d2: systemic mycosis

characteristics of a systemic mycosis

found only in certain parts of the world

infection through inhalation of spores

production of tuberculosis-like lung infection

rarely disseminates into other parts of the body to cause severe disease

how is a systemic mycosis different from a cutaneous mycosis?

systemic: targets specific organs

cutaneous: limited to only the skin

is Histoplasma dimorphic? does it form spores?

dimorphic fungus

• growth in human tissue (37℃) = yeast form

• growth in soil (<35℃) = filamentous form

does form spores

how does infection of histoplasmosis happen? is it from the environment or other people?

Histoplasma capsulatum can be carried by bats and grows well in bat guano and bird droppings → decomposes the feces and forms spores

spores are produced and can be inhaled, entering the lungs

• fungi colonizes the lung: few or no symptoms in most cases

get into the macrophages + grow → cause inflammatory damage in the interior of the lungs as your body tries to fight them off

what happens in rare cases of a histoplasmosis infection?

becomes a chronic infection

• even more rarely, can invade and move to other parts of the body (disseminated) → can cause failure of the organ

chronic infections are more common in immune-compromised individuals

what disease is histoplasmosis often mistaken for?

tuberculosis

what are the symptoms of histoplasmosis?

cough, fatigue, fever

sometimes, granular lesions in the lungs → resembles tuberculosis

negative tuberculosis test

what role does geography play in diagnosis?

most infections are on the East Coast

if someone from the West Coast has histoplasmosis, you need to consider if they traveled to the east coast recently