Congenital toxoplasmosis is a disease that occurs in fetuses infected with Toxoplasma gondii (a protozoan parasite). It can cause miscarriage or stillbirth. It can also cause serious and progressive visual, hearing, motor, cognitive, and other problems in a child.
There are approximately 400 to 4,000 cases of congenital toxoplasmosis each year in the United States.
You can get the T. gondii parasites in several ways. For example, you can become infected by eating uncooked or undercooked meat or produce, or by drinking water that is contaminated with the parasites or their eggs, though it is rare to get the parasites from water in the United States. You can also get the parasites by touching contaminated soil or cat feces and then touching your mouth.
If you become infected with the parasites during your pregnancy, you can pass them to your unborn child during your pregnancy or delivery. This is what causes congenital toxoplasmosis.
You can keep your cat, even if it has the parasites. The risk of getting the parasites from your cat is very low, according to the Centers for Disease Control and Prevention. Make sure to have someone else change your cat’s litter box for the entire duration of your pregnancy.
If you become infected with the parasites during your first trimester of pregnancy, your baby has about a 15 to 20 percent chance of getting congenital toxoplasmosis. However, if you become infected during your third trimester, your unborn child has about a 60 percent chance of becoming infected, according to estimates by Boston Children’s Hospital.
Most infected infants appear healthy at birth. They often do not develop symptoms until months, years, or even decades later in life.
Infants with severe congenital toxoplasmosis usually have symptoms at birth or develop symptoms within the first six months of life.
Symptoms may include:
- premature birth (as many as 50 percent of infants with congenital toxoplasmosis are born prematurely)
- abnormally low birth weight
- eye damage
- jaundice (yellowing of the skin and whites of the eyes)
- difficulty feeding
- swollen lymph nodes
- enlarged liver and spleen
- macrocephaly (abnormally large head)
- microcephaly (abnormally small head)
- skin rash
- vision problems
- hearing loss
- motor and developmental delays
- hydrocephalus (a buildup of fluid in the skull)
- intracranial calcifications (evidence of areas of damage to the brain caused by the parasites)
- mild to severe mental retardation
Your doctor may perform a blood test to detect the parasites. If you test positive for the parasites, your doctor may perform the following tests during your pregnancy to determine if your unborn baby is also infected:
- ultrasound to check for fetal abnormalities, such as hydrocephalus
- polymerase chain reaction (PCR) amniotic fluid testing (although this test may produce false negative or false positive results)
- fetal blood testing
If your baby shows symptoms of congenital toxoplasmosis after birth, your doctor may perform one or more of the following tests:
- antibody test on the umbilical cord blood
- antibody test on your baby’s cerebrospinal fluid
- blood test
- eye exam
- neurological exam
- CT or MRI scan of your baby’s brain
Typically, some form of medication is used to treat congenital toxoplasmosis:
Medications Given During Pregnancy
- spiramycin (Rovamycine) to help prevent the transmission of the parasites from the mother to the fetus
- pyrimethamine (Daraprim) and sulfadiazine may be given after the first trimester if it has been confirmed that the fetus is infected with the parasites
- folic acid to protect from bone marrow loss in the mother and fetus caused by pyrimethamine and sulfadiazine
Medications Given to a Baby After Birth
- pyrimethamine, sulfadiazine, and folic acid (usually taken for one year)
- steroids if your baby’s vision is threatened or if your baby has high protein levels in his or her spinal fluid
In addition to medication, your doctor may prescribe other treatments, depending on your baby’s symptoms.
Your baby’s long-term outlook depends on the severity of his or her symptoms. The parasite infection generally causes more serious health problems to fetuses that contract it in early pregnancy, rather than in the late stages of development. If detected early, medications can be given before the parasites harm the fetus. Up to 80 percent of infants with congenital toxoplasmosis will develop visual and learning disabilities later in their lives. Some infants may experience vision loss and lesions in the eye 30 or more years after birth.
Most cases of congenital toxoplasmosis in the United States can be prevented if the mother engages in safe food practices.