Medically Reviewed by Amita Shroff, MD on November 30, 2022
5 min read

Toxoplasmosis is an infection caused by a parasite called Toxoplasma gondii. You can find it in the intestines of some animals, including cats and pigs.

The infection can cause cysts to form in your body, usually in your brain and muscles, including your heart. But if your immune system is healthy, it isn’t likely to cause you any trouble. You can have toxoplasmosis without knowing it.

It’s more likely to cause problems in people whose immune systems aren’t at full strength because of a health problem like HIV, or some types of cancer or cancer treatments. It also can be harmful to babies as they develop in the womb -- a pregnant woman can pass it to their baby. It can cause issues with the brain or eyes.

Toxoplasmosis symptoms in babies

Babies may get toxoplasmosis if the mother has been infected just before or during the pregnancy, even if they don’t have signs of the disease. Many early infections end in stillbirth or miscarriage. If the baby survives, they may have serious problems like:

  • Seizures
  • Enlarged liver or spleen
  • Jaundice (yellowing of skin and eyes)
  • Serious eye infections

Often, babies with toxoplasmosis don’t show any signs of it at birth. The symptoms (like hearing loss, mental disability, or severe eye infections) show up in the teen years.

Toxoplasmosis symptoms in older children and adults

Symptoms of toxoplasmosis can feel a lot like the flu. They include:

  • Headaches
  • Body aches
  • Fever
  • Feeling more tired than usual

If your immune system isn’t working like it should because of another health problem, you also may have more serious symptoms, such as:

You might come into contact with the parasite if you:

  • Clean out a cat’s litter box or touch anything that has touched infected cat feces
  • Touch your mouth after gardening and accidently ingest parasites
  • Drink water that has parasites in it
  • Eat raw or undercooked meat, especially lamb, pork, or venison
  • Use utensils that have been contaminated by raw meat
  • Eat unwashed fruits or vegetables

You also could be exposed to it if you’re an organ donor or have had a blood transfusion.

If you have signs of toxoplasmosis, see your doctor. You also might want to talk with them about it if you want to get pregnant or you have a health problem that affects your immune system.

If you have the infection, your body will make things called antibodies to try to fight it off. To find out if you have toxoplasmosis, your doctor can do a blood test to see if you have those antibodies.

If you’ve been infected recently, your body may not have had time to make them. So even if your test doesn’t show any signs of them, your doctor may want to do another test a few weeks later to be sure.

If the blood test shows you do have the antibodies, you’re likely in for another test. The CDC recommends that a lab that specializes in toxoplasmosis test your blood sample again to make sure the result is correct. If so, more tests can be done on your blood to find out when the infection started.

If you have a serious illness such as encephalitis (a life-threatening brain infection), you may need imaging tests to check for cysts or lesions in your brain. These tests may include an MRI or a brain biopsy. With an MRI, you lie inside a machine that creates images of your brain and head using a magnetic field and radio waves. With a brain biopsy, a doctor takes a sample of brain tissue and has it checked for toxoplasmosis cysts.  

If you find out you have toxoplasmosis while you’re pregnant, your doctor will want to see if it has passed to your baby. They may recommend one of these:

Ultrasound. This uses sound waves to make images of the baby. It can show if fluid has built up in the brain, among other signs.

Amniocentesis. Your doctor will use a long, thin needle to take a small bit of fluid from the area around the baby (the amniotic sac). The fluid will be tested for signs of the infection. You’ll need to be at least 15 weeks along before this test is done.

Toxoplasmosis doesn’t cause problems for most people, so you probably won’t need treatment for it if your immune system is healthy. If you are HIV-positive  or have AIDS, your doctor may recommend the antibiotic sulfadiazine, along with a medication usually used to treat malaria  called pyrimethamine (Daraprim).

For a pregnant woman whose baby hasn’t been affected, the doctor might prescribe an antibiotic called spiramycin. It’s used to treat toxoplasmosis in Europe but is still being tested in the United States.

If your baby is also infected or is likely to be, the doctor may recommend sulfadiazine and pyrimethamine, but only after the 16th week of pregnancy. Your doctor will watch the baby closely for signs of problems.

If your immune system is normal,  toxoplasmosis is likely to not cause any complications. You’re at greater risk for serious health problems from toxoplasmosis infection if:

  • You have HIV or AIDS.
  • You are having chemotherapy, which affects your immune system.
  • You’re taking steroids or other drugs with the side effect of suppressing your immune system.

If you have a weakened immune system (especially because of HIV or AIDS), toxoplasmosis can be serious and cause seizures or encephalitis. People who have AIDS or encephalitis that isn’t treated can die from toxoplasmosis. Children with toxoplasmosis may have hearing loss, blindness, and mental disabilities. 

You can do a few things to keep from coming into contact with the parasite:

  • Wear gloves and wash your hands thoroughly after working outdoors or in a garden.
  • If you have a sandbox, keep it covered to keep cats out of it.
  • Thoroughly clean your hands, counters, cutting boards, utensils, and dishes with warm water and soap after preparing raw meat.
  • Make sure food is cooked well, fruit and vegetables are thoroughly washed, and any water you drink has been treated.
  • Avoid drinks that include things like unpasteurized goat’s milk and raw eggs.

If you have a cat, here are few tips to make sure you and your family are safe around your feline friend:

  • Keep your cat indoors so it doesn’t pick up the parasite.
  • Do your best to keep your cat off counters where food is prepared.
  • Feed your cat only dry or canned cat food. Cats can get it from raw or undercooked meat.
  • Don’t touch stray cats or kittens.
  • Clean the litter box every day.
  • Only people who are healthy and aren’t pregnant should clean the litter box.
  • Wear gloves when you clean the litter box, and wash your hands with soap and warm water.
  • Boil the litter scoop in water for 5 minutes after each cleaning.

For most healthy adults, toxoplasmosis doesn’t pose any problems. But women who are pregnant or people with compromised immune systems will have to take special care. People with AIDS who have recovered from toxoplasmosis are at a high risk for getting it a second time. To prevent this, they must take medication as long as their immune system is compromised.

Children with toxoplasmosis who are treated at birth may not show any signs of the disease. If a pregnant woman is treated, the chances of the baby getting it drops 60%.