Toxoplasmosis choroiditis
 

There are multiple well-defined chorioretinal scar with pigmentary changes. If the lesion is acitve, the surrounding retinal has white fluffy edge and the vitreous contains cells. The adjacent retinal vessels may show sheathing from inflammation. Other signs: If the macula or optic disc is involved, the patient may have strabismus due to amblyopia If the lesion contains vitreous band, consider toxocara

Questions:

1. What organism causes toxoplasmosis?

Answer
It is an obligate intracellular protozoan Toxoplasma gondii. The cat is the definite host whereas the humans are incidnetal hosts. The infections may be congenital or acquired through ingentions of oocysts or brandyzoites from uncooked meat or contact with cat faeces.
 

2. Which factors are important in congenital toxoplasmosis?

Answer
When a pregnant woman becomes infected with toxoplasma the foetus has about 40% risk of acquiring the disease in utero. The risk is greatest in the first trimester.
 

3. What are the indications for treating active toxoplasmosis choroiditis?

Answer
It is a self-limiting disease and peripheral lesions usually require no treatment. Any associated anterior uveitis can be treated with topical steroid and mydriatic. The indications for systemic treatment are:
Lesions affecting the disc, macula or papilloedema bundle
Severe vitritis
Lesions threatening a major vessel
All lesions in immunocompromised individuals.

A variety of reime have been tried:

pyrimethamine/sulphadiazine/prednisolone plus folic acid supplement or
clindamycin/sulphadiazone/predinosolone or
cotrimoxazole/prednisolone
Steroid alone should be avoided as it can lead to a fulminant course.

Return to the main page