Endemic Mycoses: Learning Outcomes

Coccidioidomycosis, commonly known as San Joaquin Valley fever, is a fungal disease caused by Coccidioides immitis or Coccidioides posadasii. When Coccidioides spores are inhaled, they transform into spherules that result in infection. Coccidioidomycosis is also a common cause of community-acquired pneumonia and can cause severe disease in the immunocompromised. Patients may present with fever, chills, cough, chest pain, and shortness of breath. The diagnosis is supported by clinical history, radiology, microscopy, fungal culture, and serological data. Management involves antifungals and supportive care. In severe disease, addressing the etiology of immunosuppression is critical.

Histoplasmosis is an infection caused by Histoplasma capsulatum, a dimorphic fungus. The fungus exists as a mold at low temperatures and as yeast at high temperatures. H. capsulatum is the most common endemic fungal infection in the US and is most prevalent in the midwestern and central states along the Ohio and Mississippi River valleys. Transmission is through inhalation, and exposure to soils containing bird or bat droppings increases the risk of infection. Most infections are asymptomatic; however, immunocompromised individuals generally develop acute pulmonary infection, chronic infection, or even disseminated disease. Diagnosis is via different modalities, with the visualization and/or growth of the causative organism made using direct microscopy, histopathology, or culture studies. Management is dependent on disease severity. The antifungal medications that are used include amphotericin B and itraconazole.