Fatal-cat trasmitted tularemia: demonstration of the organism in tissue.

The case reported represents an unusual mode of transmission of tularemia from cat to man, with fatal outcome. The use of the modified Dieterle spirochete stain demonstrated F tularensis in tissue when all other routine stains failed. Direct immunofluorescent staining confirmed the presence of the organism in tissue sections. F tularensis and the etiologic agent of Legionnaires' disease are similar only in their ability to stain with the modified Dieterle stain and their inability to stain with conventional histochemical technics.