Serum precipitins against microbes in mouldy hay with respect to age, sex, atopy, and smoking of farmers.

This study was based on a sample of 3,065 farmers from a larger survey population of 12,056 Finnish farmers. Data were collected in a postal survey conducted by the Social Insurance Institution of Finland. Serum samples for determination of precipitating antibodies were taken at local health centres. Precipitins were determined by the method of microplate immune diffusion. The antigen panel consisted of mycelial antigens of Micropolyspora faeni, Thermoactinomyces vulgaris, Aspergillus fumigatus, and Aspergillus umbrosus. Precipitins to any one of the four microbes were detected in 8.6% of the sera. The most common causes of positive precipitin tests were Aspergillus umbrosus and Thermoactinomyces vulgaris, which agrees with previous findings reported from Finland. In general, the precipitins were more prevalent among women, which corresponds to local cultural traditions, and in older farmers. The prevalence of precipitins did not differ between non-atopic and atopic (defined as past or present co-existence of atopic dermatitis including infantile eczema and/or hay fever or other allergic rhinitis) subjects. In contrast, the prevalence of precipitins was about 1.5-2 times larger among non-smokers than among smokers, which confirms the findings in previous reports. In future studies on occurrence of precipitins, the data should be controlled with respect to age, sex, and smoking.