PNEUMONIA SYMPTOMS?
WHEN TO CONSIDER HISTOPLASMOSIS TESTING
You live in or have recently traveled to an area affected by histoplasmosis*
+
You have respiratory symptoms suggestive of pneumonia (such as fever, chills, cough, shortness of breath, chest pain, and fatigue)
Fever
Chills
Cough
Shortness of Breath
Chest Pain
Fatigue
*The areas potentially affected by Histoplasma continue to expand. See Dr. Spec’s commentary.
Consider asking about fungal testing for:
Consider Histoplasmosis Testing if Symptoms
Persist Despite a Course of Antibiotics
You live in or have recently traveled to an area affected by histoplasmosis
+
You have respiratory symptoms suggestive of pneumonia
+
Your pneumonia symptoms persist
after at least one course of antibiotics given without confirmation of a bacterial infection (empiric therapy).
↓
You should be tested for Histoplasma before another course of antibiotics.
Consider Histoplasmosis Testing for High Exposure Risk
or Suspicious Clues
You live in or have recently traveled to an area affected by histoplasmosis
+
You have respiratory symptoms suggestive of pneumonia
+
↓
You should be tested when you first see a healthcare provider for your
symptoms.
HOW DOES TESTING USUALLY WORK?
Urine enzyme-immunoassay (EIA) antigen testing
- What it’s Testing For: Fungal antigen (fungal material that is shed into the urine and recognized by the test)
- 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 (part of the immune response): Antibodies to Histoplasma
- Advantages:
- The test is very specific and simple (can help rule out Blastomyces)
- Provides a yes/no answer
- Disadvantages:
- Will often turn positive with previous infections that are no longer active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- Will often turn positive with previous infections that are no longer active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 (taking a washing of the lung to try and grow fungus on a plate) 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.