Introduction:
Toxoplasma gondii infection may result in retinochoroiditis and vision impairment.

Aim of the study:
We conducted a long-term observation of symptoms and titres of serum anti-Toxoplasma IgG in children and adolescents. Thirty-four children (23 girls and 11 boys), aged one week to 18 years (mean 7.3 ±5.5 years) were observed for 2 to 17 years (mean 5.1 ±3.4 years). Diagnosis was based on detection of characteristic lesions in fundoscopy and positive serum anti-Toxoplasma IgG titres, and inflammation was confirmed by the leakage of dye in fluorescein angiography.

Results:
In seven children the lesions were present at birth; they were bilateral and larger than 1 DD, in six of them they were accompanied by central nervous system abnormalities, and two children presented strabismus. Central localisation of toxoplasmosis, causing vision impairment, and inflammation recurrence, were found with similar frequency in these seven as in the other 27 children. Serum anti-T. gondii IgG ranged from 13 U/l to 1170 U/l, and titres were significantly higher in acute inflammation than in remission: 178 U/l vs. 90 U/l, p = 0.0016. Recurrences (one to three episodes) were noticed in 22/34 children: in all seven and in 15 out of 27 other children.

Conclusions:
Ocular lesions in toxoplasmosis that initiated in foetal life were diffuse and led to progressive impairment of vision in childhood. Recurrence may be expected in more than half of all ocular toxoplasmosis cases despite antiparasitic treatment. Increase of serum anti-Toxoplasma IgG titre may indicate recurrence of retinochoroiditis.