Reconsidering the pathogenesis of ocular toxoplasmosis

PURPOSE: To review recent observations regarding the sources of Toxoplasma gondii infection and rates of ocular involvement in cases of infection acqu ired after birth, and to reconcile them with older observations and widely held beliefs about the pathogenesis of ocular toxoplasmosis. METHOD: A review of pertinent reports from the medical literature. RESULTS: There are several potential sources and routes of infection, inclu ding inhalation of spores and ingestion of contaminated drinking water, tha t were previously unrecognized, Ocular involvement in cases of acquired inf ection appears to be more common than heretofore believed. A variety of hos t and parasitic factors may influence rates of ocular infection and the cha racteristics of ocular disease. CONCLUSIONS: The scars from which recurrent toxoplasmic retinochoroiditis a rise may be the result of remote, acquired infections in many cases, rather than the residua of congenital infections, as commonly assumed. A better u nderstanding of the epidemiology of T. gondii infection, as well as the hos t and parasitic factors that influence disease presentation, is important f or developing strategies for prevention and management of ocular toxoplasmo sis. (Am J Ophthalmol 1999;128: 502-505. (C) 1999 by Elsevier Science Inc. All rights reserved.).