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Introduction ⬇

Certain fungal species are associated with human respiratory diseases acquired by inhaling spores from sources such as dust, soil, and bird droppings. Serologic tests may be used for diagnosis. Fungal diseases are categorized as either superficial or deep. For the most part, superficial mycoses are limited to the skin, mucous membranes, nails, and hair. Deep mycoses involve the deeper tissues and internal organs. Histoplasmosis, coccidioidomycosis, and blastomycosis are caused by deep mycoses.

These tests detect serum precipitin antibodies and CF antibodies present in the fungal diseases of coccidioidomycosis, blastomycosis, and histoplasmosis. Coccidioidomycosis, also known as desert fever, San Joaquin fever, and valley fever, is contracted through inhalation of Coccidioides immitis spores found in dust or soil. Blastomycosis is caused by infection with organisms of the genus Blastomyces. Histoplasmosis is a granulomatous infection caused by Histoplasma capsulatum.

Normal Findings ⬆ ⬇

Procedure ⬆ ⬇

  1. Collect a 7-mL blood serum sample in a red-topped tube. Observe standard precautions.

  2. Label the specimen with the patient’s name, date, and test(s) ordered and place in a biohazard bag for transport to the laboratory.

Clinical Implications ⬆ ⬇

  1. Antibodies to Coccidioides, Blastomyces, and Histoplasma appear early in the course of the disease (weeks 1–4) and then disappear.

  2. Negative fungal serology does not rule out the possibility of a current infection.

  3. CF titers ≥1:8 are considered presumptive of infection.

Interventions ⬆ ⬇

Pretest Patient Care

  1. Explain test purpose and procedure.

  2. Follow guidelines in Chapter 1 for safe, effective, informed pretest care.

  3. Specimens for culture of the organism may also be required.

Posttest Patient Care

  1. Review test results; report and record findings. Modify the nursing care plan as needed. Counsel the patient regarding abnormal findings; explain the need for possible follow-up testing and treatment. See Interpreting Results of Immunologic Tests.

  2. Follow guidelines in Chapter 1 for safe, effective, informed posttest care.

Interfering Factors ⬆

  1. Antibodies to fungi may be found in blood samples from apparently healthy people.

  2. When testing for blastomycosis, cross-reactions with histoplasmosis may occur.

  3. More than 50% of patients having active blastomycosis yield a negative result by CF.

  4. Recent histoplasmosis skin tests must be avoided because they cause elevated CF test results, which may be due to the stimulation from the skin test and not the systemic infection.