17th February 2025

Histoplasmosis

Histoplasma is a fungus found in animal droppings in the Midwest and South-East USA, with particular prevalence around the Mississippi River. The disease is also prevalent in Mexico and Central America. 

In immunocompetent individuals, the disease is often asymptomatic, although 1-3 weeks after acquisition, patients may develop a self-limiting flu-like illness with bilateral alveolar shadowing and hilar/mediastinal lymphadenopathy on chest X-ray. Some cases may turn into chronic, cavitating disease. Disseminated disease can occur in the immunosuppressed. Adrenal insufficiency is a rare, life-threatening complication.

Gold-standard diagnosis involves Histoplasma seen either on microscopy or histopathology from biopsied tissue. Alternatively, diagnosis can be obtained via antigen testing. Oral itraconazole is the treatment.