Epidemiology and Infection

Incidence of symptomatic toxoplasma eye disease: aetiology and public health implications

R. E. GILBERT a1c1, D. T. DUNN a1, S. LIGHTMAN a2, P. I. MURRAY a3, C. E. PAVESIO a2, P. D. GORMLEY a2, J. MASTERS a1, S. P. PARKER a1 and M. R. STANFORD a4
a1 Department of Epidemiology and Public Health, Institute of Child Health, University College London Medical School, 30 Guilford Street, London WC1N 1EH, UK
a2 Department of Clinical Ophthalmology, Institute of Ophthalmology, Moorfield's Eye Hospital, City Road, London EC1 2PD, UK
a3 Academic Unit of Ophthalmology, The University of Birmingham, Birmingham and Midland Eye Centre, City Road NHS Trust, Dudley Road, Birmingham B18 7QU, UK
a4 Medical Eye Unit, St Thomas' Hospital, London SE1 7EH, UK


Ocular disease is the commonest disabling consequence of toxoplasma infection. Incidence and lifetime risk of ocular symptoms were determined by ascertaining affected patients in a population-based, active reporting study involving ophthalmologists serving a population of 7·4 million. Eighty-seven symptomatic episodes were attributed to toxoplasma infection. Bilateral visual acuity of 6/12 or less was found in seven episodes (8%) and was likely to have been transient in most cases. Black people born in West Africa had a 100-fold higher incidence of symptoms than white people born in Britain. Only two patients reported symptoms before 10 years of age. The estimated lifetime risk of symptoms in British born individuals (52% of all episodes) was 18/100000 (95% confidence interval: 10·8–25·2). The low risk and mild symptoms in an unscreened British population indicate limited potential benefits of prenatal or postnatal screening. The late age at presentation suggests a mixed aetiology of postnatally acquired and congenital infection for which primary prevention may be appropriate, particularly among West Africans.

(Accepted May 14 1999)

c1 Author for correspondence.