Blastomycosis

Blastomycosis or Gilchrist's disease is a fungal infection that is endemic to most of northern North America, although it can appear elsewhere. It is caused by the fungus Blastomyces dermatitidis dermatitidis, and is contracted when the fungus is breathed into the lungs from soil. From the lungs, it can spread through the rest of the body. It is particularly severe in patients who are immunocompromised.
Blastomycosis can present in a number of ways, from a mild case which present much like influenza and resolves itself within a few weeks, to Acute Respiratory Distress Syndrome (ARDS), which progresses quickly and is most often fatal if untreated.
Because of the similar symptoms, blastomycosis is often mistaken for histoplasmosis, another fungal disease.
Blastomycosis is not easy to confirm. It will often grow in blood cultures or sputum cultures, but will not necessarily do so. A lung biopsy is often definitive.
Blastomycosis at NIH
Blastomycosis at Wikipedia