Toxoplasmosis is an infection caused by a tiny organism called a protozoon. Many people are infected with this protozoon. However, few people have any symptoms or problems from it.

Toxoplasmosis is passed from animals to humans. People can contract it by:

  • Touching infected cat feces or something that has had contact with cat feces, such as soil or insects
  • Eating undercooked, infected meat, or by touching your mouth after touching the meat
  • In rare cases, receiving a blood transfusion or an organ transplant

A pregnant woman who gets toxoplasmosis for the first time may pass it to her unborn child. Active infection usually occurs one time in a person’s life, although the protozoon remains inactive in the body. Generally, if a woman has become immune to the infection before getting pregnant, she will not pass the condition to her baby.