Stained light micrograph showing a tissue sample from a patient with blastomycosis, a disease caused by the fungus Blastomyces dermatitidis. Dark purple areas show higher concentration of cells indicative of inflammation in response to the infection. B. dermatitidis spores are found in soil and decaying plant matter in certain areas, and inhalation of these spores can cause infection. Blastomycosis tends to cause flu-like symptoms, but can also cause skin lesions. In severe cases of blastomycosis, the infection can spread from the lungs to other parts of the body, particularly in patients with weakened immune systems. Treatment typically involves a course of antifungal medication, lasting from 6 months to a year depending on the severity of the infection.