Background: Esparto is one the most frequent causes of hypersensitivity pneumonitis in Spain.

Objective: Determination of risk factors in the working environment that could explain the sensitisation process, and assessment of the differences in specific IgG levels to Aspergillus fumigatus, Saccharopolyspora rectivirgula and Thermoactynomices vulgaris in patients with hypersensitivity pneumonitis induced by esparto, exposed healthy
plasterers and control population.

Methods: Determination of precipitins and specific IgG to Aspergillus fumigatus, Saccharopolyspora rectivirgula and Thermoactynomices vulgaris in the three previously mentioned groups. Questionnaire on possible risk occupational and extra-occupational factors.

Results: Both healthy and exposed plasterers have higher levels of specific IgG to Aspergillus fumigatus, Saccharopolyspora rectivirgula and Thermoactynomices vulgaris than the healthy controls. The patients had higher levels of IgG than exposed healthy plasterers only to Thermoactynomices vulgaris. Precipitins were detected in only two patients. There were no occupational factors influencing on the sensitisation process.

Conclusions: Specific IgG is an occupational exposure marker among plasterers, but it has not been possible to establish a cut off point that differentiates exposed subjects from affected ones. This determination has a greater sensitivity than precipitins. We did not identify occupational or extra-occupational risk factors that facilitate the sensitisation process.

Key words: Hypersensitivity pneumonitis, precipitins, Saccharopolyspora rectivirgula, Specific IgG, Thermoactynomices vulgaris