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Updated: Aug 17, 2026

3-D Imaging and Analysis of Neurons Infected In Vivo with Toxoplasma gondii
Published on: December 9, 2014
Eye manifestations of congenital toxoplasmosis
M B Mets1, E Holfels, K M Boyer
1Department of Ophthalmology, Children's Memorial Hospital, Chicago, Illinois, USA.
Insights
Congenital toxoplasmosis can cause significant vision loss due to retinal damage, even with treatment. Early intervention with pyrimethamine and sulfadiazine helps control active lesions and prevent further vision impairment.
Area of Science:
- Ophthalmology
- Infectious Diseases
- Pediatrics
Background:
- Congenital toxoplasmosis, a parasitic infection, can lead to ocular complications.
- The long-term effects on vision and the natural history of the disease require further investigation.
Purpose of the Study:
- To determine the natural history of congenital toxoplasmosis in treated and untreated patients.
- To assess the impact of congenital toxoplasmosis on vision and visual acuity.
Main Methods:
- A prospective, longitudinal study involving 76 newborns treated with pyrimethamine and sulfadiazine.
- Inclusion of 18 historical patients not treated in their first year of life for comparison.
Main Results:
- Chorioretinal scars, particularly in the periphery, were common eye findings.
- Macular scars were prevalent, affecting visual acuity and leading to bilateral visual impairment in 29% of treated patients.
- Recurrences of active lesions were observed in both treated and untreated groups, with new lesions appearing in previously unaffected retinas.
Conclusions:
- Congenital toxoplasmosis often results in significant retinal damage and vision loss at birth.
- Treatment with pyrimethamine and sulfadiazine can render active lesions quiescent.
- Despite substantial retinal damage, vision can remain remarkably good in some cases, even with large macular scars.
Purpose:
To determine the natural history of treated and untreated congenital toxoplasmosis and impact of this infection on vision.
Methods:
In this prospective, longitudinal study, 76 newborns were treated with pyrimethamine and sulfadiazine for approximately one year, and 18 individuals not treated during their first year of life entered the study after age 1 year (historical patients).
Results:
Chorioretinal scars were the most common eye finding in all patients and were most common in the periphery (58% of treated and 82% of historical patients). Macular scars were present in 54% of the treated patients; 41% were bilateral. Macular scars were present in 76% of the historical patients; 23% were bilateral. Visual acuity in the presence of macular lesions ranged from 20/20 to 20/400. Of the patients followed up from the newborn period and treated, 29% had bilateral visual impairment, with visual acuity for the best eye of less than 20/40. Causes for this visual impairment in eyes with quiescent lesions included macular scars, dragging of the macula secondary to a peripheral lesion, retinal detachment, optic atrophy, cataract, amblyopia, and phthisis. There were recurrences in both treated (13%, 7/54) and previously untreated historical patients (44%, 8/18). The total, median, and range of years of follow-up during which recurrences were observed were, for treated patients, 189 years (total), five years (median) and three to ten years (range) and, for historical, untreated patients, 160 years (total), 11 years (median), and three to 24 years (range). New lesions occurred in previously normal retinas and also contiguous to older scars. Active lesions appeared to become quiescent within ten to 14 days after beginning pyrimethamine and sulfadiazine therapy.
Conclusion:
Many children with congenital toxoplasmosis have substantial retinal damage at birth and consequent loss of vision. Nonetheless, vision may be remarkably good in the presence of large macular scars. Active lesions become quiescent with treatment.
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