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HelpTest ID TXMGP Toxoplasma gondii Antibody, IgM and IgG, Serum
Specimen Required
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Aliquot tube
Specimen Volume: 1.5 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
Forms
If not ordering electronically, complete, print, and send Infectious Disease Serology Test Request (T916) with the specimen.
Secondary ID
39857Useful For
Determining whether a patient has had previous exposure to or recent infection with Toxoplasma gondii
IgG is not useful for diagnosing infection in infants younger than 6 months of age. IgG antibodies in this age group usually are the result of passive transfer from the mother.
Profile Information
| Test ID | Reporting Name | Available Separately | Always Performed |
|---|---|---|---|
| TXM | Toxoplasma Ab, IgM, S | Yes | Yes |
| TOXGP | Toxoplasma Ab, IgG, S | Yes | Yes |
Testing Algorithm
Special Instructions
Method Name
Multiplex Flow Immunoassay (MFI)
Reporting Name
Toxoplasma Ab, IgM and IgG, SSpecimen Type
SerumSpecimen Minimum Volume
0.8 mL
Specimen Stability Information
| Specimen Type | Temperature | Time |
|---|---|---|
| Serum | Refrigerated (preferred) | 14 days |
| Frozen | 14 days |
Clinical Information
Toxoplasma gondii is an obligate intracellular protozoan parasite capable of infecting a variety of intermediate hosts, including humans. Infected definitive hosts (cats) shed oocysts in feces that rapidly mature in the soil and become infectious.(1) Toxoplasmosis is acquired by humans through ingestion of food or water contaminated with cat feces or through eating undercooked meat containing viable oocysts. Vertical transmission of the parasite through the placenta can also occur, leading to congenital toxoplasmosis. Following primary infection, T gondii can remain latent for the life of the host; the risk for reactivation is highest among individuals who are immunosuppressed.
Seroprevalence studies performed in the United States indicate approximately 6.7% of individuals between the ages of 12 and 49 have antibodies to T gondii.(2)
Infection of immunocompetent adults is typically asymptomatic. In symptomatic cases, patients most frequently present with lymphadenopathy and other nonspecific constitutional symptoms, making definitive diagnosis difficult to determine.
Severe-to-fatal infections can occur among patients with AIDS or individuals that are otherwise immunosuppressed. These infections are thought to be caused by reactivation of latent infections and commonly involve the central nervous system.(3)
Transplacental transmission of the parasites resulting in congenital toxoplasmosis can occur during the acute phase of acquired maternal infection. The risk of fetal infection is a function of the time at which acute maternal infection occurs during gestation.(4) The incidence of congenital toxoplasmosis increases as pregnancy progresses; conversely, the severity of congenital toxoplasmosis is greatest when maternal infection is acquired early during pregnancy. A majority of infants infected in utero are asymptomatic at birth, particularly if maternal infection occurs during the third trimester, with sequelae appearing later in life. Congenital toxoplasmosis results in severe generalized or neurologic disease in about 20% to 30% of the infants infected in utero; approximately 10% exhibit ocular involvement only, and the remainder are asymptomatic at birth. Subclinical infection may result in premature delivery and subsequent neurologic, intellectual, and audiologic defects.
Reference Values
Toxoplasma IgM
Negative
Toxoplasma IgG
Negative
Toxoplasma IgG Value
≤9 IU/mL (Negative)
10-11 IU/mL (Equivocal)
≥12 IU/mL (Positive)
Reference values apply to all ages.
Cautions
Diagnosis of recent infection by Toxoplasma gondii can only be established by a combination of clinical and serological data.
The result of a single serum specimen does not constitute sufficient proof for diagnosis of recent infection. If a serum specimen was collected too soon after infection, IgM antibodies to T gondii may be absent. If this is suspected, a second serum specimen should be collected 2 to 3 weeks later and the test repeated.
Sera collected very early during the acute stage of infection may have Toxoplasma IgG levels below 9 IU/mL. The Toxoplasma IgG assay should not be used alone to diagnose recent T gondii infection. Results should be considered in conjunction with clinical presentation, patient history, and other laboratory findings.
Results should be interpreted with caution in patients who are either HIV-positive, receiving immunosuppressive therapy, or have other disorders leading to immunosuppression.
Heterophile antibodies in the patient specimens may interfere with the assay performance.
As with any low prevalence analyte, there is the increased possibility that a positive result may actually be false, reducing the assay's positive predictive value. Per the Public Health Advisory (07/25/1997), the US Food and Drug Administration suggests that sera found to be positive for T gondii IgM antibodies should be submitted to a Toxoplasma reference laboratory.
The performance characteristics of this assay have not been evaluated in immunocompromised individuals and have not been established for cord blood or for testing of neonates.
Day(s) Performed
Monday through Saturday
Report Available
Same day/1 to 3 daysPerforming Laboratory
Mayo Clinic Laboratories in Rochester
Test Classification
This test has been cleared, approved, or is exempt by the US Food and Drug Administration and is used per manufacturer's instructions. Performance characteristics were verified by Mayo Clinic in a manner consistent with CLIA requirements.CPT Code Information
86778-Toxoplasma IgM
86777-Toxoplasma IgG