INTENDED USE

The Chagas Ab Rapid Test kit is a lateral flow chromatographic immunoassay for the qualitative detection of IgG anti-Trypanosoma cruzi (T. cruzi) in human serum, plasma or whole blood. It is intended to be used as a screening test and as an aid in the diagnosis of infection with T. cruzi. Any reactive specimen with the Chagas Ab Rapid Test must be confirmed with alternative testing method(s) and clinical findings.

SUMMARY AND EXPLANATION THE TEST

Chagas disease is an insect-borne, zoonotic infection by the protozoan T. cruzi, which causes a systemic infection of humans with acute manifestations and long term sequelae. It is estimated that 16-18 million individuals are infected worldwide, and roughly 50,000 people die each year from chronic Chagas disease (World Health Organization). Buffy coat examination and xenodiagnosis used to be the most commonly methods in the diagnosis of acute T. cruzi infection. However, both methods are either time consuming or lack of sensitivity. Recently, serological test becomes the mainstay in the diagnosis of Chagas’s disease. In particularly, recombinant antigen based tests eliminate false-positive reactions which are commonly seen in the native antigen tests. The Chagas Ab Combo Rapid Test is an instant antibody test which detects IgG antibodies the T. cruzi within 15 minutes without any instrument requirements. By utilizing T. cruzi specific recombinant antigen, the test is highly sensitive and specific.

PRINCIPLE

The Chagas Ab Rapid Test is a lateral flow chromatographic immunoassay based on the principle of indirect immunoassay. The test cassette consists of: 1) a burgundy colored conjugate pad containing Protein A conjugated with colloid gold (Protein A conjugates), 2) a nitrocellulose membrane strip containing a test band (T band) and a control band (C band). The T band is pre-coated with recombinant T. cruzi antigens, and the C band is pre-coated with anti-Protein A antibodies.

When an adequate volume of test specimen is dispensed into the sample well of the test cassette, the specimen migrates by capillary action across the cassette. The IgG antibodies to T. cruzi if present in the specimen will bind to the Protein A conjugates. The immunocomplex is then captured on the membrane by the pre-coated T. cruzi antigens, forming a burgundy colored T band, indicating a Chagas Ab positive test result.
Absence of the T band suggests a negative result. The test contains an internal control (C band) which should exhibit a burgundy colored band of the immunocomplex of anti-protein A antibody-Protein A gold conjugates regardless of color development on the T band. Otherwise, the test result is invalid and the specimen must be retested with another device.