Farmer's lung disease in Vermont.

Several Vermont population groups were surveyed for the occurrence of antibodies to thermophilic actinomycetes. Antibodies to M. faeni and T. vulgaris were measured by the precipitin method in all subjects and, in 124 subjects, M. faeni antibodies were also measured by the indirect fluorescent antibody (IFA) technique. There was relatively good correlation between the two techniques (r 0.48, p less than 0.01). Hospital employees, blood donors and patients with chronic bronchitis were generally negative for precipitins to thermophilic actinomycetes. Of the 258 Vermont dairy farmers surveyed, 14 (5.4%) had precipitins to M. faeni, 3 (1.2%) had precipitins to T. vulgaris but only 1 farmer with antibodies to M. faeni had symptoms of possible farmer's lung disease (FLD). On the other hand, 10 (4.1%) precipitin-negative farmers had symptoms possibly consistent with FLD. The IFA test did not correlate any better with symptoms. 7 (5.6%) patients with pulmonary fibrosis had precipitins to M. faeni 5 of these were diagnosed as having FLD. 18 (14.4%) had precipitins to T. vulgaris and only 3 of these patients were felt to have hypersensitivity pneumonitis. Patients with pulmonary fibrosis and FLD hat IFA titers of greater than or equal to 1/128, but so did asymptomatic farmers.