Histoplasmosis

Histoplasmosis

Histoplasma capsulatum

Dimorphic fungus, macro- and micronidia, siderophores to scavenge iron, intracellular macrophage parasite, requires cellular immunity for clearance

Enviroment; soil that contains bird or bat droppings

Respiratory tract

Inhaled spores (microconidia)

1-3 weeks

Inhaled microconidiacolonize lung as yeast. Macrophage phagocytize yeast but can’t yill them. Other immune cells are recruited and form granulomas with infected cells and fungi at the center. Systemic infection can result in immune compromised hosts

Respiratory infection- sometimes asymptomatic, resolves within 2 weeks but may last 3-5 weeks, flu-like symptoms

Chronic pulmonary infection, fibrosis, cavitary lesions, Dissemination to other tissues- mortality 4-8% of hospitalized individuals

Avoid exposure, wear a mask if exposure is likely, spray 3% formalin on guano deposits, prophylaxis with itraconazole for immune-compromised

Symptoms may go away without treatment, antifungal medication- itraconazole for 3-12 months