Pulmonary Histoplasmosis: A Clinical Update

Abstract

Histoplasma capsulatum, the etiological agent for histoplasmosis, is a dimorphic fungus that grows as a mold in the environment and as a yeast in human tissues. The areas of highest endemicity lie within the Mississippi and Ohio River Valleys of North America and parts of Central and South America. The most common clinical presentations include pulmonary histoplasmosis, which can resemble community-acquired pneumonia, tuberculosis, sarcoidosis, or malignancy; however, certain patients can develop mediastinal involvement or progression to disseminated disease. Understanding the epidemiology, pathology, clinical presentation, and diagnostic testing performance is pivotal for a successful diagnosis. While most immunocompetent patients with mild acute or subacute pulmonary histoplasmosis should receive therapy, all immunocompromised patients and those with chronic pulmonary disease or progressive disseminated disease should also receive therapy. Liposomal amphotericin B is the agent of choice for severe or disseminated disease, and itraconazole is recommended in milder cases or as “step-down” therapy after initial improvement with amphotericin B. In this review, we discuss the current epidemiology, pathology, diagnosis, clinical presentations, and management of pulmonary histoplasmosis.

Overview of invasive fungal infections in children in South America – the threat of resistant Candida species and the role of climate change in the new geographic distribution of endemic systemic mycosis

“…Histoplasmosis is an endemic fungal systemic infection that has been reported in all continents, except Antarctica [67 ▪▪ ,68 ▪▪ ], caused by the dimorphic fungus Histoplasma capsulatum [69–71] and it is present in a large part of Central and South America, including Brazil [67 ▪▪ ].…”

“…The clinical spectrum of this illness ranges from an asymptomatic, self-limited illness to a progressive disseminated disease; the disease prognosis depends on the host immune response, the fungal inoculum size inhaled, and the fungal virulence [67 ▪▪ ,71]. Transplacental, congenital and perinatal transmission of infections have also been reported.…”

“…The gold standard method for the diagnosis of histoplasmosis is the demonstration of the yeast-like H. capsulatum cells on microscopic examination of fluids and tissues; methods aiming to detect anti-Histoplasma antibodies or Histoplasma antigens are also available [67 ▪▪ ,71]. Treatment in adults with mild-to-moderate cases is usually unnecessary, though itraconazole should be given to patients with symptoms lasting over 1 month.…”

“…Treatment in adults with mild-to-moderate cases is usually unnecessary, though itraconazole should be given to patients with symptoms lasting over 1 month. In patients with moderately severe to severe acute pulmonary histoplasmosis, Amphotericin B intravenously for 1–2 weeks followed by itraconazole for a total of 12 weeks is recommended [67 ▪▪ ]. For children, the same recommendations apply [73].…”

Pulmonary endemic mycoses

“…Lifetime exposure rates can be nearly universal (90%) for those living in hyperendemic areas, such as the Mississippi and Ohio river basins in the USA and parts of Brazil. 6 Travel to Latin America has been associated with high (20%) exposure rates. 7 Acute pulmonary histoplasmosis is usually asymptomatic or a self-limiting influenza-like illness starting 3–21 days after exposure.…”