Human Immunodeficiency Virus (HIV) Quiz

Focused SBA-style practice, followed by the answer and explanation for every question.

Free now: 5 questions
Full bank: 8 questions
Answers: Explained

Free question

Try one with the answer

A question from this quiz. Answer it to see the explanation students get.

In an adult with HIV, which CD4 T-cell count is used to define AIDS?

A CD4 T-cell count less than 400 cells per microlitre
B CD4 T-cell count less than 250 cells per microlitre
C CD4 T-cell count less than 500 cells per microlitre
D CD4 T-cell count less than 350 cells per microlitre
E CD4 T-cell count less than 200 cells per microlitre ✓

The answer is E: CD4 T-cell count less than 200 cells per microlitre

Explanation

Why E is correct

See What is HIV?. Option E is correct. HIV destroys CD4 T cells, the helper lymphocytes (white blood cells) that coordinate the immune response, so the CD4 count is the main measure of how much damage has been done. A normal count is roughly 500 to 2000 cells per microlitre of blood. The count falls in stages: above 500 is stage one and usually causes no symptoms, below 500 brings mild symptoms, below 350 brings more advanced symptoms, and below 200 cells per microlitre is the most advanced stage, which is also called AIDS (acquired immune deficiency syndrome). At this level the immune system is too weak to hold back organisms that are normally harmless, so opportunistic infections appear (such as Pneumocystis pneumonia and candidiasis) along with certain cancers, including Kaposi's sarcoma. In the UK, AIDS is now often called late-stage or advanced HIV, and most people on treatment do not develop it. Antiretroviral treatment allows the CD4 count to recover, which is the aim of care.

Target cells: HIV destroys CD4 T cells, so the CD4 count measures how much damage has been done.
AIDS threshold: a CD4 count below 200 cells per microlitre is the most advanced stage.
Consequence: opportunistic infections and certain cancers appear at this level.

Why the other options are incorrect

A. CD4 T-cell count less than 400 cells per microlitre: A cut-off of 400 cells per microlitre is also too high and would classify many patients with earlier-stage HIV as having AIDS.
B. CD4 T-cell count less than 250 cells per microlitre: A cut-off of 250 cells per microlitre is too high: patients with counts between 200 and 249 do not yet meet the definition of AIDS.
C. CD4 T-cell count less than 500 cells per microlitre: A count below 500 means the count has started to fall and is still mildly affected, often with mild symptoms. It is far from the level that defines AIDS.
D. CD4 T-cell count less than 350 cells per microlitre: A count below 350 marks an earlier stage in which symptoms are becoming more advanced, but it is not the threshold for AIDS. This level is not low enough to define AIDS.

Easy

With Premium, questions you miss become Revision Coach flashcards, scheduled for review.

Question preview

What you will practise

More questions from this set. Start the quiz to answer them and see each explanation.

1
Which statement best describes the appropriate interpretation of a positive point-of-care HIV test?
2
Which stage of the HIV life cycle is directly targeted by integrase inhibitors?

Revise before you test

Review SimpleMed's doctor-written article, then return here to check recall.

Read the topic article

Need wider coverage?

Explore every Infection topic set, or build a tailored mixed session.

Browse subject quizzes