Toxoplasmosis

Overview

What is toxoplasmosis?

Toxoplasmosis is an illness caused by an infection with the parasite Toxoplasma gondii (T. gondii). The parasite reproduces in the intestinal tracts of cats. Humans become infected by direct or indirect contact with cat poop (feces) or by eating undercooked meat.

Most people don’t have symptoms when they get infected. But as your immune system attacks the parasite, it creates cysts in your body. The parasite can live inactive (dormant) in these cysts and make you sick when it reactivates at a later time.

Who does toxoplasmosis affect?

While T. gondii can infect anyone, most people won’t have symptoms. Your body usually fights off the parasite without you knowing it was there. Toxoplasmosis is most dangerous in pregnancy and for those with weakened immune systems, like people living with HIV or cancer.

While T. gondii needs cats to reproduce, cat ownership itself doesn’t seem to increase your risk of infection significantly.

Toxoplasmosis in pregnancy

If you get toxoplasmosis during pregnancy or shortly before getting pregnant, you can pass the parasite through the placenta to the fetus. This increases the risk of miscarriage, stillbirth or serious health problems for your future child. Complications of being born with toxoplasmosis include vision problems, blindness, developmental delays and learning differences.

Toxoplasmosis when you’re immunocompromised

If you’re living with HIV or cancer or if you’re taking immune-suppressing medications, your immune system can’t fight off infections like _T. gondii. _This means you have a compromised immune system (immunocompromised).

While most people can fight off toxoplasmosis without symptoms, a new or reactivated infection can cause life-threatening complications in someone with a weakened immune system.

If you’ve had toxoplasmosis in the past, T. gondii lives in cysts in your body. When your immune system is weakened, it can reactivate and cause you to get sick.

Left untreated, toxoplasmosis can cause organ damage in someone with a compromised immune system. This can eventually lead to death.

How common is toxoplasmosis?

Worldwide, it’s estimated that up to 1 in 3 people are infected with (T. gondii), the parasite that causes toxoplasmosis. Most people who are infected don’t have any symptoms.

Symptoms and Causes

What causes toxoplasmosis?

Toxoplasmosis is caused by an infection by the parasite T. gondii. Humans get toxoplasmosis after accidentally eating (ingesting) something contaminated with the parasite.

Because of the way the parasite hides in your body, you can have symptoms of toxoplasmosis when you’re initially infected or at a later time. When the parasite initially enters your body, some people get flu-like symptoms. But in most cases, your immune system can get rid of the initial infection without causing any symptoms.

While your immune cells are fighting it off, T. gondii makes small sacs (cysts) in your body. It can live in these cysts, inactive (dormant), for long periods of time. Research suggests that the cysts break open periodically and your body fights off the infection. Like the initial infection, this usually causes no symptoms.

If your immune system is weakened, though, these ruptured cysts can cause a new case of toxoplasmosis (reactivation).

How do you get toxoplasmosis?

You typically get toxoplasmosis from ingesting something contaminated with the parasite T. gondii.

T. gondii reproduces in a cat’s intestines and ends up in their poop. Cat poop can contaminate soil, water, plant material and the food we eat.

You can accidentally ingest T. gondii after coming in contact with something that’s contaminated, such as:

  • Cleaning a cat’s litter box.
  • Gardening in soil where cats live.
  • Drinking water that hasn’t been boiled or treated.
  • Eating unwashed fruits or vegetables.
  • Eating undercooked or improperly refrigerated meat.

Toxoplasmosis isn’t contagious, but a pregnant person can pass the parasite that causes it to a fetus. You can also get toxoplasmosis after receiving an infected organ transplant or blood transfusion, though this is rare.

What are the symptoms of toxoplasmosis in humans?

The symptoms of toxoplasmosis depend on where the parasite is active. This tends to be different depending on whether it’s a new (acute) infection, a reactivation or present at birth (congenital).

Ocular toxoplasmosis (toxoplasmosis of the eye) symptoms

Ocular toxoplasmosis is an infection of T. gondii in one or both eyes. It’s most common in teens or young adults who were born with a T. gondii infection. Rarely, ocular toxoplasmosis happens when you’re first infected with T. gondii. Symptoms of ocular toxoplasmosis include:

  • Eye pain.
  • Blurred vision
  • Blindness.

Acute toxoplasmosis symptoms

Acute toxoplasmosis is your body’s response to an initial infection with T. gondii. Most people don’t feel sick, but you might have flu-like symptoms, including:

Reactivated toxoplasmosis symptoms

If you have a weakened immune system (immunocompromised), you might have had a previous T. Gondii infection that reactivates when your body is no longer able to fight off infections easily. This includes people living with AIDS or cancer, or those on medications that suppress the immune system. Reactivated toxoplasmosis usually causes symptoms related your brain and spinal cord (central nervous system or CNS). CNS symptoms can include:

Congenital toxoplasmosis symptoms

Congenital (present at birth) toxoplasmosis is passed from a pregnant person to their unborn child. Some babies won’t have any symptoms at birth, but are at high risk for developing them later on. These symptoms may include:

  • Yellowish skin and eyes (jaundice).
  • Rash.
  • Enlarged liver and spleen (hepatosplenomegaly).
  • Vision loss, eye pain or sensitivity to light (retinochoroiditis).
  • Calcium deposits in their brain.
  • Fluid on the brain (hydrocephalus).
  • Small head size (microcephaly).
  • Seizures.
  • Delays in motor skill development.
  • Learning delays or differences.
  • Ocular toxoplasmosis.

Diagnosis and Tests

How is toxoplasmosis diagnosed?

To diagnose toxoplasmosis, your healthcare provider will perform a physical exam and ask you about your symptoms. They may order blood tests, biopsies, imaging (CT scan or MRI), a lumbar puncture or, if you’re pregnant, amniocentesis or ultrasound.

What tests will be done to diagnose toxoplasmosis?

To diagnose toxoplasmosis, your healthcare provider may order some or all of these tests:

  • Blood tests: Blood tests are almost always performed to diagnose toxoplasmosis. Your provider uses a needle to take blood from your vein, which they then send to a lab to look for antibodies to T. gondii. They may also look for parts of the parasite (DNA).
  • Biopsy: Rarely, your healthcare provider may take a small amount of tissue and send it to a lab to look for signs of T. gondii.
  • Imaging: If your healthcare provider suspects that you have toxoplasmosis in your brain, they may have a CT scan or MRI performed. This is where you lie down in a machine that takes pictures of your brain. Your provider reviews the images to see if there are any changes that indicate toxoplasmosis.
  • Lumbar puncture: If your healthcare provider suspects that you have toxoplasmosis in your brain or spinal cord, they may perform a lumbar puncture. In this procedure, your provider uses a needle to draw cerebrospinal fluid (CSF) from your lower back. It will be sent to a lab to look for signs of T. gondii.
  • Amniocentesis: If you’re pregnant and have been diagnosed with toxoplasmosis, your healthcare provider may recommend an amniocentesis. Your provider uses a small needle to collect cells from the fluid surrounding your unborn baby. It will be sent to a lab to look for signs of T. gondii.
  • Ultrasound: If you’re pregnant and have been diagnosed with toxoplasmosis, your healthcare provider may recommend an ultrasound. During an ultrasound, your provider passes a hand-held device over your abdomen to get images of the fetus. This can’t diagnose toxoplasmosis on its own, but it can show changes to in the fetus's brain that could indicate an infection.

Management and Treatment

How is it toxoplasmosis treated?

Toxoplasmosis is treated with a combination of anti-parasitic medicines and antibiotics. These stop T. gondii from growing and reproducing in your body.

Folinic acid is given during toxoplasmosis treatment to reduce the side effects of the anti-parasitic medications.

Toxoplasmosis isn’t usually treated in people who don’t have a compromised immune system and don’t have any symptoms. Treatment for toxoplasmosis can only work when parasites are active. It can’t get rid of the cysts the parasites leave in your body.

What medications are used to treat toxoplasmosis?

These medications are typically used to treat toxoplasmosis:

How soon after treatment will I feel better?

Most treatment plans for toxoplasmosis last two to six weeks, but you may start to feel better in only a few days. It may take three weeks to six months for brain injuries caused by the parasite to fully resolve.

Even if you feel better, you may have to stay on treatment for a long time to make sure the active parasites have been destroyed. If you’re pregnant and have been diagnosed with toxoplasmosis, you’ll probably have to take medication for the rest of the pregnancy. Treatment for congenital toxoplasmosis can last up to a year. Treatment in those with weakened immune systems can be given indefinitely.

How do I take care of myself with toxoplasmosis?

If you’re pregnant and have been diagnosed with toxoplasmosis, follow your healthcare provider’s recommendation to reduce the risk of passing it to the fetus.

If you have a weakened immune system and have been diagnosed with toxoplasmosis, you and your healthcare provider can make a plan for treating toxoplasmosis while managing any other underlying conditions.

Prevention

How can I prevent toxoplasmosis?

Safe food preparation and hand washing are the most important things you can do to help prevent toxoplasmosis.

  • Follow safe freezing and cooking practices before eating meat.
  • Peel fruits and vegetables or wash thoroughly before eating.
  • Wash cutting boards, counters, utensils and dishes with soapy water after use.
  • Don’t drink unpasteurized milk.
  • Don’t eat raw or undercooked clams, oysters or mussels.
  • Don’t drink untreated water.
  • Wear gloves when gardening and while working with soil or sand. Wash hands with soap and water afterward.
  • Cover outdoor sandboxes.
  • Don’t feed cats raw or undercooked meats.
  • Change cat litter daily. Wear gloves and wash your hands with soap and water afterward.
  • Keep cats indoors.

If you’re pregnant or have a compromised immune system:

  • Avoid changing cat litter yourself if possible.
  • If you must change cat litter, wear disposable gloves and wash your hands thoroughly afterward.
  • Don’t adopt a new cat or take in a stray cat

Outlook / Prognosis

What is the outlook for toxoplasmosis?

The outlook for toxoplasmosis varies. People with healthy immune systems rarely develop serious complications from toxoplasmosis.

In congenital toxoplasmosis, more than 70% of children will reach developmental milestones as expected with prompt treatment.

In patients with a weakened immune system, toxoplasmosis is most often found in the brain. With treatment, survival rates are at least 70%. Without treatment, toxoplasmosis of the brain is fatal.

Does toxoplasmosis ever go away?

Because of the cysts left behind by T. gondii, toxoplasmosis may never be fully cured. Medication can treat an active infection, but it doesn’t destroy the cysts.

If you have a healthy immune system, the cysts shouldn’t reactivate. But if you have a weakened immune system or if you have congenital toxoplasmosis, the parasite can reactivate and make you sick in the future.

Living With

How do I take care of myself with toxoplasmosis?

If you’ve been diagnosed with toxoplasmosis, keep an eye on your symptoms. Whether you’ve been prescribed treatment or not, call your healthcare provider if they don’t improve or get worse.

If your child was diagnosed with toxoplasmosis at birth, work closely with their pediatrician to make sure they get appropriate treatment. Follow up even after treatment is done on their provider’s recommended schedule. Know what signs of reactivation to look for.

When should I see my healthcare provider?

If you’re pregnant or plan to become pregnant or if you have a compromised immune system, you should talk to your healthcare provider about steps you can take to prevent toxoplasmosis in yourself or your future child.

If you have symptoms of toxoplasmosis, especially if you have a compromised immune system, contact your provider right away.

What questions should I ask my doctor?

  • What special precautions should I take to prevent toxoplasmosis?
  • How can I prevent transmission of toxoplasmosis during pregnancy?

Frequently Asked Questions

How do I know if my cat has toxoplasmosis?

Like humans, cats often don’t show any symptoms of toxoplasmosis. Ask your veterinarian if you have questions about toxoplasmosis in your pet cat.

What percent of cat owners have toxoplasmosis?

Since there are usually no symptoms, it’s difficult to determine what percentage of cat owners have toxoplasmosis. However, research suggests that cat ownership itself doesn’t put you at significantly higher risk than others.

Do I have to get rid of my cat if I’m pregnant or have a weakened immune system?

No, you don’t necessarily have to get rid of your cat if you’re pregnant or have a weakened immune system. Cat lovers can take precautions to reduce the risk of toxoplasmosis.

Keeping your cat indoors, having someone else change the litterbox frequently and not feeding your cat raw or undercooked meat all reduce the risk of you and your cat getting toxoplasmosis. If you do have to change the litterbox, wear gloves and a mask and wash your hands immediately after.

Finally, don’t take in stray cats or adopt a new cat while you’re pregnant or have a weakened immune system.

A note from Cleveland Clinic

Toxoplasmosis isn’t typically a serious illness, but it’s a unique threat to people during pregnancy or those who have compromised immune systems. Fortunately, there are many ways to help prevent an infection. Talk to your healthcare provider about how to reduce your risk of toxoplasmosis based on your specific circumstances.

Last reviewed by a Cleveland Clinic medical professional on 08/02/2022.

References

  • Centers for Disease Control and Prevention. Parasites – Toxoplasmosis (Toxoplasmosa infection). (https://www.cdc.gov/parasites/toxoplasmosis/) Accessed 8/2/2022.
  • Kim K. Toxoplasma Infections. In: Loscalzo J, Fauci A, Kasper D, Hauser S, Longo D, Jameson J. eds. Harrison's Principles of Internal Medicine 21e. McGraw Hill; 2022. Accessed 8/2/2022.
  • Merck Manuals. Toxoplasmosis. (https://www.merckmanuals.com/professional/infectious-diseases/extraintestinal-protozoa/toxoplasmosis) Accessed 8/2/2022.
  • Rosenthal PJ. Toxoplasmosis. In: Papadakis MA, McPhee SJ, Rabow MW, McQuaid KR. eds. Current Medical Diagnosis & Treatment 2022. McGraw Hill; 2022. Accessed 8/2/2022.
  • StatPerls. Toxoplasmosa Retinochoroiditis. (https://www.ncbi.nlm.nih.gov/books/NBK493182/) Accessed 8/2/2022.
  • Vittecoq M, Lafferty KD, Elguero E, et al. Cat ownership is neither a strong predictor of Toxoplasma gondii infection nor a risk factor for brain cancer. (https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3497129/#RSBL20120625C4) Biol Lett. 2012;8(6):1042. Accessed 8/2/2022.

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