Blastomytosis ???

Spent some time with our daughter and her family this week and their trusty dog, Marsh.
Sad to say, Marsh has Blastomytosis. I really don't understand the disease, but I do know it is devastating to see what it can do. I've seen a healthy, robust critter completely deteriorate in just a few weeks. They say it is caused from spores in the soil. How do you keep a dog from romping along the shoreline? Impossible!
The poor dog has difficulty eating and has open sores throughout the body. He is just skin and bones. It is so very sad!
How come we never heard of this sort of thing before? The plants and water along lakes, rivers and streams have always attracted critters to it's shore. Why all of a sudden do animals and humans get this new disease. Is it so new?
Our neighbors had it when they raked leaves along the shoreline. What on earth is growing in the soil? A friend's father had it from using sludge from a pond, to put in his garden as fertilizer. Spores scatter in the wind and I wonder if this could infect a whole lakeside neighborhood; humans and critters, alike. Children do play in sand when swimming at a beach!
I would appreciate any information on this.