Microbiological evolution of hay and relapse in patients with farmer's lung.

BACKGROUND Recent studies in France have shown that Absidia corymbifera and, to a lesser degree Eurotium amstelodami and Wallemia sebi, play a role in farmer's lung disease (FLD), but that Saccharopolyspora rectivirgula, classically incriminated, does not. Little is known about farmers' reactions to these fungi or the circumstances which lead to exposure. AIMS To investigate the conditions which favour the development of these microorganisms in hay and to analyse the relation between their concentration and the risk of occurrence of FLD. METHODS Sequential microbiological analyses of each batch of hay stored in 10 farms at risk for FLD and a serological survey of 10 farmers (five with a past history of FLD). RESULTS Exposure to microorganisms varied widely according to farms and periods. These microorganisms usually reached a peak in January and proliferated when harvesting conditions favoured excessive humidity in hay (rain during harvest, soil in the hay). Three of the five FLD patients presented with FLD respiratory recurrence and positive serology for A corymbifera during the winter (2000-01), after exposure to a significantly higher amount of A corymbifera than other farmers. Similar, but less significant, results were found for E amstelodami exposure, but not with W sebi. CONCLUSIONS Results contribute to confirming A corymbifera as a major aetiological agent of FLD in Doubs, and encourage further studies with a view to implementing preventive measures.