Blastomycetes are a group of fungi that belong to the phylum Ascomycota. They are known for their ability to cause infections in humans and animals, particularly in immunocompromised individuals. One of the most notable species is Blastomyces dermatitidis, which can lead to a disease called blastomycosis, primarily affecting the lungs and skin. These fungi thrive in moist, organic-rich environments, such as soil and decaying wood. Infection typically occurs when spores are inhaled, leading to respiratory symptoms. Early diagnosis and treatment are crucial, as untreated blastomycosis can result in severe health complications.