Toxoplasmosis affects birds and mammals worldwide. The
incidence of human toxoplasmosis in any given area is influenced by diet and
hygiene practices. For example, in areas where raw or rare meat is commonly
eaten, as in France, toxoplasmosis can affect more than half of the
population.1 Eating infected meat is thought to cause
about half of toxoplasmosis cases in the United States.2
Although nationwide toxoplasmosis statistics are not available,
various studies reflect that infection with and immunity to Toxoplasma gondii varies widely across the United
States.2 For example, while a Denver study has
reported a 3% rate of preexisting immunity among pregnant women, a 30% rate has
been observed in Birmingham, Alabama.1
Because American women are not routinely screened for toxoplasmosis
during pregnancy, it is impossible to know how many pregnant women actually
become infected. In the U.S., 1 to 10 newborns are infected in 10,000
births.3 This number is a fraction of the population
of women who become infected during pregnancy. This is because many fetuses do
not become infected along with their mothers.1