National Toxicology Program

Overview

Toxoplasmosis is an infection caused by a parasite. If a pregnant woman contracts toxoplasmosis, there is a 40% chance that her unborn child will also become infected. However, such infections are not common in the United Sates. One to 2 per 1000 babies that are born each year have toxoplasmosis. The toxoplasmosis parasite may be found in cat feces, soils, and in undercooked infected meat. Cats may contract toxoplasmosis after eating infected birds or rodents, and the infection can spread to persons only through direct contact with the cat’s feces or soils in contact with the feces. Unborn children infected in early pregnancy are most likely to suffer severe health effects, which may include blindness, deafness, seizures, and mental retardation. Often, infected infants appear normal at birth, but develop symptoms months or years later. Toxoplasmosis is easily prevented by taking some simple precautions such as having someone else clean cat litter boxes, keeping cats indoors, thoroughly cooking meats and washing fruits and vegetables before eating, wearing gloves while gardening, and washing hands after handling raw meats. If toxoplasmosis is suspected in a pregnant woman, tests can be done to determine if the unborn child is also infected. Medications can prevent or reduce severity of health effects in unborn children.

Description of Toxoplasmosis

According to the Organization of Teratology Information Services (OTIS, 2002 ), "Toxoplasmosis is an infection caused by the parasite Toxoplasma gondii. You can get it by eating undercooked, infected meat, or handling soil or cat feces that contain the parasite. Swelling of the lymph nodes or a mononucleosis-type (fever, fatigue, and sore throat) illness may be seen. Most adults have no symptoms. In most cases, once you have gotten toxoplasmosis, you cannot get it again."

The March of Dimes (MOD 2001) has stated that, "Cats often become infected when they eat an infected rodent or bird. The parasite reproduces in the cat's intestine, and a form of the parasite ends up in the cat's litter box, sand or soil. This form of the parasite becomes infectious within days, and is resistant to most disinfectants. Under certain temperature and humidity conditions, the parasite may live in soil for more than a year. Infected cats usually appear healthy."

Toxoplasmosis and pregnancy

If a woman contracts toxoplasmosis during pregnancy, there is a possibility that her unborn child will be infected. Unborn children of women who have contracted toxoplasmosis prior to pregnancy are usually not at risk. According to OTIS (OTIS, 2002 ), "Congenital toxoplasmosis only occurs when the mother has an active infection during pregnancy. In general, there is no increased risk to the fetus when toxoplasmosis occurs more than 6 months prior to conception. If you had toxoplasmosis in the past, you are usually immune, and the fetus is not at risk."

The Organization of Teratology  Information Services (OTIS, 2002 ) has stated, "In about 40 percent of the cases in which a pregnant woman has toxoplasmosis, the baby is also infected. Infants who become infected during pregnancy are said to have 'congenital toxoplasmosis' infection. In the United Sates, 1 to 2 per 1000 babies that are born each year have toxoplasmosis." According to the March of Dimes (MOD 2001), About one in 10 infected babies has a severe Toxoplasma infection evident at birth. These newborns often have eye infections, an enlarged liver and spleen, jaundice (yellowing of the skin and eyes), and pneumonia. Some die within a few days of birth. Those who survive can have mental retardation, severely impaired eyesight, cerebral palsy, seizures and other problems. Although up to 90 percent of infected babies appear normal at birth, between 55 and 85 percent of them develop problems months to years later, including eye infections that may affect sight, hearing loss and learning disabilities. Toxoplasmosis during pregnancy also can result in miscarriage or stillbirth.

Toxoplasmosis prevention

To prevent toxoplasmosis, the March of Dimes (MOD 2001) suggests that pregnant woman take the following precautions:

• Don't empty the cat's litter box. Have someone else do this.
• Don't feed the cat raw or undercooked meats.
• Keep the cat indoors to prevent it from hunting birds or rodents.
• Don't eat raw or undercooked meat, especially lamb or pork. Meat should be cooked to an internal temperature of 160º F throughout.
• If you handle raw meat, wash your hands immediately with soap. Never touch your eyes, nose or mouth with potentially contaminated hands.
• Wash all raw fruits and vegetables before you eat them.
• Wear gloves when gardening, since outdoor soil may contain the parasite from cats. Keep your hands away from your mouth and eyes, and wash your hands thoroughly when finished. Keep gloves away from food products.
• Avoid children's sandboxes. Cats may use them as a litter box.

Diagnosis and Treatment

According to the March of Dimes (MOD 2001), "If a health care provider suspects that a pregnant woman has an active Toxoplamsa infection, he or she may recommend one or more of several available blood tests. These tests require expert interpretation and, therefore, the Centers for Disease Control and Prevention recommends that all positive test results be confirmed by a Toxoplasma reference laboratory (one with special expertise in diagnosing this disorder)".

If the reference laboratory confirms that a pregnant woman has an active infection, the next step is to determine whether the fetus is infected. Prenatal tests including amniocentesis and ultrasound may help to determine whether the fetus is infected. Fetuses suspected of being infected are treated by giving the mother pyrimethamine and sulfadiazine. This approach appears to reduce the frequency and severity of the newborn's symptoms. Time is of the essence and the earlier the treatment of the mother, the less likely her baby is to have symptoms.

If tests show that the fetus is not yet infected, the mother may be given an antibiotic called spiramycin. Some studies suggest that spiramycin can reduce by about 50 percent the likelihood of the fetus becoming infected. Although spiramycin has not yet been approved for use in this country by the Food and Drug Administration (FDA), and is therefore considered an experimental drug, it can be obtained from the FDA. Physicians who are interested in obtaining the drug can contact the FDA at 301/827-2335.

Further information on toxoplasmosis can be found on the Center for Disease Control's website at:http://www.cdc.gov/mmwr/preview/mmwrhtml/rr4902a5.htm or at: http://www.cdc.gov/ncidod/dpd/parasites/toxoplasmosis/factsht_toxoplasmosis.htm

Contacts for additional information

Additional information can be obtained from:
March of Dimes Resource Center

Your source of information on pregnancy and birth defects.
Toll-free: 888-MODIMES
TTY: 914-997-4764
Fax: 914-997-4763

URL: http://www.marchofdimes.com
E-mail: resourcecenter@modimes.org.

OTIS Information/Pregnancy Riskline
Box 144270
Salt Lake City, Utah  84114-4270

Telephone: (801) 328-BABY, Fax: (801) 538-6510.