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Definition Return to top
Toxoplasmosis is an infection with the protozoan intracellular parasite Toxoplasma gondii.Causes, incidence, and risk factors Return to top
Toxoplasmosis is found in humans worldwide, and in many species of animals and birds. Cats are the definitive host of the parasite.
Human infection results from ingestion of contaminated soil, careless handling of cat litter, ingestion of raw or undercooked meat (lamb, pork, and beef), transmission from a mother to a fetus through the placenta (congenital infection), or by blood transfusion or solid organ transplantation.
Over 80-90% of primary infections produce no symptoms. The incubation period for symptoms is 1 to 2 weeks.
Congenital toxoplasmosis is caused by infection with Toxoplasma gondii in a pregnant woman, with up to 50% of such infections transmitted to the fetus. Signs of congenital infection may be present at birth or develop over the first few months of life.
Infants may show signs of central nervous system disorders, enlargement of the liver and spleen, blindness, and mental retardation. Toxoplasmosis also affects people who are immunosuppressed (as a result of AIDS, cancer, or immunosuppressive therapies). The disease may affect the brain, lung, heart, eyes, or liver.
Symptoms Return to top
In non-immunosuppressed people:
In congenital infection:
In an immunosuppressed person:
Signs and tests Return to top
Tests to determine infection or presence of cysts:
Treatment Return to top
No treatment is recommended for people without symptoms, except children, to prevent retinal inflammation. Treatment of women in pregnancy is controversial because of the toxicity of the medications, but treatment is still advocated.
Medications to treat the infection include: pyrimethamine, sulfonamide drugs, folinic acid, clindamycin, and trimethoprim-sulfamethoxazole. Treatment in AIDS patients is continued as long as the immune system is weak, to prevent reactivation of the disease.
Expectations (prognosis) Return to top
Acute infection in children may cause retinochoroiditis (inflammation of the retina). Toxoplasmosis in adults has a good prognosis (probable outcome) if the immune system is healthy. Chronic infection without any symptoms is usually benign (harmless).
Complications Return to top
Calling your health care provider Return to top
Call for an appointment with your health care provider if symptoms of toxoplasmosis occur. Urgent or emergency conditions exist if the disorder occurs in an immunosuppressed person or in a baby, or if confusion, seizures, or other severe symptoms develop.
Prevention Return to top
Avoid undercooked meats, or freeze meat to -20 degrees Celsius for 2 days. Protect children's play areas from cat and dog feces. Wash the hands thoroughly after contact with soil that may be contaminated with animal feces.
Pregnant women should have their blood examined for Toxoplasma antibody -- and those with negative results should take measures to prevent infection by avoiding exposure to cat feces (including not cleaning litter boxes), cooking meat thoroughly, and washing hands thoroughly after handling raw meat.
Patients with HIV disease should have toxoplasma antibody titers checked. If the results of the blood test are positive and if the CD4 count is less than 200, patients should be given prophylactic antibiotics (trimethoprim-sulfamethoxazole is the medication of choice).
Update Date: 2/3/2004 Updated by: Kenneth Wener, M.D., Division of Infectious Diseases, Beth Israel Deaconess Medical Center, Boston, MA. Review provided by VeriMed Healthcare Network.
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Page last updated: 28 October 2004 |