In a patient with AIDS chorioretinitis is typically caused
**Core Concept**
Chorioretinitis in a patient with AIDS is a manifestation of opportunistic infections that take advantage of the compromised immune system. The condition is characterized by inflammation of the choroid and retina, leading to vision loss.
**Why the Correct Answer is Right**
The correct answer is **Toxoplasma gondii**. This parasite is a common cause of chorioretinitis in immunocompromised patients, particularly those with AIDS. The pathogenesis involves the parasite's ability to evade the host's immune system, leading to the formation of retinochoroidal scars. The parasite's cysts can reactivate in the retina, causing a localized inflammatory response that results in chorioretinitis.
**Why Each Wrong Option is Incorrect**
**Option A:** Cytomegalovirus (CMV) is another opportunistic pathogen that can cause retinitis in patients with AIDS, but it is not the most common cause of chorioretinitis.
**Option B:** Cryptococcus neoformans is a fungus that can cause choroiditis, but it is not typically associated with chorioretinitis in AIDS patients.
**Option D:** Histoplasma capsulatum is a fungus that can cause choroiditis, but it is not commonly associated with chorioretinitis in immunocompromised patients.
**Clinical Pearl / High-Yield Fact**
Toxoplasma gondii is a common opportunistic pathogen in patients with AIDS, and chorioretinitis is a hallmark of its reactivation in the retina. The condition is often bilateral and can lead to significant vision loss if left untreated.
**Correct Answer:** C. Toxoplasma gondii