What is the role of toxoplasma retinochoroiditis in the ocular manifestations of HIV infection?

Updated: Jun 12, 2019
  • Author: Robert A Copeland, Jr, MD; Chief Editor: Andrew A Dahl, MD, FACS  more...
  • Print
Answer

Answer

Toxoplasmosis is the most common cause of retinochoroiditis, accounting for about 30-50% of all posterior uveitis cases. Ocular manifestation usually follows systemic disease.

Infection with T gondii may be congenital, but most cases are acquired later in life. T gondii is an intestinal parasite in cats. The organism usually forms cysts that contain many organisms. The cysts may exist in 1 of 3 forms: (1) oocysts, in cat feces; (2) tachyzoites, proliferative form; and (3) bradyzoites, encysted form. Infection in humans may occur either by inhalation or by consuming poorly cooked meat or unpasteurized milk that has been infested with the organism.

In general, toxoplasma infection is well tolerated in most tissues of the body, except the eyes. T gondii may remain as bradyzoites within an inactive chorioretinal scar until reactivated as a result of immunosuppression. The exact mechanism of reactivation has not been elucidated completely. However, it is the transformation of the bradyzoites into tachyzoites that allows for new infection of the retina and choroid, leading to recurrent retinochoroiditis.


Did this answer your question?
Additional feedback? (Optional)
Thank you for your feedback!