Topic Overview

What is toxoplasmosis?

Toxoplasmosis is infection with the parasite Toxoplasma gondii. In the United States, more than 60 million people probably are infected with the parasite, but very few have symptoms because the immune system is usually able to fight the disease.¹

Toxoplasmosis is dangerous to a pregnant woman and her fetus. For more information, see the topic Toxoplasmosis During Pregnancy.

What causes toxoplasmosis?

Toxoplasmosis can result from:

• Accidentally swallowing Toxoplasma gondii eggs from soil or other contaminated surfaces. This can happen by putting your hands to your mouth after gardening, cleaning a cat’s litter box, or touching anything that has come into contact with cat feces.
• Eating raw or partly cooked meat, especially pork, lamb, or venison, or touching your hands to your mouth after touching the meat.

If you are pregnant when first infected with Toxoplasma gondii, you can give the infection to your baby.

You may also receive it through an organ transplantation or a transfusion, although this is rare.

What are the symptoms?

Most people with toxoplasmosis don't have symptoms. When symptoms are present, they are often flu-like and may include swollen lymph glands or muscle aches and pains that last for a few days to several weeks.

Severe toxoplasmosis results in damage to the eye or the brain. Infants who became infected before birth may be born with serious mental or physical problems.

A person with an immune system weakened by HIV infection, organ transplant medicines, or lymphoma can develop life-threatening toxoplasmosis.

Severe symptoms vary depending on which part of the body is affected. If the infection is in the:

• Brain (encephalitis), symptoms include seizures, sensory changes, weakness, changes in behavior or mental state, and problems with movement.
• Eye (chorioretinitis), symptoms include eye pain and gradual vision loss in one or both eyes.
• Lungs (pneumonia), symptoms include fever and chills, breathing problems and a cough that can cause chest wall pain, fatigue, and weakness.
• Heart (myocarditis), symptoms include irregular heartbeat, signs of pericarditis, and signs of heart failure.

How is toxoplasmosis diagnosed?

Because there are typically no symptoms, it is hard to know whether you are infected. If you think that you may have toxoplasmosis, talk to your doctor. He or she may do specific blood tests for toxoplasmosis.

• If you have an impaired immune system, get the blood test for Toxoplasma gondii. If your test is positive, it means that you have been infected at some time in your life. Your doctor can tell you if and when you need to take medicine to prevent the infection from reactivating. If your test is negative, you have not been infected, and you can take precautions to avoid infection.
• If you are planning to become pregnant, consider being tested for Toxoplasma gondii. If the test is positive, it means you have already been infected at some time in your life and you probably don't have to worry about passing the infection to your future baby (discuss this with your doctor). If the test is negative, take precautions to avoid infection.
• If you are pregnant, you and your doctor should discuss your risk of toxoplasmosis. Your doctor may order a blood sample for testing.