Toxoplasmosis is an infection caused by the parasite Toxoplasma gondii. T. gondii is a microscopic parasite that infects cats and can be found in the soil. Testing 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. Testing is performed in order to detect and diagnose a current or past infection. In most healthy people, toxoplasmosis either causes no symptoms or results in a mild flu-like illness. A person’s immune system keeps the infection dormant and protects the body against further infection, unless the immune system becomes weakened, in which case the infection can re-activate. Sample: Blood (serum) Reference: For IgG, less than 3.0 IU/ml; for IgM, less than 1.0 IU/ml Frequency: Twice a week