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What is congenital toxoplasmosis?

Toxoplasmosis is a disease caused by the parasite toxoplasma gondii.

  • If the parasite infects a pregnant woman, it can enter the placenta and affect the baby inside.
  • The parasite usually enters the body through the mouth. It can be spread in two ways: eating uncooked or undercooked meat or eggs containing the organism, or by oral contact with either soil or cat feces containing parasite eggs (e.g., gardening in infected soil or handling cat litter or feces and then putting your hands in your mouth).
  • Cats are the only animals that can transmit the toxoplasma gondii parasite directly to people (and only through their feces), but there is no documented correlation between cat ownership—especially if the cats are kept indoors—and toxoplasmosis.
    • Cats can only become infected with the parasite if they eat prey already containing the parasite, or if they come into contact with infected soil. For this reason, cats kept indoors are highly unlikely to be toxoplasma gondii carriers.
    • Despite the old wives’ tale, it’s not necessary to get rid of your cat if you (or a family member) are pregnant. You should be sure to take proper steps to avoid contact with cat litter and feces

If your baby has been infected with the toxoplasma gondii parasite, treatment should begin right away to ensure that the condition has a minimal effect on her health.

Adult holds tiny hand of newborn baby

Quality care

Our Division of Newborn Medicine specializes in treating babies with a wide range of congenital and acquired conditions. Your baby will be seen by a specially trained team of physicians, nurses, therapists, and other health professionals who routinely diagnose and treat newborns with critical illnesses.

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Symptoms & Causes

What are the symptoms of congenital toxoplasmosis?

Many (up to 90 percent of) babies born with congenital toxoplasmosis experience no immediate symptoms. However, one sign of infection is a premature birth or an abnormally low birth weight. As an infected baby grows, more signs and symptoms can appear. These may include the following:

Toxoplasmosis can also cause some more serious problems, including the following:

  • Retinal damage
  • Hydrocephalus: a buildup of cerebrospinal fluid in the brain
  • Intracranial calcifications these indicate areas of the brain that have been damaged by the parasite, and are often linked to the following conditions:
    • Intellectual disabilities
    • Seizures
    • Motor and developmental delays
    • Hearing loss

What causes congenital toxoplasmosis?

The toxoplasma gondii parasite can enter the body in a number of ways (most commonly, through the mouth). If you’re pregnant, be especially careful to avoid these situations:

  • Consuming raw or undercooked meat
  • Eating raw eggs
  • Handling cat feces and/or cat litter (though this doesn’t mean you can’t have a pet cat — see our FAQ section for more information
  • Exposure to insects (e.g., flies) that have been in contact with cat feces

Diagnosis & Treatments

How do we diagnose congenital toxoplasmosis?

The first step in treating your child is forming an accurate and complete diagnosis. A blood test before or during pregnancy can determine if you have been exposed to the toxoplasma gondii parasite.

  • If you are infected, another type of test can determine whether your baby is infected.
  • In addition, fetal ultrasounds can determine if your baby's organs are damaged.

Currently, physicians in the United States do not routinely screen pregnant women for toxoplasma gondii, so if you suspect you may have been exposed to the parasite, ask your doctor to perform a blood test.

After we complete all necessary tests, Boston Children’s Hospital’s experts meet to review and discuss what they have learned. Then we will meet with you and your family to discuss the results and outline the best treatment options.

How do we treat congenital toxoplasmosis?

If the condition is detected early through a blood test, antiparasitic treatments can eliminate toxoplasmosis before the parasite harms the fetus. Clinicians treat babies born with congenital toxoplasmosis with anti-toxoplasmosis medications, usually for 1 year after birth. 

One of our experts will determine which combination of medications is best suited for your baby. We typically use pyrimethamine or sulfadiazine because studies have shown that babies treated with these medications typically have fewer complications from the infection.

What is the long-term outlook for a congenital toxoplasmosis diagnosis?

If your child is treated early, there should be no serious consequences of toxoplasmosis. However, if treatment is delayed, your child may suffer some serious health problems as a result of the infection. For more information, see the diagnosis and treatments section.

How Boston Children’s Hospital approaches congenital toxoplasmosis

Physicians in the Division of Infectious Diseases care for children and adolescents with a variety of infections, including congenital toxoplasmosis. In addition to treating children, we also are dedicated to researching better ways to diagnose, treat and prevent infectious diseases.

Coping & Support

It's essential to remember that, while hearing that your child is infected with toxoplasmosis can feel very isolating, many children and their families have been down this path before. We've helped them, and we can help you, too.

There are lots of resources available for your family — within Boston Children's, in the outside community and online. These include:

  • Patient education: From the very first visit, our nurses will be on hand to walk you through your child's treatment and help answer any questions you may have. And they'll also reach out to you by phone, continuing the care and support you received while at Boston Children's.
  • Parent to parent: Want to talk with someone whose baby has been treated for toxoplasmosis? We can put you in touch with other families who have been through similar experiences and can share their experience.
  • Faith-based support: If you are in need of spiritual support, we'll help connect you with the Boston Children's Department of Spiritual Care (chaplaincy). Our program includes nearly a dozen clergy representing Episcopal, Jewish, Lutheran, Muslim, Roman Catholic, Unitarian and United Church of Christ traditions who will listen to you, pray with you and help you observe your own faith practices during the time you and your child are in the hospital.
  • Social work and mental health professionals: Our social workers and mental health clinicians have helped many other families in your situation. We can offer counseling and assistance with issues such as coping with your child's diagnosis, stresses relating to coping with illness and dealing with financial difficulties.

On our patient resources site, you can read all you need to know about:

Frequently Asked Questions

Toxoplasmosis is a disease caused by the parasite toxoplasma gondii and is usually acquired by the parasite getting into the body by the mouth (for instance, by eating undercooked meat).

While most people infected with toxoplasmosis have no symptoms (and don’t need any treatment), pregnant women should be especially careful about exposing themselves to the parasite because toxoplasmosis can be very serious in a newborn baby.

If you’re pregnant, be especially careful to avoid these situations:

  • Consuming raw or undercooked meat
  • Consuming raw eggs
  • Gardening or doing other yard work that puts you in direct contact with soil
  • Exposure to cat feces and cat litter
  • Exposure to insects (e.g., flies) that have been in contact with cat feces

No. Although cats can transmit the toxoplasma gondii parasite to pregnant women through their feces (where infected parasite eggs can be shed), there is no demonstrated link between toxoplasmosis and simply owning a cat. Here’s why:

Cats themselves can only become infected with toxoplasma gondiiif they eat prey containing the parasite, or come into contact with infected soil. For these reasons, cats kept indoors are highly unlikely to become carriers of the parasite. In addition, only pregnant women are at elevated risk of toxoplasmosis through handling cat litter and/or feces. Other family members, including young children, do not face this elevated risk.

Many pregnant women (and their families) fear that they need to part with the family cat to be safe from toxoplasmosis — but that’s not the case at all. You can keep your cat while taking these steps to prevent toxoplasmosis infection:

  • Keep cats indoors. A cat that doesn’t go outside can’t eat infected prey or come into contact with infected soil.
  • Don’t come into direct contact with cat litter or feces. Have another family member take care of cleaning the litter box and disposing of cat waste. If you must handle litter box duties yourself, always wear disposable gloves and be sure to wash your hands thoroughly afterward.

It depends on when you are infected.

  • The risk of maternal transmission of the parasite to the fetus during the first trimester of pregnancy (when the baby is most vulnerable) is relatively low, at 15 to 20 percent.
  • However, by the third trimester, a pregnant woman with toxoplasmosis has a 60 percent chance of infecting her child.

A blood test before or during pregnancy can determine if you have been exposed to the toxoplasma gondii parasite.

  • If you are infected, another type of test can determine whether your baby is infected.
  • In addition, fetal ultrasounds can determine if your baby's organs are damaged.

Currently, physicians in the United States do not routinely screen pregnant women for toxoplasma gondii, so if you suspect you may have been exposed to the parasite, ask your doctor to perform a blood test.

Many babies show no immediate signs of infection. However, as a baby grows, she may show more signs of infection, which may include the following:

Here at Boston Children’s, physicians in our Division of Infectious Diseases treat congenital toxoplasmosis in infants.

  • If detected early through a blood test, antiparasitic treatments can eliminate toxoplasmosis before the parasite harms the fetus.
  • We treat babies born with congenital toxoplasmosis with anti-toxoplasmosis medications, usually for 1 year after birth.
  • One of our experts will determine which combination of medications is best suited for your baby.

If your child is treated early, there should be no serious consequences of toxoplasmosis. However, if treatment is delayed, your child may suffer some serious health problems as a result of the infection.

Our physicians are expert, compassionate and committed to focusing on the whole child, not just his condition — that’s one reason we’re frequently ranked as a top pediatric hospital in the United States.

And at Boston Children’s, we consider you and your child integral parts of the care team and not simply recipients of care. You and your care team will work together to customize a plan of care for your child.