1. If I have a positive antibody test, does that mean I am infected?
A positive IgG antibody test does mean you have been infected either in the past or present with the agent. If the blood sample is drawn close to the onset of illness, a positive IgG probably means your exposure was more than a month ago and may have occurred years prior to this current illness. By comparing the amount of antibody present in two blood samples drawn 2-3 weeks apart, the physician can tell if the IgG levels are increasing (associated with recent infection) or they are stable (associated with past infection). Interpreting a positive IgM antibody test is more difficult since false positive results may occur. Any positive results should be confirmed with additional specific tests before the diagnosis is considered valid. If your doctor suspects that you or your newborn may have one of these infections, even though the results were negative, other tests for the suspected infection should be done.
2. What type of testing is used to confirm infection with these microorganisms?
To make the diagnosis of an active infection with one of the TORCH pathogens, more specific confirmatory tests may be required. In a baby, cerebrospinal fluid testing (requiring a lumbar puncture or "spinal tap") is often used to confirm toxoplasmosis, herpes and rubella; urine may be cultured for cytomegalovirus; and skin lesions may be scraped and cultured for herpes simplex virus. Making the diagnosis of toxoplasmosis in the pregnant woman or the baby may require additional blood samples, which are sent to a reference lab that specializes in this testing.
This article was last reviewed on July 20, 2011. | This article was last modified on June 4, 2014.
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