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• Immunofluorescence Assay (IFA)

  This test is best suited for low-volume testing
• Positive IFA result

  Titer of 1:256 or higher is obtained
• Other closely related organisms

  May cross-react and cause biological false positive results in IFA for Lyme disease
• Autoimmune connective tissue diseases

  Can also produce false positives in the IFA assay for Lyme disease and the FTA assay for syphilis
• Enzyme Immunoassay (EIA)

  Quick, reproducible (not subjective), relatively inexpensive, and lends itself well to automation and high-volume testing
• False positives in EIA

  Occur with syphilis and other treponemal diseases, relapsing fever, leptospirosis, infectious mononucleosis, Rocky Mountain spotted fever, and autoimmune diseases
• Western Blot

  Used as a confirmatory test for samples that initially test positive or equivocal by EIA or IFA
• IgM immunoblot positive

  Two of the following bands must be present: 23(Osp C), 39, and 41 (flagellin) kDa
• IgG immunoblot positive

  Any 5 of the 10 bands (18, 23, 28, 30, 39, 41, 45, 58, 66, and 93 kDa) are positive
• The detection and diagnosis of fungal and parasitic infections relies on laboratory methods as well as the patient's clinical symptoms, medical history, geographic location, and travel history
• Traditional "gold standard" for fungal infections

  Recovery of the organism in the laboratory
• Potential outcomes of host and parasite interactions

  • Natural resistance
  • Symbiosis
  • Commensalism
  • Sterilizing immunity
  • Concomitant immunity
  • Ineffective immunity
• Th1 cells have been shown in mice to be vitally important to clearance of the organism in cryptococcosis and histoplasmosis
• Rapid Antigen Detection Systems (RDTS)

  Based on immunochromatographic antigen detection, widely used in diagnostic laboratories
• Diagnosis of aspergillosis

  Requires a positive tissue biopsy demonstrating the hyphae or a positive culture for Aspergillus
• Detection of galactomannan in serum by EIA

  Has increased the ability to diagnose invasive aspergillosis
• Detection of β-D-glucan (BDG) in serum

  Another assay to detect invasive fungal infections, including aspergillosis
• Cryptococcus neoformans capsule

  Consists of polysaccharide containing an unbranched chain of alpha-1,3-linked mannose units substituted with xylosyl and β-glucuronyl groups
• Tube Agglutination (TA) test for Cryptococcus neoformans

  Can be used as both a qualitative screening test and a semiquantitative test to detect antibodies to C. neoformans
• India Ink test

  Serological test that detects the polysaccharide capsule antigen in serum and CSF of patients with suspected infection with Cryptococcus neoformans
• Cryptococcal Latex Agglutination test

  Detection of cryptococcal polysaccharide antigen in serum and CSF
• Cross-reactions in Cryptococcal Latex Agglutination test

  May occur due to rheumatoid factor (RF) or circulating antibodies that bind with nonreactive polysaccharide in immune complexes, causing false positive results
• Remedy of cross-reactivity in Cryptococcal Latex Agglutination test

  False-positive results in spinal fluid can be eliminated by heating the specimen in a boiling water bath for 5 minutes
• Indirect Immunofluorescence Assay for Cryptococcosis

  Most valuable when antigen tests are negative; can be combined with antigen tests to determine the patient's prognosis
• Diagnosis of Candida infections

  Generally involves the recovery of the causative agent
• Direct examination of clinical material using 10% potassium hydroxide (KOH)

  May also be used to detect Candida species
• Detection of mannan and anti-mannan antibodies in serum

  Current recommendations for the specific identification of Candida species
• Peptide Nuclear Acid Fluorescent In Situ Hybridization (PNA-FISH)

  Technique used to differentiate Candida albicans from other Candida species
• Complement Fixation test for Coccidioidomycosis (IgG test)

  The most widely used quantitative serodiagnostic method for identifying C. immitis infections
• False-negative results in Complement Fixation test for Coccidioidomycosis

  Occur in patients with solitary pulmonary lesions
• Cross-reactions in Complement Fixation test for Coccidioidomycosis

  Occur in patients with acute histoplasmosis, causing false-positive reactions
• Tube Precipitation test for Coccidioidomycosis (IgM test)

  Precipitating IgM antibodies appear in 1 to 3 weeks after infection in 90 percent of symptomatic patients
• ELISA for Coccidioidomycosis

  Tests for IgG and IgM antibodies, positive results should be confirmed with Complement Fixation or Tube Precipitation tests
• Complement Fixation and Precipitation tests for Histoplasmosis

  Most common tests used for detection of Histoplasma antibodies
• Precipitin band testing for Histoplasmosis

  Looks for the presence of H and M antibodies in the serum, H antibodies signify active infection, M antibodies indicate exposure
• ELISA for Histoplasmosis

  Used to detect the polysaccharide antigen in serum or urine, urinary antigen tests have high sensitivity and specificity
• SREHP (Serine Rich E. histolytica Protein)

  Used for the identification of E. histolytica
• Sabin-Feldman Dye test for Toxoplasmosis

  Considered the gold standard test, can detect IgG antibodies
• Labeled Immunoassays for Toxoplasmosis

  ELISA, IFA, and Chemiluminescence immunoassay for the detection of IgM and/or IgG antibodies
• IgM antibodies for Toxoplasmosis

  May persist for up to 18 months after infection, so sole results of a single assay should not be used to determine a recent infection