nasal specimens were obtained routinely for microbiological analyses. Subjects experienced 61 episodes of asthma, and 42 of these were coincident with an apparent SRI. Asthmatic attacks occurred with 38 of 49 severe SRI, but only 4 of 22 mild SRI were similarly associated. Asthma was precipitated during 21 of 23 severe SRI of viral origin, but in only one of six severe SRI of bacterial origin. Fourteen of 15 rhinovirus infections that resulted in severe SRI and all episodes of A2/Hong Kong influenza were associated with attacks of asthma. No asthma was noted during episodes of asymptomatic virus shedding.