Abstract

TULAREMIA is primarily a zoonosis of considerable complexity in which over 100 vertebrate and invertebrate species act as reservoirs and/or vectors, with man being the most susceptible to infection.1 In humans, the disease can have a variable clinical course depending upon the site of inoculation of the causative organism, Francisella tularensis.1,2 History and clinical evaluation is of paramount importance in making the correct diagnosis because the organism is rarely obtained in culture except early in the course of the disease, and the diagnostic fourfold rise in antibody titer is usually not seen before three weeks.2 The organism is also not well demonstrated using conventional histochemical stains for bacterial organisms in tissue obtained at surgery or autopsy. Technics using direct immunofluorescence can be useful for identification of the organism and can be applied to either fresh or formalin-fixed tissue. The modified Dieterle spirochete technic has recently been successfully used in staining the bacterial agent causing Legionnaires disease.3 We recently found this stain to be useful in detecting F tularensis in autopsy material from a fatal case of tularemia. It is our purpose to briefly report the pathologic findings in this case of disseminated tularemia which had an unusual mode of transmission (cat to man) and to illustrate the usefulness of the modified Dieterle stain in demonstrating the organism in tissue.