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: Recall what chorioretinitis means.
Chorioretinitis is inflammation of the choroid and retina, the layers at the back of the eye. In a patient with weak immunity, it usually signals an opportunistic infection reaching the eye through the bloodstream.

Step 2: Think about which organism causes this most often in AIDS.
In AIDS, chorioretinitis is most often caused by Cytomegalovirus (CMV), especially once the CD4 count drops below about 50 to 100 cells per microliter. CMV retinitis shows a classic pizza-pie or cottage-cheese-and-ketchup appearance on eye examination, with white areas of retinal necrosis and scattered hemorrhages, and it can lead to blindness if untreated.

Step 3: Explain why CMV specifically targets the eye here.
CMV is a herpesvirus that stays latent in the body after a first infection, and it reactivates once cell-mediated immunity collapses, which is exactly what happens in advanced AIDS. Once reactivated, it spreads through the blood and has a strong tendency to infect retinal cells.

Step 4: Rule out the other organisms.

(2) Toxoplasma gondii: Causes retinochoroiditis too, and is an important cause in AIDS, but it is classically linked more with brain lesions (toxoplasma encephalitis) and is less common than CMV as a cause of retinitis specifically.

(3) Cryptococcus neoformans: In AIDS, this organism is best known for causing meningitis, it can rarely affect the eye but is not the typical cause of chorioretinitis.

(4) Histoplasma capsulatum: Causes a fungal illness more linked with lung and disseminated disease, and with a different eye condition called presumed ocular histoplasmosis syndrome in non-AIDS patients, not classic AIDS chorioretinitis.

Final Answer:
Cytomegalovirus is the classic and most common cause of chorioretinitis in AIDS.
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