Question

In a patient with AIDS, chorioretinitis is typically caused by:

• A. Cytomegalovirus
• B. Toxoplasma gondii
• C. Cryptococcus neoformans
• D. Histoplasma capsulatum

Hint:

Low CD4 count in AIDS plus a pizza-pie fundus appearance points to CMV retinitis.

Answer 1

The Correct Option is A

Step 1: Set the immune backdrop.
In AIDS, chorioretinitis (inflammation at the back of the eye) tends to show up only once the CD4 count has fallen very low, generally under 50 to 100 cells per microliter, which is when several dormant organisms reactivate.

Step 2: Recall the appearance that clinches CMV.
CMV retinitis has a very recognizable look on fundus exam, patchy white retinal necrosis with hemorrhages, sometimes called a pizza-pie fundus. It is by far the most common infectious cause of retinitis once CD4 counts crash in AIDS.

Step 3: Explain the reactivation mechanism.
CMV, like other herpesviruses, hides quietly in the body after first exposure. When T-cell immunity fails badly, as in late AIDS, the virus reactivates and spreads through blood to reach and damage the retina.

Step 4: Weigh the alternative organisms.
Toxoplasma gondii does cause retinochoroiditis and matters in AIDS, but it is more famous for brain abscesses, and it trails CMV as a cause of pure retinitis. Cryptococcus neoformans is the classic AIDS meningitis organism, eye involvement from it is uncommon. Histoplasma capsulatum mainly causes lung and blood-borne disease, and its eye link (ocular histoplasmosis syndrome) is a separate condition seen without AIDS.

Step 5: Conclude.
The organism that best fits AIDS-related chorioretinitis is Cytomegalovirus.
\[ \boxed{\text{Cytomegalovirus}} \]