Coccidioides immitis is a fungus that causes a disease known as coccidioidomycosis, or valley fever. It primarily thrives in arid regions, particularly in the southwestern United States, Mexico, and parts of Central and South America. The fungus is found in soil and can become airborne, leading to inhalation by humans and animals. Once inhaled, Coccidioides immitis can cause respiratory symptoms, ranging from mild flu-like signs to severe pneumonia. In some cases, it can lead to chronic illness or disseminated disease, affecting other parts of the body. Diagnosis typically involves laboratory tests, and treatment may include antifungal medications.