In diagnosis of AIDS, criteria include the following except -a) CD4 <200b) CD8 < 500c) CD 4 : CD 8 = 1d) Presence of any of the opportunistic infections tuberculosis,pneumosystic carinii, cytomegaloviruse) Western blot is positive
**Core Concept**
The diagnosis of AIDS involves a combination of clinical, immunological, and virological criteria. **Acquired Immunodeficiency Syndrome (AIDS)** is characterized by a weakened immune system, making the body susceptible to opportunistic infections. The **CD4:CD8 ratio** and **CD4 count** are crucial immunological markers.
**Why the Correct Answer is Right**
The correct answer is related to the specific immunological criteria used in the diagnosis of AIDS. A **CD4 count of less than 200 cells/μL** is a key indicator of AIDS. The **CD4:CD8 ratio** is also significant, with a ratio of less than 1 being indicative of immune suppression. The presence of **opportunistic infections** such as tuberculosis, Pneumocystis carinii, and cytomegalovirus is a clinical criterion. **Western blot** is a confirmatory test for HIV infection.
**Why Each Wrong Option is Incorrect**
**Option B:** CD8 < 500 is incorrect because an elevated CD8 count is often seen in HIV infection as a compensatory response, and a decrease in CD8 is not a criterion for AIDS diagnosis.
**Option C:** CD4:CD8 = 1 is incorrect because a ratio of less than 1 is more indicative of immune suppression.
**Option D:** Presence of any of the opportunistic infections is a correct criterion for AIDS diagnosis.
**Option E:** Western blot is positive is a correct virological criterion for HIV infection.
**Why Each Wrong Option is Incorrect (Continued)**
The incorrect options are those that do not align with established diagnostic criteria for AIDS.
**Clinical Pearl / High-Yield Fact**
A key point to remember is that a **CD4 count below 200 cells/μL** is a critical threshold for the diagnosis of AIDS, indicating severe immune compromise.
**Correct Answer:** B. CD8 < 500