Serum precipitins against microbes in mouldy hay with respect to the geographical location of the farm and to the work 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 gathered in a postal survey conducted by the Social Insurance Institution of Finland. Serum precipitins were determined by a microplate method of immune diffusion. The antigen panel consisted of mycelial antigens of Micropolyspora faeni, Thermoactinomyces vulgaris, Aspergillus fumigatus, and Aspergillus umbrosus. Geographical variation in the prevalence of precipitins was statistically significant, evidently due to climatic differences. The more intensive the cattle raising, the more commonly were precipitins found in the sera of farmers. For participation in animal tending (cattle, pigs, or poultry) or in plant cultivation work only, the prevalence of precipitins was largest among farmers who tended cattle or swine. According to earlier studies, serum precipitins to Thermoactinomyces vulgaris are associated with farmer's lung. Precipitins to this microbe were most commonly found in farmers who tended pigs and were also very common in farmers who worked only in plant cultivation. These findings imply that farmer's lung may also develop among pig farmers and grain producers. Precipitins to Thermoactinomyces vulgaris were clearly related to the type of grain drier used on the farm. The study failed to identify detailed tasks in farming associated with large prevalence of precipitins, probably owing to considerable overlap in the exposure encountered in different tasks.