Respiratory symptoms and lung function in a sample of Vermont dairymen and industrial workers.

This study reviews the respiratory status of a sample of Vermont male dairy farmers, and a comparison group from industry, matched for age, sex and smoking. Survey instruments included a standardized questionnaire and simple pulmonary function tests. In general, past and present smokers had more respiratory symptoms than never-smokers; and farmers, in all smoking categories, reported symptoms with greater frequency than did their counterparts from industry. Forced vital capacity (FVC) tended to be lower among men with a history of smoking but, within each smoking category, dairymen and factory workers had very similar FVCs. Farmers who had never smoked or who were current cigarette users had lower FEV1/FVC (forced expiratory volume at one second/forced vital capacity) ratios than their controls from industry. Sixteen diarymen demonstrated precipitins to either Micropolyspora faeni (13) or Thermoactinomyces vulgaris, (3), but only one reported a constellation of symptoms compatible with farmer's lung disease. The estimated prevalence of antibodies to thermophilic actinomyces in this farm population was approximately 10 per cent. Although sample sizes were limited, dairymen from small farms tended to be older, have more respiratory symptoms, less satisfactory pulmonary function, and more serologic evidence of exposure to farmer's lung antigens than their counterparts from large farms.

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.