The Toxoplasmosis test by Polymerase Chain Reaction (PCR) is used to detect a Toxoplasma gondii infection in a pregnant woman, unborn baby, or in a person with a weak immune system carrying flu-like symptoms. Toxoplasmosis is an infection caused by the parasite Toxoplasma gondii. This test detects antibodies in the blood that are produced in response to an infection or detects the genetic material (DNA) of the parasite in the blood. This test is also used to determine if a person has been previously infected or to help determine if complications are due to an active Toxoplasma infection.