Diagnosis of chronic Trypanosoma cruzi infection (Chagas disease)
Only orderable as part of a profile. For more information see CRUZI / Trypanosoma cruzi (Chagas) Antibody Panel, Serum.
Lateral Flow Assay (LFA)
American trypanosomiasis
Chagas
Chagas disease
Kissing bug
Reduviid
T cruzi
Triatoma
Trypanosoma
Trypanosomiasis
CHAGL
CRUZI
Serum
Only orderable as part of a profile. For more information see CRUZI / Trypanosoma cruzi (Chagas) Antibody Panel, Serum.
Supplies: Sarstedt Aliquot Tube 5 mL (T914)
Collection Container/Tube:
Preferred: Serum gel
Acceptable: Red top
Submission Container/Tube: Plastic vial
Specimen Volume: 0.2 mL
Collection Instructions: Centrifuge and aliquot serum into a plastic vial.
0.10 mL
Gross hemolysis | Reject |
Gross lipemia | Reject |
Specimen Type | Temperature | Time | Special Container |
---|---|---|---|
Serum | Frozen | 14 days |
Diagnosis of chronic Trypanosoma cruzi infection (Chagas disease)
Chagas disease (American trypanosomiasis) is caused by the protozoan hemoflagellate Trypanosoma cruzi and can lead to acute and chronic clinical manifestations of disease. T cruzi is endemic in many areas of South and Central America. The parasite is usually transmitted by the bite of reduviid (or "kissing") bugs of the genus Triatoma but may also be transmitted by blood transfusion, organ transplantation, food ingestion, and vertically from mother to fetus. The acute febrile stage of disease is frequently undiagnosed and often resolves spontaneously. Diagnosis of acute T cruzi infection is typically confirmed by microscopic identification of trypomastigotes in fresh preparations of anticoagulated blood or buffy coat or by molecular detection. Parasitemia decreases and is undetectable within approximately 90 days of infection.
Chronic T cruzi infections are often asymptomatic but may progress to produce disabling and life-threatening cardiac (cardiomegaly, conduction defects) and gastrointestinal (megaesophagus and megacolon) disease. These damaged tissues contain the intracellular amastigote of T cruzi. The parasite is not seen in the blood during the chronic phase. Diagnosis of chronic T cruzi infection relies on serologic detection of antibodies to this organism. However, no single serologic assay is sensitive and specific enough to be relied upon alone. Therefore, per current expert guidelines and the Centers of Disease Control and Prevention, serologic confirmation of chronic T cruzi infection requires positivity on 2 tests utilizing two different methodologies and/or two different T cruzi antigen preparations. When results are discordant, testing by a third assay is recommended to resolve the initial results or, alternatively, repeat testing on a new sample may be required.
Only orderable as part of a profile. For more information see CRUZI / Trypanosoma cruzi (Chagas) Antibody Panel, Serum.
Negative
Reference values apply to all ages.
CHAGS result | CHAGL result | Interpretive comment |
Positive | Positive | Antibodies to Trypanosoma cruzi (Chagas disease) detected by two separate methods, suggesting current or past infection. Results should be interpreted alongside clinical presentation and exposure history. |
Positive | Negative | Antibodies to Trypanosoma cruzi (Chagas disease) detected by one of two assays. Discordant results can be resolved through submission of a new sample for testing or through additional testing at a public health laboratory. |
Positive | Invalid | Submission of a new sample is recommended to resolve discordant results. |
Indeterminate | Positive | Antibodies to Trypanosoma cruzi (Chagas disease) detected by one of two assays. Discordant results can be resolved through submission of a new sample for testing or through additional testing at a public health laboratory. |
Indeterminate | Negative | Submission of a new sample is recommended to resolve discordant results. |
Indeterminate | Invalid | Submission of a new sample is recommended to resolve discordant results. |
Negative | Positive | Antibodies to Trypanosoma cruzi (Chagas disease) detected by one of two assays. Discordant results can be resolved through submission of a new sample for testing or through additional testing at a public health laboratory. |
Negative | Negative | No antibodies to Trypanosoma cruzi (Chagas disease) detected. False negative results may occur in patients tested within 4 weeks of infection. |
Negative | Invalid | Submission of a new sample is recommended to resolve discordant results. |
False-positive results may occur in patients infected with Leishmania species or other Trypanosoma species, including Trypanosoma rangeli. Additionally, false-positive results with the T cruzi lateral flow assay have been detected in patients with hepatitis C, toxoplasmosis, or syphilis.
A diagnosis of chronic Chagas disease requires both clinical evaluation (including exposure history) and laboratory results. Chagas disease should not be diagnosed based on a single serologic result alone.
A single negative result does not exclude the diagnosis of Chagas disease as antibodies to the pathogen may not yet be detectable. Sensitivity of the assay may be decreased in significantly immunosuppressed patients.
1. Bern C, Montgomery SP, Herwaldt BL, et al. Evaluation and treatment of Chagas disease in the United States: a systematic review JAMA. 2007;298(18):2171-2181
2. Bern C, Messenger LA, Whitman JD, Maguire JH. Chagas disease in the United States: A public health approach. Clin Microbiol Rev. 2019;33(1):e00023-19. doi:10.1128/CMR.00023-19
3. Forsyth CJ, Manne-Goehler J, Bern C, et al. Recommendations for screening and diagnosis of Chagas disease in the United States. J Infect Dis. 2022;225(9):1601-1610. doi:10.1093/infdis/jiab513
The Chagas DetectTM Plus Rapid Test is a qualitative, membrane-based immunoassay for the detection of antibodies to Trypanosoma cruzi in human serum and whole blood matrices (venous and capillary [finger prick] whole blood). The rapid test membrane is precoated with a recombinant antigen on the test line region and utilizes a separate control to assure assay flow and performance. During testing, the sample and a proprietary blend of a stable liquid conjugate labeled with protein A are added to the sample pad. The conjugate and serum mixture migrates upward on the membrane (via capillary action) to react with recombinant T cruzi antigen on the membrane. If antibodies to the T cruzi antigen are present, a red line will appear at the test line. The red line at the control region should always appear if the assay is performed correctly. The presence of this red line verifies that proper flow has occurred and catastrophic failure of the conjugate has not occurred.(Package insert: Chagas Detect Plus Rapid Test. InBios; 01/05/2018)
Monday
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.
86753
Test Id | Test Order Name | Order LOINC Value |
---|---|---|
CHAGL | T. cruzi IgG, LFA, S | 87994-0 |
Result Id | Test Result Name |
Result LOINC Value
Applies only to results expressed in units of measure originally reported by the performing laboratory. These values do not apply to results that are converted to other units of measure.
|
---|---|---|
CHAGL | T. cruzi IgG, LFA, S | 87994-0 |