INTENDED USE

The Toxo IgG/IgM Rapid Test is a lateral flow immunoassay for the simultaneous detection and differentiation of IgM and IgG antibodies to Toxoplasma gondii (T. gondii)
in human serum, plasma or whole blood. It is intended to be used by professionals as a screening test and provides a preliminary test result to aid in the diagnosis of
infection with T. gondii.

SUMMARY

T. gondii is an obligate intracellular protozoan parasite with a worldwide distribution. Serological data indicates that approximately 6-47% of the population is chronically infected with the organism. A T. gondii infection occurs essentially without knowledge of the patient and may be unrelated to direct exposure to a cat (e.g., by ingestion of vegetables or water contaminated with oocysts or ingestion of undercooked meat contaminated with cysts). An initial T. gondii infection and the subsequent chronic infection are clinically undetected in 80% to 89% of healthy individual. In immunosuppressed patients, such as patients infected with HIV, both acute and recurrent toxoplasmosis can have severe clinical manifestations. In pregnant women, an acute T. gondii infection may lead to serious fetal congenital mental retardation, blindness and hydrocephaly.

Methods for diagnosis of toxoplasmosis include PCR, histological diagnosis, parasite isolation and serology. Serological detection of T. gondii specific IgM and IgG antibodies is the primary method for diagnosis of toxoplasmosis. Diagnosis of toxoplasmosis is helpful in determining the risk for congenital toxoplasmosis during pregnancy.
IgM anti-T. gondii develops during acute primary infection with T. gondii and declines generally within a few months. IgG anti-T. gondii develops generally within 1–2 weeks post infection, peaks within 1–2 months, and usually persists for life. The absence of IgG antibodies before or early in pregnancy allows the identification of women at risk of acquiring infection. Additionally, the presence of IgG allows the identification of immunocompromised patients at risk for the reactivation of a latent infection.

The Toxo IgG/IgM Rapid Test detects IgM and IgG anti-T. gondii in human serum, plasma or whole blood by utilizing T. gondii-specific antigens. The test can be performed within 10 minutes by minimally skilled personnel without the use of laboratory equipment.

PRINCIPLES

The Toxo IgG/IgM Combo Rapid Test is a lateral flow chromatographic immunoassay. The test strip in cassette device consists of: 1) a burgundy colored conjugate pad containing a recombinant T. S gondii antigen conjugated with colloidal gold (Toxo conjugates) and a control antibody conjugated with colloidal gold and 2) a nitrocellulose membrane strip containing two test lines (G and M lines) and a control line (C line). The G line is pre-coated with anti-human IgG for detection of IgG anti-T. gondii. The M line is pre-coated with mouse anti-human IgM for detection of IgM anti-T. gondii. The C line is pre-coated with a control antibody.

When an adequate volume of test specimen and sample diluent is dispensed into the sample well and buffer well, respectively, the specimen migrates by capillary action across the test strip. IgM anti-T. gondii, if present in the specimen, will bind to the Toxo conjugates. The immunocomplex is then captured on the membrane by the pre-coated anti-human IgM forming a burgundy colored M line, indicating an IgM anti-T. gondii positive test result. IgG anti-T. gondii, if present in the specimen, will bind to the Toxo conjugates. The immunocomplex is then captured on the membrane by the pre-coated anti-human IgG forming a burgundy colored G line, indicating an IgG anti-T. gondii positive test result.

Absence of any test lines (G or M) suggests a negative test result. The test contains an internal control (C line) which should exhibit a burgundy colored line of the immunocomplex of the control antibodies, regardless of color development on the test lines (G and M). If no control line (C line) develops, the test result is invalid and the specimen must be retested with another device.