Histoplasmosis

Histoplasmosis

Causative Agent

Histoplasma capsulatum; dimorphic fungus.

Morphology

Small oval yeast cell. 2-9 micrometre in diameter, packed with in cytoplasm of macrophages or monocytes.

Yeast phase formed culture at 37 degree Celsius.

Mycelial growth containing large spherical spores at 25 degree Celsius.

Source of Infection

In soil, fungus generate Candida which when present in air enter lung through inhalation.

In lung, they germinate into yeast like cells.

Human infection results from inhalation of spores.

Pathogenesis

Pathogen enters into reticuloendothelial system.

Develop pulmonary disease.

Fever

Anaemia

Ulcerative lesions may develop on skin or mucosa.

Laboratory Diagnosis

Specimen collection

Sputum, scrapping from skin lesions, lymph node and skin

Giemsa stained smear

Shows round to oval yeast cells present with macrophages.

Culture on SDA

Breached hyphae, round microconidia.

Treatment

Treated with Amphotericin.