Ocular toxoplasmosis

Ocular toxoplasmosis is a frequent cause of posterior segment infection,probably accounting for at least 25% of cases in the United States. Most cases of ocnlar toxoplasmosis were earlier believed to result from recurrence of... 

Ocular toxoplasmosis is an important cause of posterior segment infection in older patients, with reports of disease presentation describing many atypical findings, including diffuse disease, multifocal lesions, and areas of involvement greater than three disc diameters in size. These individuals were not immunocompromised, but the disease severity was attributed to the decline in immune function that naturally occurs with aging. 

It should be noted that a recent, evidence-based, systematic review of published randomized clinical trials of therapy for toxoplasmic retinochoroiditis fitund only three studies that met the authors criteria for inclusion, two of which were carried out more than 35 years ago. Based on this evaluation the authors concluded that there was a lack of evidence to support routine antibiotic treatment for ocular toxoplasmosis, finding no evidence for a beneficial effect on the duration and severity of signs of the disease process. However, the preponderance of evidence supports the concept that appropriate antibiotic therapy is a community standard of care, which is bolstered by guidelines for treatment in many published sources, plus the responses of those practitioners recently surveyed about their preferred patterns of management of the condition. 

Two other agents show promise in treatment of ocular toxoplasmosis. Atovaquone, primarily used for mild to moderate episodes of Pneumocystis carinii pneumonia, has been effective in small series of patients with toxoplasmosis. It appears to have activity against both tachy-zoites and tissue cysts. More recent studies on atovaquone in toxoplasmosis are limited to murine models, and no further reports on this drug therapy in humans have been published. Azithromycin, a macrolide antibiotic, is efficacious against T. gondii and can also kill tissue cysts. A randomized study of 46 patients compared the combinations of azithromycin plus pyrimethamine versus pyrimethamine plus sulfadiazine in treatment of ocular toxoplasmosis efficacy was similar, but the azithromycin/ pyrimethamine regimen caused less adverse effects. 

Bosch-Driessen LH, Verbraak ED, Suttorp-Schulten MS, et al. A prospective, randomized trial of pyrimethamine and azithromycin vs pyrimethamine and sulfediazine for the treatment of ocular toxoplasmosis. Am J Ophthalmol 2002 134 34. 

Bosch-Driessen LE Berendschot TT, Ongkosuwito JV, et al. Ocular toxoplasmosis. Clinical features and prognosis of 154 patients. Ophthalmology 2002 209 869. 

Bosch-Driessen LH,Plaiser MB, Stilma JS, et al. Reactivations of ocular toxoplasmosis after cataract extraction. Ophthalmology 2002 109 41. 

Engstrom RE Jr, Holland GN, Nussenblatt RB, et al. Current practices in the management of ocular toxoplasmosis. Am J Ophthalmol 1991 1H 601. 

Gilbert RE, Stanford MR. Is ocular toxoplasmosis caused by prenatal or postnatal infection Br J Ophthalmol 2000 84 224. 

Holland GN. Ocular toxoplasmosis a global reassessment. Part I epidemiology and course of disease. Am J Ophthalmol 2003 136 973. 

SoheUian M, Sadoughi MM, Ghajarnia M, et al. Prospective randomized trial of trimethoprim/sulfamethoxazole versus pyrimethamine and sulfadiazine in the treatment of ocular toxoplasmosis. Ophthalmology 2005 112 1876. 

A 57-year-old Caucasian woman with a history of ocular toxoplasmosis, treated with intravitreal clindamycin (1 mg/0.1 ml) and dexamethasone (0.4 mg/0.1 ml), developed a generalized eiythematous macular rash over the scalp, face, arms, thighs, and trunk 2 days after the start of treatment (37). 

In a prospective, randomized, open, multicenter trial of pyrimethamine -I- azithromycin versus pyrimethamine + snlfadiazine for the treatment of ocular toxoplasmosis in 46 patients with sight-threatening ocular toxoplasmosis, the two regimens had similar efficacy however, the adverse effects were significantly less common and severe with pyrimethamine + azithromycin (2). 

An outbreak of acquired ocular toxoplasmosis involving 248 people in India was described by Balasundaram et al. (2010). The suspecfed source of fhe infection was municipal drinking water. 

Balasundaram, M. B., Andavar, R., Palaniswamy, M., and Venkatapathy, N. (2010). Outbreak of acquired ocular toxoplasmosis involving 248 patients. Arch. Ophthal. 128(1), 28-32. 

Garweg, J. G. and Candolfi, E. (2009). Immunopathology in ocular toxoplasmosis Facts and clues. Mem. Inst. Oswaldo Cruz 104, 211-220. 

---