Which opportunistic infection is strongly associated with CD4 count below 200?
Appeared in: AIIMS CRE 2025
Explanation
Pneumocystis jirovecii pneumonia (PJP) is the opportunistic infection most strongly and specifically associated with a CD4 count dropping below 200 cells/mm³.
According to clinical guidelines, this threshold is the primary indicator to begin prophylaxis (preventive treatment) against PJP, typically with trimethoprim-sulfamethoxazole.
Data shows that 95% of PJP cases in patients with HIV occur when their CD4 count is below 200, making this a critical and defining marker.
Why Other Options Were Wrong
Option A: The risk for Toxoplasmosis becomes most significant at a lower level of immunosuppression, with prophylaxis typically recommended when the CD4 count falls below 100 cells/mm³.
Option C: Tuberculosis can reactivate or cause a new infection at any CD4 count in a person with HIV. There is no specific CD4 threshold, like 200, that defines the risk for TB.
Option D: Kaposi's sarcoma is a virus-induced cancer, not a classic infection. While it is an AIDS-defining illness, it can appear at various CD4 levels and is not exclusively tied to the 'below 200' threshold.
Related Visual
Visual 1: Chart: A diagram illustrating the progression of HIV and the corresponding CD4 count thresholds for various opportunistic infections (PJP at <200, Toxoplasmosis at <100, MAC at <50).
Clinical Relevance
Nursing practice connection: Knowing CD4 count thresholds for opportunistic infections in HIV/AIDS helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Nurses play a vital role in educating patients about the importance of adhering to antiretroviral therapy (ART) to keep their CD4 count high and prevent opportunistic infections.
Monitoring a patient's CD4 count is a key nursing assessment to anticipate risks, recognize early signs of infection, and ensure timely initiation of prophylaxis.
What if? If a patient's CD4 count dropped to 90 cells/mm³, the nurse should recognize the risk for both PJP and Toxoplasmosis, and ensure the patient is on appropriate prophylaxis, likely trimethoprim-sulfamethoxazole, which covers both.
How to Approach the Question
First, identify the key terms in the question: 'opportunistic infection' and 'CD4 count below 200'.
This is a factual recall question that tests your knowledge of HIV/AIDS management.
Recall the specific CD4 thresholds that trigger prophylaxis for major opportunistic infections.
The 'below 200' mark is the most famous threshold, specifically for initiating prophylaxis against Pneumocystis jirovecii pneumonia (PJP).
Evaluate the other options: Toxoplasmosis is associated with a lower count (<100), while TB and Kaposi's sarcoma are not defined by this specific threshold.
This process of elimination confirms that PJP is the most accurate answer.
Concept Tested & Keywords
Concept Tested: CD4 count thresholds for opportunistic infections in HIV/AIDS.