INCIDENCE OF ACUTE SYMPTOMATIC TOXOPLASMA RETINOCHOROIDITIS IN SOUTH LONDON ACCORDING TO COUNTRY OF BIRTH

Objective-To determine the incidence of acute symptomatic toxoplasma r etinochoroiditis presenting to ophthalmologists for patients born in B ritain and elsewhere. Design-Population based, cross sectional study. Setting-11 districts in south Greater London. Subjects-All patients pr esenting ophthalmologists with symptoms due toxoplasma retinochoroidit is in 1992-3. Main outcome measure-Intraocular inflammation in associa tion with a retinochoroidal scar, active adjoining retinitis, and IgG serum antibodies to toxoplasma. Results-The estimated incidence of acu te symptomatic retinochoroiditis for all people born in Britain was 0. 4/100 000/year and for black people born in west Africa 57/100 000/yea r. If a mean of two symptomatic episodes per lifetime is assumed, 100 people born in Britain may be affected each year, about a fifth of the estimated 500-600 congenitally infected people born each year. Conclu sions-A substantial proportion of people with acute symptomatic toxopl asma retinochoroiditis were born outside the country, and the number b orn in Britain was smaller than the number previously estimated to dev elop retinochoroidal lesions due to congenital toxoplasmosis. These fi ndings suggest that prenatal screening for toxoplasmosis in Britain ma y be of limited benefit.