According to the National Survey of Children in the United States, the prevalence of asthma was 15% (last 12 months), that of hay fever was 12.4%, of skin allergy 9.8% and digestive/ food allergy 3.6%. Overall, every fourth child is affected (25.4%). Regarding the diagnosis of asthma in children, the prevalence, for instance in Germany, rose from 1.25% to 2.21% between 1951–1952 and 1964–1965. For the last 10 years there has been dispute about whether the increase in asthma and allergy has come to a halt. However, the observation period is too short to draw any conclusion. A study of adults went beyond this simple dispute and investigated age and cohort effects for immunoglobulin E (IgE) sensitization from 1992 to 1998–2002. (more…)

Extrinsic allergic alveolitis (synonym: hypersensitivity pneumonitis) describes an interstitial and bronchioloalveolar disease of the lungs caused by an immune mediated hypersensitivity response. It is associated with repeated exposure to a variety of inhaled organic dusts and reactive chemicals (allergy chemical), but only a proportion of exposed subjects become affected. Notable examples are farmers’ lung (due to actinomycetes contaminating farm produce) and bird fanciers’ lung (due to secreted avian antigens). The disease has considerable potential as a model of allergic lung disease, since the populations at risk can often be identified precisely, the relevant antigens can be purified, and the clinical and immunologic consequences of antigen exposure can be examined. (more…)