FARMERS LUNG PRECIPITINS IN DOUBS (A DEPARTMENT OF FRANCE) - PREVALENCE AND DIAGNOSTIC-VALUE

In a French region where farmer's lung (FL) is common, we determined t he prevalence of FL precipitins in dairy farmers and analyzed the rela tion between the presence of FL precipitins and the clinical probabili ty of the disease. All the exposed dairy farmers of both sexes (n=2555 ) from five districts of the Doubs department were asked to respond to a medical and professional questionnaire. A total of 1763 (69%) farme rs agreed to participate. Precipitins tests were conducted in 551 (31% ) farmers who showed any respiratory symptom and in a random sample of 100 asymptomatic farmers. Serum for each farmer was analyzed by both double diffusion; and immunoelectrophoresis against Micropolyspora fae ni (MF) and extracts of moldy hay (HE) from Doubs. The 651 farmers wer e then divided into four groups (G 1-4) with a decreasing probability of FL (G1: typical FL symptoms; G4: asymptomatic farmers). The estimat ed prevalence of precipitins in the whole population was as follows: 1 ) by double diffusion, against HE: 83%, against MF: 27%; 2) by immunoe lectrophoresis, against HE: 26%, against MF: 19%. There was a close '' linear'' relation between the prevalence of precipitins detected by im munoelectrophoresis against HE and the symptoms: 51% in G1, 36% in G2, 29% in G3, and 13% in G4. Precipitins detected by immunoelectrophores is were also related to exposure and geography (more immunization in t ableland area than in plain or mountain area). Presence of precipitins detected by double diffusion was not related to symptoms, exposure, o r geography. This study shows that the prevalence of precipitins is hi gh in the exposed dairy farmers of Doubs, and suggests that immunoelec trophoresis (with the antigens used) is a more effective method for th e diagnosis of FL than double diffusion.