Precipitating antibodies towards antigens associated with farmer's lung disease were studied in Finnish dairy farming and non-farming rural populations and the results were compared to those of serum samples of patients suspected of having a fungal allergy. The antigen panel consisted of Aspergillus fumigatus, Micropolyspora faeni and Thermoactinomyces vulgaris. All three microbes seemed to be important environmental inducers of antibody formation. The prevalence of antibodies towards all of them was higher in the patient group. The presence of A. fumigatus and T. vulgaris antibodies correlated best with the occurrence of respiratory disease. The difference in M. faeni antibody prevalence between patients and the control group was less significant.
The results suggest that in Finland the relative importance of those microorganisms associated with farmer's lung disease may be different from that reported from other countries.