Toxoplasma gondii can cause problems if it infects people who have weak immune systems. These include those with HIV/AIDS, undergoing chemotherapy or having an organ transplant, and taking drugs that suppress the immune system, like steroids.
Healthy kids don’t need medicine to treat Toxoplasma infection, which usually goes away on its own. But babies with congenital toxoplasmosis and those with weakened immune systems may need anti-parasite medicines.
Symptoms
Toxoplasma gondii is a protozoal parasite that is found in animals and humans worldwide. It can cause serious illness in pregnant women and people with weak immune systems. Symptoms may include blurred vision, mental problems, or loss of coordination. People can get the parasite by eating meat contaminated with oocysts, or through contact with cat feces.
Most healthy adults with toxoplasmosis do not need treatment. But pregnant women infected with the disease can pass it to their baby through the placenta. Getting toxoplasmosis before or during pregnancy can lead to miscarriage or to the baby being born too soon or with low birth weight. It can also lead to problems later in life such as blindness or brain damage.
Babies who are infected with toxoplasma at birth are called congenital toxoplasmosis. Congenital toxoplasmosis can be caused by infection that happens late in the pregnancy (third trimester) or by passing the infection from mother to child before conception. The chances of the baby having problems are higher when the infection starts earlier in pregnancy and is more severe if it affects the central nervous system or eyes.
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If a woman with toxoplasmosis gets pregnant, she should talk to her health care provider right away. She can have a blood test done to check for antibodies against the parasite. If the blood test is positive, she should wait 6 months before trying to get pregnant again. A woman can also have an ultrasound to see if the baby is infected.
If a pregnant woman has symptoms of toxoplasmosis, her doctor can check for the infection in the amniotic fluid by doing an amniocentesis, which is done in the second trimester between 15 and 20 weeks of pregnancy. The doctor can also use an ultrasound to test the health of the baby and look for signs of toxoplasmosis, such as brain or eye problems. If the infection is detected, the doctor can give the mother drugs to help protect the baby. The drug regimen usually includes spiramycin and pyrimethamine. The doctor may also give the woman corticosteroids if there are severe eye or central nervous system symptoms.
Transmission
Although Toxoplasma gondii is found worldwide, most people infected with the parasite have no symptoms. This is due to the fact that in immunocompetent hosts, infection is latent. Infection can be confirmed with serologic testing, which detects antibodies in the blood that are produced in response to infection. Molecular testing such as PCR can also confirm infection.
People with weakened immune systems are more likely to become infected with Toxoplasma and develop symptoms. These include people with HIV/AIDS, as well as those taking medicines that suppress the immune system such as steroids or those undergoing organ transplants. Rarely, Toxoplasma can be transmitted from mother to fetus during pregnancy, causing congenital Toxoplasmosis.
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Transmission of Toxoplasma gondii between people usually occurs when contaminated food or water is consumed. Cooked meat is a common source of Toxoplasma, but the parasite can also be found in undercooked or raw meat, unpasteurized milk, and untreated drinking water. Kitchen utensils that come into contact with raw meat or unwashed fruits and vegetables can also be contaminated.
Oocysts of Toxoplasma are shed in the stool and can contaminate the environment. These oocysts can remain viable for months, if not years. Toxoplasma goes through a sexual cycle and the organisms infect cells within the intestinal epithelium. Over time, these organisms multiply and form tissue cysts. Mature oocysts are then shed in the stool and can infect new host cells.
Infection with Toxoplasma is latent until it is reactivated by a variety of circumstances. Rupture of a tissue cyst is the most common cause, but reactivation may occur as a result of infection with other protozoa such as Babesia, Pneumocystis Jirovecii, and Cytomegalovirus (CMV). Infection can be reactivated by the use of immunosuppressive drugs including corticosteroids, antilymphocyte serum and others.
The most dangerous form of Toxoplasmosis is acquired congenitally, when the infection is passed from a pregnant woman to her fetus. The most severe cases of congenital Toxoplasmosis occur when the infection is acquired early in pregnancy, and can lead to miscarriage or stillbirth. Infected infants may have symptoms such as seizures, enlarged liver and spleen and yellowing of the skin and eyes (jaundice). Congenital Toxoplasmosis can also lead to birth defects such as hydrocephalus, microphthalmia and cerebral palsy.
Prevention
In healthy people who get Toxoplasma infection, symptoms usually are mild and don’t require treatment. But it’s more serious in people whose immune systems aren’t working at full strength, such as those who have HIV or certain types of cancer. Women who get Toxoplasma during the first trimester of pregnancy can pass it to their babies, who may have severe problems with their eyes or brain. These symptoms don’t appear in babies at birth, but they often show up in adolescence or early adulthood.
After a person gets infected with Toxoplasma, the parasite remains dormant for a lifetime in their tissues and organs. But if that person has a weak immune system, the Toxoplasma can reactivate and cause more serious illness. This is especially likely for pregnant women or those with a health condition that lowers their immunity, such as HIV infection or cancer chemotherapy.
Symptoms of Toxoplasmosis can be difficult to detect, and many people infected don’t know they have it. Usually, the infection is diagnosed with blood tests that look for antibodies to Toxoplasma. Doctors can also test tissue or bodily fluids for the presence of Toxoplasma. These include a biopsy (removing tissue for examination in a lab) or cerebrospinal fluid (collected using a needle in the back of the head).
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Infected individuals can take steps to reduce their chances of getting more serious Toxoplasma infections. For example, they should use a food thermometer to make sure meat, fish and shellfish are cooked to safe internal temperatures. They should also wash utensils and cutting boards that come into contact with raw meat, shellfish or unwashed produce. And they should keep cats indoors to prevent them from contaminating food or water with T. gondii.
If a person’s symptoms are severe, they might need to be hospitalized for treatment with medication to prevent further complications, including encephalitis (a life-threatening brain infection). To check for cysts in the brain, doctors might perform an MRI or a brain biopsy. The MRI uses magnetic fields and radio waves to create pictures of the brain and brain, while a brain biopsy involves removing a small sample of tissue for testing.
Treatment
Most people with healthy immune systems recover from toxoplasmosis without treatment. People with weakened immune systems, such as those with HIV/AIDS or cancer, may require antibiotics to prevent the disease from reactivating. People who are pregnant or immunocompromised should avoid contact with cats, including stray ones. They should also wash cutting boards and hands after handling raw meat and wash fruits and vegetables thoroughly before eating them.
The first step in diagnosis is a blood test to look for antibodies to T. gondii. A positive result indicates that you have been infected with the parasite in the past. If your doctor suspects you have an active infection, he or she may order other tests, such as an imaging test such as a CT or MRI scan or a cerebrospinal fluid (CSF) test to detect T. gondii in the brain.
In some cases, a brain scan, such as PET or SPECT, can help distinguish between toxoplasmosis and other conditions that cause similar symptoms. These include primary central nervous system lymphoma, TB, cryptococcosis, and PML. In rare cases, a biopsy of tissue from the brain or other part of the body can be used to confirm the diagnosis of toxoplasmosis.
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Pregnant women who have an active toxoplasmosis infection are more likely to pass the parasite to their baby in the womb, which can lead to miscarriage or premature birth. If an infection is caught early in pregnancy, treating the woman can lower the risk of transmission to the fetus and reduce the chances of complications for the baby after birth.
If you are not pregnant, your doctor will not treat you for toxoplasmosis unless you have a weakened immune system. However, if you are undergoing chemotherapy for cancer or taking medications that suppress your immune system, such as steroids, your doctor will prescribe pyrimethamine and sulfadiazine to prevent the parasite from reactivating and causing illness.
Newborns and infants of mothers who have congenital toxoplasmosis can suffer from health problems, such as blindness, hearing loss, mental retardation, and death. They can be treated with antibiotics, such as clindamycin and a combination of pyrimethamine and sulfadiazine.
