Tom Volk's Fungus of the Month pages are very interesting. He gave Blastomycosis a repeat in 2007. Great background, some good pics, and more information.
"The ecological niche of this organism is uncertain due to infrequent isolation in nature. Only about 20 isolations have been made worldwide from nature. The first isolation was in Georgia along the Savannah River where 10 out of 356 samples tested positive. The location in nature is most often determined by the occurrence of disease. There is no skin test as with histoplasmosis which makes it difficult to determine who has been exposed to B. dermatitidis. We knon that Blastomyces generally grows in an acidic pH environment with high organic content --not necessarily in soil, although it seems to be most common along riverbanks. Lab experiments have found it is very sensitive to drying, although conidia release only when wetted. Reported cases of blastomycosis have occurred after rain of foggy weather. One theory states that B. dermatitidis cannot compete with the normal flora and can only grow in restricted environments."
Blasto: Tom Volk's Fungus of the Month