ToRCH Overview
ToRCH is an acronym for a group of infections that can cause significant birth defects and even fetal death. Meridian Life Science offers a complete range of antigens and other reagents for the detection of IgG and IgM antibodies in various assay formats such as EIA, rapid anti-IgM assays and Immunofluorescence (IFA).
IgM vs IgG SEROLOGY TIMELINE
The ToRCH test measures the levels of an infant’s antibodies against five groups of chronic infections: toxoplasmosis, rubella, cytomegalovirus (CMV), herpes simplex virus (HSV) and other infections. The “other infections” usually include syphilis, hepatitis B, coxsackie virus, Epstein-Barr virus (EBV), varicella-zoster virus (VZV), and human parvovirus. These infectious diseases are all associated with congenital abnormalities resulting from maternal infection. Although these organisms typically cause only asymptomatic or mild infection in the mother, they can have serious consequences for the fetus. If the infection occurs during the first three months of pregnancy and if it is a primary infection (newly acquired during pregnancy), the risk of congenital abnormalities is much higher as compared to a secondary or reactivated infection. CMV is the most common cause of congenital infectious disease with a much higher rate of transmission (10% vs. 1%) for mothers with a primary infection compared to a reactivation. Consequently it is a very important part of prenatal care to recognize these infections in the first trimester of pregnancy.
For most ToRCH organisms, the initial screening test is based on the detection of antibodies to the organism. Subsequent screening, if required, is carried out using a monoclonal antibody-based immunofluorescent assay (IFA). Assays are commercially available for the detection of IgG, IgM, or both IgG/IgM antibodies. In most cases, IgG reactivity in the absence of IgM reactivity is indicative of a past infection, while IgM reactivity in the absence of IgG reactivity indicates a current infection. However, for some ToRCH diseases such as toxoplasmosis and CMV infections, IgG avidity has recently been found to be useful for identifying primary infections. An IgG antibody produced in the first few months following an initial infection has a lower avidity than an IgG antibody produced several months or years later; consequently, low-avidity antibody can be used to specifically identify high-risk mothers with a primary infection. To protect a fetus from ToRCH infection, early diagnosis through first trimester screening is critical.
2 | ToRCH REAGENTS - IgG and IgM Assay Development
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