What is included in the serologic diagnosis of Chagas disease (American trypanosomiasis)?

Updated: Apr 26, 2019
  • Author: Louis V Kirchhoff, MD, MPH; Chief Editor: Pranatharthi Haran Chandrasekar, MBBS, MD  more...
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Answer

Tests for anti– T cruzi immunoglobulin M (IgM) are not standardized, are not available commercially, and should play no role in the diagnosis of acute Chagas disease.

Serologic testing for specific antibodies to T cruzi is the cornerstone of diagnosing chronic T cruzi infection.

Several dozen serologic assays are available in the endemic countries for testing clinical and donor specimens for chronic T cruzi infection. Several of these are available in nonendemic areas with substantial at‑risk immigrant populations. The most widely used today are indirect immunofluorescence (IIF), enzyme-linked immunosorbent assay (ELISA), and indirect hemagglutination, but assays based on other formats are also available. Most use lysates of epimastigotes as target antigens, but several are based on recombinant proteins. [91] At least a dozen rapid tests for diagnosing chronic T cruzi infection have also made it to market. [128]

To ensure accurate results, WHO Chagas experts and other authorities recommend that each specimen undergo testing with two types of assays, and this approach is generally followed for blood donor testing in endemic countries, although in Brazil a single‑assay testing protocol is used to screen donors.

In the United States, the Ortho T cruzi ELISA Test System and the Abbott Prism Chagas Assay are both FDA‑approved for donor screening, but not for clinical testing.

From 2007 through 2014, the Chagas Radioimmune Precipitation Assay (Chagas RIPA) was performed by Quest Diagnostics for confirmatory testing of donor specimens that were repeat positive in the Ortho or Abbott screening assays. [90, 91] Currently, the Abbott Enzyme Strip Assay Chagas (ESA Chagas) is the only FDA‑approved assay for confirmatory testing available in the United States. The Chagas RIPA is available for research and limited clinical testing in the author’s laboratory at the University of Iowa.

Currently, two ELISAs are approved by the FDA for clinical testing (Hemagen Chagas Kit, Hemagen Diagnostics, Inc.; Chagatest ELISA Recombinante v. 3.0, Laboratorios Wiener). For initial testing, the author suggests using the latter through the Division of Parasitic Diseases of the Centers for Disease Control and Prevention (CDC). In all instances, positive and indeterminate results should be confirmed with the Chagas RIPA or the Abbott ESA Chagas. 


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