Toxoplasmosis is caused by a parasite that lives and multiplies in cats.
A fetus may be born prematurely, and a newborn may have problems such as a small head or an enlarged liver.
Blood tests and tests of other fluids can be done to detect the infection in the fetus, newborn, or mother.
The infection may cause death in some children and long-term neurologic problems in others.
Pregnant women should avoid cat litter and should thoroughly cook meat before eating it.
Antiparasitic drugs may be given to fetuses or newborns to treat the infection.
The Toxoplasma gondii parasite lives and multiplies mainly in cats, and its eggs are shed in cat feces. Cat feces can contaminate food, soil, and water. Pregnant women become infected if they swallow Toxoplasma eggs after they touch contaminated cat litter, soil, or other objects and then touch their mouth or handle and eat food without washing their hands. Pregnant women can also become infected if they consume raw or undercooked meat or other foods that are contaminated. Fetuses become infected if Toxoplasma gondii crosses the placenta (the organ that provides nourishment to the fetus) during pregnancy.
Women who were infected before pregnancy typically do not pass the parasite on to their fetus unless their immune system has been weakened (for example, by HIV infection), reactivating the infection.
Infection in the fetus is more severe if the fetus is infected earlier in pregnancy.
Life Cycle of Toxoplasma gondii
The fetus may grow slowly and be born prematurely.
At birth, newborns usually do not have symptoms, but they may have a number of problems, including
Children born with congenital toxoplasmosis may be severely ill and die shortly after birth, or they may have no symptoms until months or years later. Some never become ill.
The diagnosis of toxoplasmosis in a pregnant woman is usually based on blood tests that detect antibodies against the parasite. (Antibodies are proteins produced by the immune system to help defend the body against attack, including by parasites.)
To determine whether a fetus has been infected, a doctor can take a sample of the fluid around the fetus (amniotic fluid) and test it for antibodies to the parasite and for the parasite's genetic material (DNA). The test, a procedure called amniocentesis, is usually done after the 14th week of pregnancy.
In some states, the infection is found in seemingly healthy newborns during routine newborn screening tests using a dried blood spot. If doctors suspect a newborn is infected, they test the blood and the fluid that surrounds the brain and spinal cord (spinal fluid). To obtain spinal fluid, doctors do a spinal tap (lumbar puncture). Other body fluids and the placenta may also be tested. Doctors do imaging tests, such as computed tomography (CT) or magnetic resonance imaging (MRI), of the brain to look for abnormalities typical of toxoplasmosis. Newborns are also given a thorough eye examination by an ophthalmologist (a medical doctor who specializes in the evaluation and treatment of all types of eye disorders) and hearing tests.
Some children have a severe infection and die early, whereas others survive but have long-term neurologic problems. Occasionally, neurologic problems (such as intellectual disability, deafness, and seizures) or eye problems such as chorioretinitis, develop years later in children who appeared normal at birth. Therefore, children with congenital toxoplasmosis should be closely monitored by doctors beyond infancy.
Pregnant women should avoid handling cat litter. If this is not possible, pregnant women should change the entire litter box every day because the toxoplasmosis eggs do not become infectious for about 24 hours after the cat excretes them. Woman also should wear gloves and then carefully wash their hands to reduce the risk of infection.
Pregnant women should thoroughly cook meat before eating it. Fruits and vegetables should be washed thoroughly or peeled, and all food preparation should be followed immediately by handwashing.
To reduce the risk of transmitting the infection to the fetus, infected pregnant women may be give the drug spiramycin. However, this drug does not treat the fetus.
Pyrimethamine and sulfonamides may be given later in pregnancy if the fetus is infected.
Infected newborns with and without symptoms are treated with pyrimethamine, sulfadiazine, and leucovorin (a drug that prevents side effects of pyrimethamine).
Inflammation of the eyes is sometimes treated with corticosteroids.