HISTOPLASMA

Question 1

What is a strain of Histoplasma?

Answer 1

H. Capsulatum

Question 2

What kind of pathogen is Histoplasma (H. Capsulatum)?

Answer 2

Dimorphic (two different forms) fungi
-grows as yeast & mold

Question 3

What is the epidemiology/reservoir for Histoplasma (H. Capsulatum)?

Answer 3

Feces in soil
Common in Ohio/Mississippi River valleys, Caribbean, Mexico
-Bat and Chicken/bird poop (guano- accumulated feces of bats used as fertilizer)

Question 4

Why is it important to take a thorough history in order to diagnose Histoplasma (H. Capsulatum) infection?

Answer 4

The disease can progress rapidly and cause chronic effects if not caught and treated quickly
-important to ask if traveled to high risk regions
-important to ask about exposure to bats

Question 5

What is the pathogenesis of Histoplasma (H. Capsulatum)?

Answer 5

Inhalation of microconidia (spores)

Question 6

How would a Histoplasma (H. Capsulatum) infection present?

Answer 6

Pulmonary: often asymptomatic/self limiting yet can progress and become more severe

Disseminated (spread): usually occurs in immunocompromised (HIV, medications, immune deficits)

Sub-acute (rapid change):
-Cavitary lung disease (gas pockets in lungs)
-Lung nodules,
-Mediastinal fibrosis (fibrotic tissue forms in the mediastinum and can compress vital organs)
-Granulomatous disease (can make WBCs/immune cells less effective and makes someone more vulnerable to disease)

Question 7

How can you diagnose a Histoplasma (H. Capsulatum) infection?

Answer 7

-Culture of sputum, blood, tissue biopsy
-Stains
-Serology (most helpful with subacute/chronic)
-Urine Histoplasma antigen test

Question 8

How would you treat a Histoplasma (H. Capsulatum) infection?

Answer 8

Pulmonary treatment:

mild- no treatment unless symptoms do not resolve in 1 month/patient is immunocompromised

moderate/severe/immunocompromised- Liposomal Amphotericin B followed by Itraconazole

Disseminated (spreading infection) treatment:

mild/moderate- Intraconazole

moderate/severe- Liposomal Amphoteracin B followed by Itraconazole