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Infectious Disease

HIV Infection

Chronic retroviral infection targeting CD4 T cells; modern ART enables near-normal lifespan and U=U (undetectable = untransmissible).

Last reviewed 30 Jun 2026 - MedicoMedics editorial team

HIV virion budding from CD4 T cell

Pathophysiology

HIV-1 binds CD4 + CCR5/CXCR4; reverse-transcribes RNA to DNA integrated by integrase; progressive CD4 depletion causes AIDS if untreated.

Sources: DHHS HIV 2024; HPTN 083 (NEJM 2021;385:595)

Presentation

Acute retroviral syndrome (fever, rash, lymphadenopathy). Chronic: opportunistic infections when CD4 <200 (PJP, toxoplasmosis, CMV, MAC).

Diagnosis

4th-gen HIV Ag/Ab immunoassay; confirm with HIV-1/2 differentiation. Monitor CD4, viral load, resistance testing.

Management

Start ART at diagnosis. Preferred: BIC/TAF/FTC or DTG-based regimens. PrEP: TDF/FTC or cabotegravir LA. Screen and prophylax OIs (TMP-SMX for CD4<200). U=U with sustained viral suppression.

Sample USMLE-style MCQs

Try 5 questions on this topic. Practice hundreds more free with a trial.

Question 1

Which is a preferred first-line ART regimen?

Question 2

Which is FDA-approved long-acting injectable PrEP?

Question 3

Prophylaxis for PJP starts when?

Question 4

Which is the most sensitive test for acute HIV?

Question 5

First-line regimen in pregnancy?

References

Primary guidelines and peer-reviewed sources used for this entry. Reviewed 30 Jun 2026 by MedicoMedics editorial team.

  1. DHHS HIV 2024
  2. HPTN 083 (NEJM 2021;385:595)

Frequently asked

U=U?

Undetectable viral load = zero sexual transmission risk.

Long-acting ART?

Cabotegravir + rilpivirine IM monthly/2-monthly (ATLAS-2M).

PJP prophylaxis?

TMP-SMX when CD4 <200 or thrush.

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