PNEUMONIA SYMPTOMS?

WHEN TO CONSIDER HISTOPLASMOSIS TESTING

You live in or have recently traveled to an area affected by histoplasmosis* AND

*The areas potentially affected by Histoplasma continue to expand. See Dr. Spec’s commentary.

Fever

Chills

Cough

Shortness of Breath

Chest Pain

Fatigue

You have respiratory symptoms suggestive of pneumonia (such as fever, chills, cough, shortness of breath, chest pain, and fatigue) AND

SCENARIO 1: HIGH EXPOSURE RISK PLUS OTHER CLUES

You’ve had lots of exposure to bird or bat droppings or a demolition or remodeling project. OR

Your chest X-ray mentions new nodules or lymphadenopathy. OR

You have been linked to a known histoplasmosis outbreak.

You should be tested when you first see a healthcare provider for your illness.

SCENARIO 2: YOU HAVE EXPOSURE RISK AND PERSISTENT SYMPTOMS

Your pneumonia symptoms persist after at least one round of antibiotics given without confirmation of a bacterial infection (empiric therapy).

You should get tested for histoplasmosis before getting another round of antibiotics.

HOW DOES TESTING USUALLY WORK?

Urine enzyme-immunoassay (EIA) antigen testing

  • Source: Urine
    • Fast, yes/no results (quick turnaround time)
  • Disadvantages
    • Can also react with the fungus that causes blastomycosis (but this is usually ok because they are treated similarly)
    • Can be negative early in the disease

Serum Test for Antibodies

Immunodiffusion

Source: Blood

  • What it’s testing for: Antibodies to the Histoplasma
  • Advantages:
    • The test is very specific and simple (can help rule out Blastomyces)
    • Provides a yes/no answer
  • Disadvantages:
    • Will sometimes turn positive with previous infections that are no longer active

 

Complement fixation  (CF)

Source: Blood

  • What it’s testing for: Antibodies to Histoplasma, provides a numeric result
  • Advantages:
    • Picks up most cases
    • Helps distinguish from Blastomyces infections
  • Disadvantages:
    • Long turnaround time
    • Will sometimes turn positive with previous infections that are no longer active

Other Testing:

Beyond additional imaging studies, other tests are also sometimes used to test for histoplasmosis. For example, patients who have lung nodules may have those sampled and tested via culture and to look at it under the microscope (particularly when there is a concern for lung cancer). Sometimes, your doctors may order testing on sputum or a lung washing, although this is not done that frequently. For a discussion of these tests, please see Testing Algorithm for Histoplasmosis.