Epidemiology of ocular Toxoplasma

Abstract

Toxoplasma retinochoroiditis is a common cause of posterior uveitis and accounts for 20–90% of patients with posterior uveitis seen in tertiary referral clinics (see Table 1). Toxoplasma retinochoroidal lesions are commonly attributed to congenital infection except where there is clear evidence of acquired toxoplasmosis [1–5]. We challenge this view by comparing the epidemiological evidence on the characteristics and risks of ocular disease due to congenital and acquired toxoplasmosis. In summary, although the clinical appearances and serological findings are frequently indistinguishable, the age at onset of signs and symptoms helps to differentiate between congenital and acquired infection. Finally, information on the risks of ocular disease due to congenital and acquired toxoplasmosis provide broad and uncertain estimates but no evidence that the majority of cases are due to congenital infection. On balance, the available evidence suggests that at least two-thirds of Toxoplasma ocular disease may be due to acquired infection.