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 faen i (MF) and extracts of moldy hay (HE) from Doubs. The 651 farmers were then divided into four groups (G 1-4) with a decreasing probability o f FL (G1: typical FL symptoms; G4: asymptomatic farmers). The estimate d prevalence of precipitins in the whole population was as follows: 1) by double diffusion, against HE: 83%, against MF: 27%; 2) by immunoel ectrophoresis, against HE: 26%, against MF: 19%. There was a close ''l inear'' relation between the prevalence of precipitins detected by imm unoelectrophoresis against HE and the symptoms: 51% in G1, 36% in G2, 29% in G3, and 13% in G4. Precipitins detected by immunoelectrophoresi s were also related to exposure and geography (more immunization in ta bleland area than in plain or mountain area). Presence of precipitins detected by double diffusion was not related to symptoms, exposure, or geography. This study shows that the prevalence of precipitins is hig h in the exposed dairy Farmers of Doubs, and suggests that immunoelect rophoresis (with the antigens used) is a more effective method for the diagnosis of FL than double diffusion.