Exposure to dust-borne bacteria in agriculture. II. Immunological survey.

In order to investigate whether high exposure to Erwinia herbicola causes sensitization in grain handlers, immunological tests (agargel precipitation, complement fixation, passive cutaneous anaphylaxis, and intradermal) with the extracts of these bacteria were performed in different groups of grain workers and in other groups of population. Tests with extracts of grain dust and other microorganisms were also performed. Grain workers showed in all the tests high incidence of positive reactions to E. herbicola, being significantly higher, as compared with unexposed subjects. Different actinomycetal and fungal extracts gave lower percentages of positive reactions. Skin reactions to E. herbicola were significantly correlated with the reactions to grain dust and showed a close relationship with the degree of exposure. The grain workers with respiratory symptoms reacted more frequently to E. herbicola than asymptomatic ones, both in intradermal and precipitation tests. Thus, these bacteria should be considered as a factor increasing risk of the respiratory disorders among grain handlers.