Fundamental medical mycology is the specialized study of pathogenic fungi and the diseases (mycoses) they cause in humans and animals . While thousands of fungal species exist in nature, fewer than 100 are regularly identified as human pathogens. This field has grown in critical importance due to the rise of opportunistic infections in immunocompromised patients and the emergence of rare, previously unreported fungi. Core Concepts in Medical Mycology Fundamental Medical Mycology - CDC