HIV INFECTION

✓ Medically ReviewedDISEASEID: MDBT0149🚨 TRIAGE: ROUTINEICD-10: B24

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Definition

CLINICAL DEFINITION

HIV infection is chronic retroviral infection (lifelong RNA virus that inserts into DNA). It starts with seroconversion (early antibody phase) with fever, sore throat and rash. Untreated disease depletes CD4 T cells (helper immune cells) over years. AIDS (advanced weak-immunity stage) brings opportunistic infections (germ attacks during weak defence). Daily antiretroviral therapy (virus-suppressing drugs) blocks replication (virus copying) and prevents spread.

IN PLAIN ENGLISH

HIV harms the defence cells of blood. It spreads by sex, blood or birth. At first it acts like flu for weeks. With no drugs it weakens defence for years. Daily drugs keep it asleep and stop spread.

COMMON MISCONCEPTION / WHAT IT DOES NOT MEAN

HIV infection is not AIDS (advanced weak-immunity stage) alone, since many live with controlled virus. It is not a positive screen (first lab check) alone without confirmatory antigen-antibody (combined virus and defence test) plus RNA (virus gene test). It is not immediate severe illness after exposure without seroconversion illness. It is not cured by antibiotics (bacteria drugs) and persists as latency (hidden virus) without therapy.

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Word Breakdown

de- / in-

=de means loss with in meaning into

immun- / fici- / fect-

=immune means defence with fici meaning make and fect meaning invade

-ency / -ion

=condition with process meaning disease state

Literal Meaning: state of entered germ causing defence failure

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Abbreviations

HIV=Human immunodeficiency virus - virus that attacks helper immune cells

AIDS=Acquired immunodeficiency syndrome - advanced HIV with weak immunity

ART=Antiretroviral therapy - drug combination that suppresses virus

CD4=Cluster of differentiation 4 - marker on helper immune cells

VL=Viral load - amount of virus in blood

PrEP=Pre-exposure prophylaxis - medicine taken to prevent infection

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Synonyms & Variants

HIV disease›Human immunodeficiency virus infection›HIV positive›

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Category-Specific Context

HIV infection is a Disease because it is a lasting retroviral process with stages, spread and cure goals. It is not a single Symptom (patient complaint) such as fever alone. It moves from seroconversion to chronic infection to AIDS without therapy. Management centres on early suppression with resistance watch. It needs confidential testing with partner and pregnancy care.

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Clinical Context & Usage

CLINICAL SETTINGS

Sexual Health and HIV ClinicInfectious Diseases Outpatient ServicePrimary Care for HIV ScreeningAntenatal Clinic for Prevention of Vertical SpreadEmergency Department for Seroconversion IllnessNeedle Exchange and Outreach Testing Service

USAGE & DOCUMENTATION NOTES

Use HIV infection for confirmed infection across acute and chronic stages. Specify stage such as acute seroconversion, chronic infection or AIDS with CD4 (helper count) and viral load (virus amount). Do not label every febrile rash as seroconversion without exposure and tests. Record exposure, viral load, CD4, resistance, hepatitis B, syphilis and tuberculosis screen each visit.

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Primary Causes & Pathophysiology

PATHOPHYSIOLOGY

HIV binds CD4 receptors (helper-cell docks) with CCR5 or CXCR4 coreceptors (entry helpers). It infects CD4 T cells (helper cells), macrophages (eater cells) and dendritic cells (alert cells). Reverse transcription (RNA to DNA copying) with integration (viral DNA insertion) creates latency (hidden inactive virus). Ongoing replication (virus copying) depletes helpers and drives activation (chronic immune firing). Weak defence then allows opportunistic growth (weak-immunity germs) and cancers.

PRIMARY CAUSES

HIV-1 infection via sex, blood or birth

Lentivirus (slow retrovirus) depletes CD4 helpers through direct killing and chronic activation

HIV-2 infection mainly in West Africa

Related retrovirus spreads by same routes with slower CD4 decline but similar AIDS risk

Unprotected sexual exposure

Mucosal inoculation (genital lining entry) without condoms allows virus to reach immune cells

Blood exposure via shared needles or transfusion

Direct bloodstream entry bypasses mucosa and seeds rapid systemic spread

Vertical spread in pregnancy, birth or breastfeeding

Maternal viraemia (virus in blood) passes to child without preventive maternal therapy and infant prophylaxis (preventive drugs)

Lack of testing with late presentation

Undiagnosed viraemia sustains transmission while low CD4 allows opportunistic disease before care

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Epidemiology

Prevalence:About 40 million people live with HIV worldwide. Sub-Saharan Africa (region south of the Sahara) carries the highest share. New infections number over one million each year. Key groups such as men who have sex with men and people who inject drugs carry higher risk.

Age Group:All ages can acquire HIV after exposure. Adults aged 15 to 49 years carry highest incidence. Adolescents and young women in high-burden areas face high risk. Children acquire it vertically (mother to child) without prevention.

Geographic Distribution:HIV occurs worldwide in all regions. Highest burden sits in sub-Saharan Africa per WHO reports. Eastern Europe and Central Asia show rising incidence. High-income settings show concentrated spread in key groups. No climate restriction applies because spread is person to person.

Red Flags & Triage ★

TRIAGE LEVEL

🚨 ROUTINE

DO NOT MISS — LIFE-THREATENING PRESENTATIONS

Acute seroconversion with very high infectivity
Opportunistic infection signalling AIDS onset
Tuberculosis coinfection needing joint timing
Cryptococcal meningitis with raised pressure
Pregnancy needing urgent vertical prevention

URGENT EVALUATION TRIGGERS

Fever with neck stiffness or confusion suggesting meningitis
Breathlessness with low oxygen suggesting Pneumocystis disease
Fever with weight loss and CD4 below 200
Rash with low pressure after starting therapy
Positive infant test needing urgent prophylaxis

Contraindications & Precautions

CONTRAINDICATIONS

Do not delay antiretroviral therapy for lack of symptoms because immune harm continues
Do not stop therapy without supervision because rebound (virus return) and resistance follow
Do not use immunosuppressants (immune-weakening drugs) without prophylaxis (preventive drugs) when CD4 is low
Do not advise breastfeeding without local guidance where safe alternatives exist

SPECIAL PRECAUTIONS

Screen for tuberculosis, hepatitis B and syphilis before starting therapy
Monitor kidney, liver and bone health on tenofovir (kidney-affecting drug)
Counsel condoms with needle safety and U equals U (undetectable equals untransmittable)
Watch for immune reconstitution syndrome (recovery inflammation) after starting therapy
Arrange partner testing with antenatal prophylaxis and infant follow-up

Complications

DOWNSTREAM CLINICAL COMPLICATIONS

Pneumocystis pneumonia with breathlessness and low oxygen
Tuberculosis with prolonged cough and wasting
Cryptococcal meningitis (fungal brain-cover infection) with headache
Toxoplasmosis (parasite brain infection) with focal signs
Kaposi sarcoma (vessel tumour) with skin and mouth lesions
Non-Hodgkin lymphoma and cervical cancer
Chronic heart, kidney, liver and bone disease from inflammation

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Confused With (LASA & DDx) ★

LEXICAL (LASA) — SIMILAR NAMES

HPV

Shares acronym style but means wart virus causing cervical disease, not immune deficiency

HBV

Shares sex and blood routes but means liver virus needing vaccine and different drugs

HAV

Shares hepatitis label but means acute food-borne liver virus without chronic immune loss

CLINICAL DIFFERENTIAL DIAGNOSES (DDx)

Infectious mononucleosis from EBV

Key Distinguishing Feature: Positive heterophile screen (glandular fever test) without HIV antigen-antibody and RNA positivity

Cytomegalovirus infection

Key Distinguishing Feature: Positive CMV antibody (recent infection marker) with negative HIV RNA (virus gene test)

Secondary syphilis

Key Distinguishing Feature: Positive treponemal test (syphilis confirmatory test) with palm-sole rash that clears with penicillin

Acute influenza

Key Distinguishing Feature: Positive flu PCR (flu gene test) with short fever course and no seroconversion pattern

Acute hepatitis B

Key Distinguishing Feature: Marked liver enzyme rise with hepatitis surface markers and no HIV RNA

Drug reaction with rash

Key Distinguishing Feature: Recent new drug with eosinophilia (allergy cells) that settles on withdrawal

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Clinical Pearls

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Test fever with rash after exposure using antigen-antibody plus RNA and do not rely on antibodies alone in the window.

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Start antiretroviral therapy fast and do not wait for CD4 fall once diagnosis is confirmed.

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Keep virus undetectable with daily adherence because undetectable equals untransmittable when sustained.

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Screen every new case for tuberculosis, hepatitis B and syphilis and check kidney and liver before tenofovir.

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Offer partner testing with condoms, needle safety, PrEP (preventive pills) and PEP (post-exposure pills) counselling.

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Example Usage & SOAP

CLINICAL SENTENCE

""29-year-old with fever and rash after exposure has acute HIV infection.""

IN A SOAP NOTE

S: 29-year-old man with 1-week fever, sore throat and rash 3 weeks after unprotected sex, no chest pain. O: Temp 38.3C, BP 118/74, HR 96, RR 18, SpO2 98 percent on air, red throat with tender neck nodes and faint trunk rash. A: Likely acute HIV seroconversion needing confirmatory tests. P: HIV antigen-antibody plus RNA with CD4, syphilis and hepatitis screens, counselling with condoms and partner testing, rapid ART referral.

DIFFERENTIAL DIAGNOSIS CONTEXT

Fever with sore throat and rash after exposure favours acute HIV seroconversion over flu. Positive heterophile test (glandular fever screen) favours EBV mononucleosis. Palm-sole rash with positive treponemal test (syphilis confirmatory test) favours secondary syphilis. Short flu-positive course favours influenza. Test HIV antigen-antibody plus RNA with syphilis screen.

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Classifications & Scoring

STAGING SCALE

WHO clinical staging of HIV disease

Stages as 1 to 4 by clinical events from silent to AIDS-defining illness to guide therapy urgency

STAGING SCALE

CDC HIV classification

Stages as A, B and C with CD4 bands where C or low CD4 defines AIDS

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Prognosis

SHORT-TERM OUTCOME

Seroconversion illness usually settles within weeks. Viral load often falls fast once therapy starts. Without therapy short term risk is onward spread and opportunistic illness. Early diagnosis with rapid therapy improves immediate outlook.

LONG-TERM PROGNOSIS

Sustained undetectable virus on therapy brings near-normal life span. Without therapy most progress to AIDS within years. Late presentation with low CD4 worsens survival. Daily adherence (regular pill taking) decides lasting control.

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References & Coding

ICD-10 DIAGNOSTIC CODE

B24

LITERATURE CITATIONS & GUIDELINES

[1]WHO ICD-10 B24 Unspecified HIV disease

[2]WHO Consolidated guidelines on HIV

[3]DHHS Guidelines for antiretroviral agents in adults and adolescents

[4]Harrisons Principles of Internal Medicine retroviral diseases

MEDICAL DISCLAIMER — This content is intended for educational purposes and qualified healthcare professionals only. Always refer to current clinical diagnostic criteria, institutional protocols, and official guidelines. Medobo is not responsible for clinical decisions made based on this content.