German cattle allergy study (CAS): public health relevance of cattle-allergic farmers

Introduction Allergic reactions caused by animals are a common and significant occupational health concern. In a large population-based study on occupational asthma in Europe, farming has been among the occupations with the highest risk. Objectives Characteristics of cattle-allergic farmers are described in a retrospective observational design. Methods The study covers farmers from all regions of Germany which were reported to the Agricultural Institutions for Statutory Accident Insurance and Prevention (Landwirtschaftliche Berufsgenossenschaften, LBGs) between 1990 (January) and 2002 (December) with a suspected occupational cattle-allergic airways disease. For these farmers, the following parameters were considered: age, gender, onset of airways symptoms related to contact with cattle, begin of employment disability, total and specific Immunoglobulin E (IgE) against cattle allergens, and results of lung function measurements. Results A total of 513 patients (age 14-74, mean 40.7 years; 45.6% women, 54.4% men) had been reported for a suspected occupational cattle-allergic airways disease. Of these patients 24.8% showed cattle-related symptoms of asthma, 11.7% of rhinitis, and 60% of both asthma and rhinitis, while only 34.5% of all reported patients showed an airways obstruction in the first documented lung function test. A total of 62.5% out of the group of patients with an officially recognized occupational disease (42.1%, n = 216) have an initial employment disability with a rating of 20% or above. Conclusions Our results underline the high public health relevance of cattle allergy in farmers, especially in the light of the large number of young patients. Considering the known difficulties in diagnosing cattle allergy due to the number of false negative test results, we are convinced that its relevance is even higher than the number of reported cases suggests. The high rate of initial employment disability among the affected patients underlines the need for improved preventive measures.