Toxoplasmic retinochoroiditis--a historical review and current concepts

Toxoplasmic retinochoroiditis usually presents during the first three decades of life as a consequence of intra-uterine infection by Toxoplasma gondii. The ingestion of infected undercooked meat, or foodstuffs contaminated by infected cat faeces, constitute the primary sources of infection for the non-immune mother. It is thought that following congenital infection, Toxoplasma cysts remain dormant in otherwise normal retina and that acute retinochoroiditis is the result of reactivation of the parasite, perhaps by cyst rupture. Treatment is indicated for sight threatening disease and comprises anti-Toxoplasma agents. The addition of steroids may be required to diminish the inflammatory response. Photocoagulation of normal retina around focal lesions probably decreases the incidence of recurrent inflammation. Women should be advised not to eat undercooked meat and to avoid contact with cat excrement during pregnancy. These measures will decrease the incidence of both eye disease and the more severe manifestations of congenital toxoplasmosis, which include congenital abnormalities, mental retardation, hydrocephalus and blindness.