Table 2 Cumulative incidence of symptomatic toxoplasma infection during childhood per 100 000 live births: present study and published estimates (95% CI).

Outcome	Present study*	Predicted from other studies
Congenital toxoplasma infection
Any (n = 21)	3.43 (2.38, 4.78)	2†‡ 2¶
Neurological impairment (n = 5)	0.82 (0.36, 1.60)	0.4†§
Ocular disease (n = 13)	2.11 (1.31, 3.23)	3†**
Postnatally acquired ocular toxoplasmosis (n = 11)	1.62 (0.93, 2.62)	Not available
Any ocular disease (congenital or postnatally acquired, n = 24)	3.73 (2.63, 5.14)	2.9††

*Figures differ from table 1 as numerator is children (<16 yeas) born in England and Wales and first presenting during study period. Includes two therapeutic abortions for toxoplasmosis.

†Assumes birth prevalence of congenital toxoplasma infection = 1/10 000 (0.7/10 000 live births in Massachusetts,²⁶ 0.8/10 000 Sweden,²⁷ based on neonatal screening studies that were assumed to detect 70% of congenitally infected infants).¹⁰,²⁷

‡Assumes risk of neurological or ocular symptoms by 5 years = 20%.²,³,⁵

¶Based on national surveillance study in 1989: 14 cases (not all severe) identified in one year in England and Wales.²⁸

§Four per cent of live born children with congenital toxoplasmosis had serious neurological impairment or died in early life (unpublished data from EMSCOT cohort, Freeman and Gilbert).

**Assumes risk of ocular lesions by 12 years of age is 30% in children identified by prenatal screening. Only a proportion of lesions are likely to be symptomatic.⁵,²⁴,²⁵

††From surveillance study of ophthalmologists in a population of 7 million. Figure gives cumulative incidence by 15 years for British born children. Lifetime incidence was 18/100 000 (10.8, 25.2).²⁹