Trends in asthma and hay fever in general practice in the United Kingdom 1976-83.

Weekly returns from the Royal College of General Practitioners research unit indicate that the attack rates for acute asthmatic episodes show a summer peak followed by an autumn peak in five out of the eight years studied, a summer peak alone in one year, and no discernible peak in two years. The autumn peaks coincide precisely with the rise in acute bronchitis attack rates, suggesting that autumnal asthma may be due to viral infections occurring against the background of bronchial hyperreactivity induced by summer pollen exposure. These data might also suggest that autumnal asthma is more likely to be diagnosed as acute bronchitis. Hay fever attack rates coincide with the rise in grass pollen counts, whereas the summer asthma peak is delayed by two to three weeks after the pollen peak.