Canis ISSN: 2398-2942

Toxoplasma antibody titer

Contributor(s): Kathleen P Freeman, Kerry Simpson

Overview

  • Enzyme-linked immunosorbent assay now most commonly used, available for IgG, IgM, antigen and immune complexes.
  • Other tests: indirect immunofluorescence, indirect hemagglutination, latex agglutination, polymerase chain reaction (PCR).
  • Single positive titer only indicates exposure, not recent or active infection (may persist for years).

Sampling

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Tests

Methodologies

  • Several:

ELISA - IgG

  • Titer rises 10-15 days post infection, may persist for years.
  • False positives in auto-immune diseases.

ELISA - IgM

  • Titer rises 7-10 days post-infection: often become negative after several months.

PCR

  • Detects Toxoplasma DNA.
  • Detection of parasite in tissue relies on the presence of a tissue cyst in the aliquot.
  • Can be used on tissues, CSF, vitreous/aqueous humor, bronchoalveolar lavage, pleural, or peritoneal effusions.

Indirect hemagglutination

  • Titer rises 22-30 days post-infection.
  • Detects IgG to cytoplasmic antigen.

Indirect immunofluorescence

  • Titer rises 10-15 days post-infection.
  • Measures attachment of antibody to Toxoplasma tachyzoites affixed to a slide.

Latex agglutination

  • Titer rises 14-21 days post-infection.
  • Detects IgG and IgM.
  • False positives with rheumatoid factor Rheumatoid factor.

Validity

Sensitivity

Specificity

  • Depends on test, eg possible false positives in auto-immune disease.
  • Immunofluorescent assays Immunofluorescent antigen tests more likely to give false negative results than ELISA.

Technique (intrinsic) limitations

  • Definitive diagnosis of active infection.
  • Antibody titers in chronic disease may be similar to normal animals.

Technician (extrinsic) limitations

  • Depends on test.

Result Data

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Further Reading

Publications

Refereed papers

  • Recent references from VetMed Resource and PubMed.
  • Bresciani K D, Costa A J, Toniollo G H, Sabatini G A, Moraes F R, Paulillo A C & Ferraudo A S (1999) Experimental toxoplasmosis in pregnant bitches. Vet Parasitol 86(2), 143-145.
  • Tomas W B (1998) Inflammatory diseases of the central nervous system in dogs. Clin Tech Small Anim Pract 13(3), 167-168.
  • Stiles J, Prade R & Greene C (1996) Detection of Toxoplasma gondii in feline and canine biological samples by use of the polymerase chain reaction. Am J Vet Res 57(3), 264-267.
  • Wilson M et al(1990) Serologic aspects of toxoplasmosis. JAVMA 196, 277.


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