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DESCRIPTION: A type of granulomatous uveitis caused by a protozoan parasite (Toxoplasma gondii); rats, birds, or humans can become infected by ingesting the parasite which is found in cat feces; ingestion of raw meat is another source of the disease. There are two types: congenital and acquired. The congenital type is a result of intrauterine infection; the inflammatory process is more severe and is often bilateral; chorioretinitis is almost always present. Cerebral involvement, with radiopaque calcification and mental retardation occurs in about 10% of the congenital types. The acquired type may appear at any age and is usually milder; it is often unilateral and frequently does not involve the central nervous system. The eye may not even be involved in the acute stage, but chorioretinitis may occur in the chronic form. Typically, the chorioretinitis progresses to a healed stage, leaving scars on the retina and choroid. If the macula has been involved, loss of central vision is permanent. The condition is not progressive, but usually chronic; new lesions may develop later.

(see also Chorioretinitis)

TREATMENT: Treatment is first with anti-infective drugs and then with corticosteroids if the initial treatment is ineffective. Prognosis for cure is fair to poor; visual impairment depends on the location of the healed scars (i.e., macula or periphery).

Educational adaptations include the use of magnification.

IMPLICATIONS: Pregnant women who own cats should refrain from handling the litter during pregnancy, since the fetus could become infected in utero. All cat owners should exercise caution in disposing of cat litter; scrupulous personal cleanliness is essential. Children who have cats as pets should be encouraged to wash their hands often, especially after caring for their cats.

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