Histoplasmosis

09/06/2013 by admin | Respiratory

Histoplasmosis:

Definition

a disease caused by the fungus Histoplasma capsulatum primarily affecting the lungs. Symptoms can be silent and asymptomatic. In acute infection symptoms are often no-specific and flu like in nature. Chronic histo can resemble TB.

P/c: HSM, lymphadenopathy, and adrenal enlargement. Lesions have a tendency to calcify as they heal.

Epidemiology

  1. United States: Ohio River valley and the lower Mississippi River
  2. Caves in southern and East Africa
  3. Eastern and central United States

 

Diagnostic tools/investigations

  1. sputum, blood
  2. infected organs
  3. detection of antigens in blood or urine samples

 

Aetiology

H. capsulatum grows in soil and material contaminated with bird or bat droppings (guano). The fungus has been found in poultry house litter, caves, areas harbouring bats, and in bird roosts (particularly those of starlings).

Pathophysiology

  1. The fungus is thermally dimorphic: in the environment it grows as a brownish mycelium, and at body temperature (37 °C in humans) it morphs into a yeast (DIMORPHIC: MyeceliumYeast)!
  2. The inoculum is represented principally by microconidia that, once inhaled into the alveolar spaces, germinate and then transform into budding yeast cells.

 

Hereditary? Infective? How does it spread?

  1. Histoplasmosis is not contagious, but is contracted by inhalation of the spores from disturbed soil or guano

 

Treatment and management (conservative/medical/surgical)

  1. Typical treatment of severe disease first involves treatment with amphotericin B, followed by oral itraconazole. 
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