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Toxoplasmosis

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Definition:

Toxoplasmosis is an infection with the protozoan intracellular parasite Toxoplasma gondii .

Causes, incidence, and risk factors:

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.

References:

Cohen J, Powderly WG. Infectious Diseases . 2nd ed. New York, NY: Elsevier; 2004.

Mandell GL, Bennett JE, Dolin R. Principles and Practice of Infectious Diseases . 6th ed. London: Churchill Livingstone; 2005.

• Review Date: 2/13/2006
• Reviewed By: Monica Gandhi, M.D., M.P.H., Assistant Professor, Division of Infectious Diseases, UCSF, San Francisco, CA. Review provided by VeriMed Healthcare Network.

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