Environmental mycobacteria in Ireland as a source of non-specific sensitisation to tuberculins

The environment of 16 farms in counties Clare, Cork and Donegal where persistently high incidence of non-specific tuberculin reactions occurred was examined for mycobacteria. Of 190 samples of moss, 37 samples of water and 13 samples of soil, 59 strains of slowly growing and 36 strains of rapidly growing mycobacteria weve isolated and randomly tested for the ability to provoke a non-specific reaction to bovine and avian tuberculin. The majority of slowly growing mycobacteria, especially the recently isolated new species Mycobacterium hiberniae, were capable of inducing non-specific reactions to tuberculin when administrated parenterally or orally. In Ireland, the bryophytes Hylocomium splendens, Thuidium tamariscinum, and Breutclia chrysocoma are common in cattle pastures and are rich sources of mycobacteria. Ingestion of large amounts of moss was observed when cattle grazed low vegetation on winterage.