This study supports the hypothesis that upper respiratory viral infections are associated with 80-85% of asthma exacerbations in school age children.

We have shown that viruses are associated with 80 to 85% of asthma exacerbations in school-age children in the community. We hypothesize that viral infections are also associated with severe attacks of asthma precipitating hospital admissions. To investigate this, we conducted a time-trend analysis, comparing the seasonal patterns of respiratory infections and hospital admissions for asthma in adults and children. During a 1-yr study in the Southampton area of the United Kingdom, 108 school-age children monitored upper and lower respiratory symptoms and took peak expiratory flow rate (PEFR) recordings. From children reporting a symptomatic episode or a decrease in PEFR, samples were taken for detection of viruses and atypical bacteria. A total of 232 respiratory viruses and four atypical bacteria were detected. The half-monthly rates of upper respiratory infection were compared with the half-monthly rates for hospital admissions for asthma (International Classification of Diseases [ICD] code 493) for the same time period for the hospitals serving the areas from which the cohort of schoolchildren was drawn. The relationships of upper respiratory infections and hospital admissions for asthma with school attendance were studied. Strong correlations were found between the seasonal patterns of upper respiratory infections and hospital admissions for asthma (r = 0.72; p < 0.0001). This relationship was stronger for pediatric (r = 0.68; p < 0.0001) than for adult admissions (r = 0.53; p < 0.01). Upper respiratory infections and admissions for asthma were more frequent during periods of school attendance (87% of pediatric and 84% of total admissions), than during school holiday periods (p < 0.001). These relationships remained significant when allowance was made for linear trend and seasonal variation using multiple regression analysis (p < 0.01). Not surprisingly, school attendance, because it is a major factor in respiratory virus transmission, was found to be a major confounding variable in children. This study demonstrates that upper respiratory viral infections are strongly associated in time with hospital admissions for asthma in children and adults. Rhinoviruses were the major pathogen implicated, and the majority of viral infections and asthma admissions occurred during school attendance.

Background-Acute lower respiratory tract illness in previously well adults is usually labelled as acute bronchitis and treated with antibiotics without establishing the aetiology. Viral infection is thought to be the cause in most cases. We have investigated the incidence, aetiology, and outcome of this condition. Methods-Previously

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Currently, the diagnosis of human respiratory coronavirus infection is either slow or insensitive. This paper describes nested polymerase chain reaction assays for the detection of human coronaviruses OC43 and 229E. The specificity and sensitivity of the assays have been determined and they have been applied to the detection of the viruses in nasal aspirates. These assays are more rapid and sensitive than cell culture and may replace the latter as the diagnostic method of choice.