CausesBy Mayo Clinic staff
Toxoplasma gondii (T. gondii) is a single-celled parasitic organism that can infect most animals and birds. But because it reproduces sexually only in cats, wild and domestic felines are the parasite's ultimate host.
When a person becomes infected with T. gondii, the parasite forms cysts that can affect almost any part of the body — often your brain and muscles, including the heart.
If you're generally healthy, your immune system keeps the parasites in check. They remain in your body in an inactive state, providing you with lifelong immunity so that you can't become infected with the parasite again. But if your resistance is weakened by disease or certain medications, the infection can be reactivated, leading to serious complications.
Although you can't "catch" toxoplasmosis from an infected child or adult, you can become infected if you:
- Come into contact with cat feces that contain the parasite. You may accidentally ingest the parasites if you touch your mouth after gardening, cleaning a litter box or touching anything that has come in contact with infected cat feces. Cats who hunt or who are fed raw meat are most likely to harbor T. gondii.
- Eat contaminated food or drink contaminated water. Lamb, pork and venison are especially likely to be infected with T. gondii. Occasionally, unpasteurized dairy products also may contain the parasite. Water can be contaminated with T. gondii, too, but this isn't common in the United States.
- Use contaminated knives, cutting boards or other utensils. Kitchen utensils that come in contact with raw meat can harbor the parasites unless the utensils are washed thoroughly in plenty of hot, soapy water.
- Eat unwashed fruits and vegetables. The surface of fruits and vegetables may contain traces of the parasite. To be safe, thoroughly wash all produce, especially any you eat raw.
- Receive an infected organ transplant or transfused blood. In rare cases, toxoplasmosis can be transmitted through an organ transplant or blood transfusion.
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