Infectious Disease

HIV

A chronic retroviral infection that progressively impairs CD4-mediated immunity, but is now usually controllable with antiretroviral therapy that protects health and prevents sexual transmission when viral suppression is sustained.

In a nutshell

HIV is a chronic retroviral infection that progressively impairs CD4-mediated immunity. It may be asymptomatic or present with seroconversion illness, an indicator condition or opportunistic disease. Confirm testing, start specialist-led ART for everyone, monitor viral suppression and CD4 recovery, and make PEP, PrEP, U=U, pregnancy and opportunistic-infection pathways explicit.

Classic presentation

A non-specific febrile illness with sore throat, rash and lymphadenopathy after a possible exposure, or years later with weight loss, chronic diarrhoea, recurrent infection, tuberculosis, Pneumocystis pneumonia, malignancy or neurological disease.

Key points

A normal examination or preserved CD4 count does not exclude recent or clinically important HIV; test when risk, symptoms or an indicator condition makes it plausible.
Use a laboratory fourth-generation antigen/antibody test and confirm a reactive result; consider HIV RNA with the laboratory if acute infection is strongly suspected despite an early negative screen.
CD4 count estimates immune suppression and opportunistic-infection risk, while viral load measures replication and treatment response.
Offer ART to everyone with confirmed HIV irrespective of CD4 count; the HIV specialist selects the regimen using current BHIVA guidance, resistance, co-infection, organ function, interactions, pregnancy and preference.
Sustained undetectable viral load means no sexual transmission risk (U=U), but it does not remove the need for STI prevention, adherence or follow-up.
Advanced immunosuppression requires infection-specific prophylaxis and rapid assessment for opportunistic infection; ART timing may need specialist adjustment in CNS infection or tuberculosis.
PEP is an emergency after a significant exposure and must be assessed as soon as possible and within 72 hours; PrEP is for ongoing risk before exposure.
Pregnancy, infant feeding, vaccinations, hepatitis and cardiovascular, renal, mental-health and social needs all require coordinated long-term care.

First-line investigation

Laboratory fourth-generation HIV antigen/antibody testing with confirmatory testing when reactive, followed by viral load, CD4 count, resistance and baseline co-infection and safety assessment through the HIV service.

Management

Test and identify emergencies

Offer appropriate HIV testing, confirm reactive results, assess for acute infection or opportunistic disease, and arrange urgent specialist review; assess a possible exposure for PEP within 72 hours.^4,3,10

Stage infection and plan ART

Measure viral load, CD4 count, resistance, organ function and relevant co-infections; start specialist-selected ART promptly for confirmed HIV regardless of CD4 count.^1,5,8

Suppress virus and prevent opportunistic disease

Monitor viral suppression and immune recovery, support adherence and manage infection-specific prophylaxis or active opportunistic disease through the HIV and infectious-disease team.^1,5

Explain U=U and prevention

Explain that sustained undetectable viral load prevents sexual transmission, while continuing STI screening, partner notification, safer-sex support and eligibility assessment for PrEP or PEP.^2,9,10

Coordinate pregnancy and complex care

Use the current BHIVA pregnancy pathway for ART, viral-load monitoring, delivery, infant prophylaxis and feeding; involve specialists early for pregnancy, CNS infection, tuberculosis, severe immunosuppression or major interactions.^6,1,5

Protect long-term health

Review vaccination, hepatitis, renal, cardiovascular, bone, mental-health, substance-use, sexual-health, social and safeguarding needs, using the Green Book and HIV specialist standards.^12,7,1

Exam traps

Do not diagnose HIV from a reactive point-of-care screen alone; confirmation is required.
A negative test soon after exposure may be within the window period; repeat or add specialist RNA testing when acute infection is plausible.
Do not wait for the CD4 count to fall before starting ART.
U=U applies to sexual transmission when viral suppression is sustained; it does not mean HIV is cured or that other STIs cannot be transmitted.
PEP follows a significant exposure and is time-critical; PrEP is planned prevention for ongoing risk.
The timing of ART is not identical for every opportunistic infection, particularly CNS infections and tuberculosis; involve the HIV/infectious-disease team.

Illustrations

CD4 depletion and viral-load trajectoryGraph showing typical viral load and CD4 count trends from primary infection through clinical latency and advanced immunosuppression, with ART suppressing viral load and supporting immune recovery.PassFinals · original

Immune suppression and opportunistic diseaseConcept diagram linking falling CD4-mediated immunity to increasing risk of opportunistic infections and malignancy; it must not imply that a single CD4 threshold diagnoses every infection.PassFinals · original

Oral candidiasisClinical photograph of white plaques of oral candidiasis on the tongue and buccal mucosa, an indicator of immune compromise but not specific for HIV.Photo Credit: Content Providers(s): CDC, Wikimedia Commons · Public domain

Key sources

This page is exam revision material, not medical advice, and must not be used for patient care. Always check drug doses against the BNF and current guidance. Full disclaimer.