Test Details: Toxoplasmosis is an infection caused by the parasite Toxoplasma gondii. Diagnosis can be made by serologic testing or by molecular testing. Serologic testing detects antibodies in the blood that are produced in response to an infection and depending on the type of antibodies present (IgG or IgM), a current or past infection can be determined. IgM antibodies are the first to be produced by the body in response to a Toxoplasma infection. They are present in most individuals within a week or two after the initial exposure. IgM antibody production rises for a short time period and declines. Eventually, sometimes months after the initial infection, the level (titer) of IgM antibody falls below a detectable level in most people. Additional IgM may be produced when dormant T. gondii is reactivated and/or when a person has a chronic infection.