Histoplasmosis, caused by the thermally dimorphic fungus Histoplasma capsulatum, is an uncommon multisystem disease with a global distribution. The spectrum of clinical manifestations ranges from an asymptomatic or minimally symptomatic acute pulmonary disease following inhalation of a large inoculum of Histoplasma microconidia to chronic pulmonary disease in patients with underlying structural lung disease. It also extends to acute progressive disseminated disease in patients with severe immunodeficiency. Generally, antifungal therapy is indicated for patients with progressive acute pulmonary histoplasmosis, chronic pulmonary histoplasmosis and acute progressive disseminated histoplasmosis. In immunocompetent patients, acute pulmonary histoplasmosis may be a self-limiting disease without the need for systemic antifungal therapy. Oral triazole antifungal drugs alone are recommended for less severe disease. However, moderate-to-severe acute pulmonary histoplasmosis requires intravenous amphotericin B therapy for at least 1–2 weeks followed by oral itraconazole for at least 12 weeks. For acute progressive disseminated histoplasmosis, intravenous amphotericin B therapy is given for at least 2 weeks (4–6 weeks if meningeal involvement) or until a patient can tolerate oral therapy, followed by oral itraconazole (or an alternative triazole) for at least 12 months. Chronic cavitary pulmonary histoplasmosis is treated with oral itraconazole for 1–2 years. There is insufficient evidence to support the use of isavuconazole or the echinocandins for the treatment of histoplasmosis.
Part of the book: Histoplasma and Histoplasmosis