T. gondii is an obligate intracellular protozoan parasite with a worldwide distribution. Serological data indicates that approximately 30% of the population of most industrialized nations is chronically infected with the organism. Initial contact with the pathogen during pregnancy can result in transmission of the pathogens to the fetus resulting in severe damage. The diagnosis of toxoplasmosis is typically made by serologic testing. IgG detection is used to determine if a person has been previously exposed to the organism. If it is necessary to try to estimate the time of infection, which is of particular importance for pregnant women, a test that detects IgM is used along with other tests such as an avidity test.