Dimorphic Fungal Pathogens
These are fungal infections of the body caused by fungal pathogens which can overcome the physiological and cellular defences of the normal human host by changing their morphological form. They are geographically restricted and the primary site of infection is usually pulmonary, following the inhalation of conidia.
Descriptions for the following fungi are provided.
- Blastomyces dermatitidis
- Coccidioides immitis/posadasii
- Histoplasma capsulatum
- Paracoccidioides brasiliensis
In the past microscopic morphology, conversion from the mould form to the yeast or spherule form, and animal pathogenicity have all been used for identification; however exoantigen tests are now the method of choice, at least for Blastomyces dermatitidis, Coccidioides immitis and Histoplasma capsulatum.
WARNING: RG-3 organisms. Cultures of these fungi represent a severe biohazard to laboratory personnel and must be handled with extreme caution in an appropriate pathogen handling cabinet.