This explains why blastomycosis is often found in small pockets instead of being widespread. The proximity to water appears to be very important. Blastomycosis has a well-defined endemic area where it is found. The area includes the Mississippi, Missouri, and Ohio River valleys, the Mid-Atlantic States and parts of Quebec, Manitoba, and Ontario. It is believed that the range of blastomycosis continues to grow.
Blastomycosis is primarily a disease that infects people and dogs.
While there have been reported cases in a wide variety of animals including cats, horses, and ferrets, they are relatively rare. While humans often become infected, dogs are still 10 times more likely to develop the disease than people are. A big factor in determining which dogs or people get infected is directly related to their lifestyle and where they live. People that spend time in the woods, as well as their dogs are much more likely to become infected. If they travel in swamps or near water they are at an even greater risk.