ID: HIV, viral hepatitis and blood-borne viruses

• HIV: HIV Basics | Testing for HIV | Primary HIV Infection | Indicator Conditions — When to Think of HIV | Opportunistic Infections and Cancers | Antiretroviral Therapy | Drug Interactions in HIV | Starting ART and IRIS | Preventing HIV — PrEP, PEP and U=U | HIV in Pregnancy
• Viral hepatitis: Viral Hepatitis at a Glance | Hepatitis A | Hepatitis B | Hepatitis B Serology | Treating and Preventing Hepatitis B | Hepatitis D | Hepatitis C | Hepatitis E
• Blood-borne viruses in practice: Who to Screen for Blood-borne Viruses | After an Exposure
• Revision: Drug Reference Table | Spot the Diagnosis | Exam-style Scenarios | Key Points | Guidelines and Further Reading

🧬 HIV, viral hepatitis and blood-borne viruses — page 3 of the Infectious Diseases chapter. HIV is now a long-term condition: with early diagnosis and treatment, people with HIV have a near-normal life expectancy and cannot pass it on sexually when their viral load is undetectable. Hepatitis C is curable with 8–12 weeks of tablets, and hepatitis B is preventable by vaccination and controllable with treatment. The biggest problem is late diagnosis — so offer tests widely.
Your four questions for every patient: Should this person be tested for HIV, hepatitis B and hepatitis C? If positive, how advanced is the infection (CD4, viral load, liver fibrosis)? What treatment do they need, and what will it interact with? How do we protect partners, babies and contacts?

HIV Basics

• HIV (human immunodeficiency virus) — a retrovirus that infects CD4 T cells, copies its RNA into DNA (reverse transcriptase) and inserts it into the cell's DNA (integrase). Without treatment, CD4 cells fall over years → AIDS.
• Transmission — sex (anal sex carries the highest sexual risk), sharing injecting equipment, mother to baby (pregnancy, birth, breastfeeding), contaminated blood and needlestick injuries. Not spread by kissing, sharing utensils or everyday contact.
• Natural history without treatment:
  • Primary infection (2–6 weeks after exposure) — flu-like or glandular fever-like illness in many; very high viral load (highly infectious).
  • Chronic phase (often years with few symptoms) — gradual CD4 loss; minor conditions (shingles, seborrhoeic dermatitis, oral thrush).
  • AIDS — CD4 under 200 cells/microlitre or an AIDS-defining illness (opportunistic infections, certain cancers).
• Two key blood tests:
  • CD4 count (normal about 500–1,500 cells/microlitre) — shows immune damage and the risk of opportunistic infections.
  • Viral load (HIV RNA copies/mL) — shows how active the virus is and whether treatment is working (target — undetectable, under 50 copies/mL).
• UK picture — most people with HIV are diagnosed and on effective treatment, but a large proportion are still diagnosed late (CD4 under 350), which carries higher risk of illness and death.
• Living with HIV — with treatment, life expectancy is close to normal; long-term issues include cardiovascular disease, kidney and bone health, mental health, stigma and ageing.

Testing for HIV

• Any doctor can offer an HIV test — verbal consent is enough; no specialist counselling is needed (explain the benefits and how results will be given).
• Who to test (BHIVA/BASHH and NICE NG60):
  • Anyone with an indicator condition or symptoms suggesting HIV (see below).
  • Everyone attending sexual health and drug services, all pregnant women, people with TB, hepatitis B or C, or lymphoma.
  • Higher-risk groups — men who have sex with men, people from countries with high HIV prevalence, people who inject drugs, sex workers, sexual partners of people with HIV.
  • In areas of high HIV prevalence — routine ("opt-out") testing for all adults having blood tests in emergency departments, on hospital admission and at GP registration.
• Tests:
  • Fourth-generation test (HIV antibody plus p24 antigen) — the standard lab test; detects most infections by 4 weeks after exposure; a negative result 45 days after the last exposure excludes HIV.
  • Point-of-care and self-tests (antibody-based) — longer window period (up to about 90 days); confirm positives in the lab.
  • HIV viral load — very high in primary infection; used for monitoring, not usually for screening.
• Giving a positive result — face to face where possible, with prompt referral (within 2 weeks — sooner if unwell) to an HIV service; partner notification (through the HIV or sexual health team); reassure about treatment and outlook.
• Missed opportunities — many people diagnosed late had seen healthcare professionals with indicator conditions in the years before; if in doubt, offer a test.

Primary HIV Infection

• Timing — 2–6 weeks after exposure; symptoms in most (though often mild or missed).
• Features — fever, sore throat, maculopapular rash (trunk), mouth ulcers, lymphadenopathy, muscle and joint pain, headache, diarrhoea; sometimes aseptic meningitis, Guillain–Barré syndrome or facial palsy.
• Blood tests — lymphopenia (or atypical lymphocytes), low platelets, raised liver enzymes.
• "Glandular fever-like illness" — always consider primary HIV (and test) in someone with a negative EBV test, a rash or mouth ulcers, or recent risk.
• Testing — a fourth-generation test may be negative very early; the viral load is very high — test both and repeat if suspicion remains.
• Why it matters — people are most infectious at this stage; starting ART early protects the immune system and partners.

Indicator Conditions — When to Think of HIV

Opportunistic Infections and Cancers

• Prophylaxis — co-trimoxazole when CD4 is under 200 (prevents PCP and toxoplasmosis) until CD4 recovers on ART; screen for latent TB and cryptococcal antigen (CD4 under 100) in at-risk patients.
• Vaccines — pneumococcal, influenza, hepatitis A and B, HPV, COVID-19, shingles (non-live); avoid live vaccines (e.g. yellow fever, MMR) when CD4 is under 200.

Antiretroviral Therapy

• Offer ART to everyone with HIV, whatever the CD4 count, as soon as possible (often the same week as diagnosis) — benefits the person and stops transmission.
• Usual regimen — three drugs: two nucleoside reverse transcriptase inhibitors (NRTIs) plus an integrase inhibitor; often a single daily tablet. Two-drug regimens (dolutegravir plus lamivudine) are used in selected people (no hepatitis B, no resistance). Long-acting injections (cabotegravir plus rilpivirine every 2 months) are an option for people already suppressed.

• Monitoring — viral load (should become undetectable within about 3–6 months, then checked every 6–12 months), CD4 count, kidney function and urine protein, liver tests, lipids, bone health and cardiovascular risk; resistance testing before starting and if treatment fails.
• Adherence is essential — missed doses allow resistance; support mental health, housing, drug and alcohol problems, and stigma.
• Never stop ART in hospital without HIV team advice — if the patient can't take oral medicines, contact the HIV team or pharmacy (liquid forms, NG options).

Drug Interactions in HIV

• Always check before prescribing anything to someone on ART — use the Liverpool HIV drug interaction checker (including over-the-counter, herbal and recreational drugs).
• Boosted regimens (ritonavir or cobicistat) — strong CYP3A4 inhibition:
  • Simvastatin — contraindicated (rhabdomyolysis); use low-dose atorvastatin, rosuvastatin or pravastatin with advice.
  • Inhaled and nasal fluticasone and budesonide, and steroid joint injections (triamcinolone) — Cushing's syndrome and adrenal suppression; use beclometasone or alternatives.
  • Amiodarone, some DOACs, oral midazolam, sildenafil (raised levels), ergot drugs, some antipsychotics and antiseizure drugs, colchicine.
• Enzyme inducers lower ART levels (treatment failure and resistance) — rifampicin (TB — needs specialist regimen changes), carbamazepine, phenytoin, St John's wort.
• Absorption — PPIs and H2 blockers reduce rilpivirine (and atazanavir); antacids, calcium, iron and magnesium reduce integrase inhibitor absorption.
• Contraception — some ART reduces hormonal contraceptive effect (efavirenz, boosted regimens) — check; levonorgestrel emergency contraception needs a double dose with enzyme inducers (or use a copper IUD).
• Recreational drugs — boosters raise levels of MDMA, ketamine, GHB and some opioids (dangerous toxicity).

Starting ART and IRIS

• Immune reconstitution inflammatory syndrome (IRIS) — as the immune system recovers on ART, it attacks infections that were present, causing a paradoxical worsening (fever, enlarging lymph nodes, worsening chest or brain lesions) usually in the first weeks to months.
• Most common with TB, cryptococcal meningitis, MAC, CMV and PML; higher risk with very low CD4.
• Timing of ART with opportunistic infections:
  • Most OIs (e.g. PCP) — start ART within about 2 weeks.
  • TB — start within 2 weeks if CD4 is under 50, otherwise within about 8 weeks; TB meningitis — specialist decision (higher risk).
  • Cryptococcal meningitis — delay ART for about 4–6 weeks (early ART increases deaths).
• Management of IRIS — exclude new infection, drug reaction and treatment failure; usually continue ART; NSAIDs or steroids for significant IRIS (e.g. TB-IRIS).

Preventing HIV — PrEP, PEP and U=U

• U=U (Undetectable = Untransmittable) — a person with HIV on ART with a viral load that has been undetectable for at least 6 months cannot pass HIV on through sex. This is one of the most powerful messages for reducing stigma and transmission.
• Pre-exposure prophylaxis (PrEP) — HIV-negative people at risk take tenofovir disoproxil–emtricitabine:
  • Daily, or "event-based" dosing (for anal sex between men only).
  • Free through NHS sexual health clinics; requires a negative HIV test, kidney function monitoring, hepatitis B status and regular STI testing.
  • Very effective when taken correctly; doesn't protect against other STIs.
• Post-exposure prophylaxis (PEP) after sexual or occupational exposure to HIV:
  • Start as soon as possible — ideally within 24 hours, and no later than 72 hours; continue for 28 days.
  • Usual regimen — tenofovir disoproxil–emtricitabine plus an integrase inhibitor (e.g. raltegravir).
  • Not usually needed if the source has HIV with an undetectable viral load (for sexual exposure).
  • Available from sexual health clinics and emergency departments; follow-up HIV testing.
• Other prevention — condoms, needle and syringe programmes, opioid substitution therapy, testing and treating partners, antenatal screening.

HIV in Pregnancy

• All pregnant women are offered HIV testing (and hepatitis B and syphilis screening) at booking; repeat testing later in pregnancy if at continued risk.
• ART throughout pregnancy — continue effective regimens; start as soon as possible if newly diagnosed (dolutegravir-based regimens are recommended).
• Delivery — planned vaginal birth if the viral load is under 50 copies/mL at 36 weeks; caesarean section is recommended if the viral load is high (e.g. over 400 copies/mL); IV zidovudine during labour in some situations.
• Baby — antiretroviral post-exposure prophylaxis for 2–4 weeks; HIV testing over the first months (PCR — maternal antibodies cross the placenta).
• Infant feeding — formula feeding removes the risk of transmission and is advised in the UK; women with a sustained undetectable viral load who choose to breastfeed should be supported with close monitoring (BHIVA).
• With good care, the transmission rate in the UK is under 0.3%.

Viral Hepatitis at a Glance

• Acute hepatitis features — tiredness, nausea, loss of appetite, right upper quadrant discomfort, then jaundice, dark urine and pale stools; ALT often in the thousands; many infections (especially in children, and hepatitis C) cause no symptoms.
• Acute liver failure warning signs — rising INR, confusion (encephalopathy), hypoglycaemia — discuss urgently with a liver unit.
• Other causes of hepatitis to consider — EBV, CMV, HSV (severe in pregnancy and immunosuppression), drugs (paracetamol), alcohol, autoimmune hepatitis, ischaemia, Wilson's disease.

Hepatitis A

• Spread — faecal–oral: contaminated food and water, shellfish, travel to areas where it is common, outbreaks among men who have sex with men and people who inject drugs, household contacts.
• Illness — usually mild in children (often no symptoms); adults often have jaundice for several weeks; more severe in older people and those with chronic liver disease; never becomes chronic; lifelong immunity after infection.
• Diagnosis — hepatitis A IgM antibody.
• Management — supportive; avoid alcohol and liver-toxic drugs; monitor INR; notify; exclude from work or school for 7 days after the onset of jaundice (or symptoms); good hand hygiene.
• Prevention — vaccination for travellers, men who have sex with men, people who inject drugs, people with chronic liver disease, haemophilia, some occupations; post-exposure vaccine for contacts within 14 days (with immunoglobulin for some higher-risk contacts — UKHSA).

Hepatitis B

• Spread — mother to baby (the main route worldwide), sex, blood (injecting, needlestick, medical procedures abroad, tattoos), household contact (shared razors and toothbrushes); highly infectious (much more than HIV).
• Who is at risk — people born in countries with high prevalence (Asia, Africa, Eastern Europe), people who inject drugs, men who have sex with men, sex workers, household and sexual contacts of people with hepatitis B, people on dialysis, prisoners.
• Acute infection — often no symptoms, or acute hepatitis with jaundice; rarely acute liver failure.
• Chronic infection (HBsAg positive for over 6 months) — risk depends on age at infection: about 90% of infected newborns but under 5% of infected adults develop chronic hepatitis B.
• Phases of chronic infection (vary over time):
  • HBeAg-positive chronic infection — very high viral load, normal ALT, little liver damage (often young people infected at birth).
  • HBeAg-positive chronic hepatitis — high viral load, raised ALT, active liver damage.
  • HBeAg-negative chronic infection ("inactive carrier") — low viral load, normal ALT.
  • HBeAg-negative chronic hepatitis — fluctuating viral load and ALT, progressive damage.
• Complications — cirrhosis, hepatocellular carcinoma (can occur without cirrhosis — surveillance with 6-monthly ultrasound in cirrhosis and some high-risk groups), extrahepatic disease (polyarteritis nodosa, membranous glomerulonephritis).
• Reactivation — hepatitis B can flare (sometimes fatally) when people are given chemotherapy, rituximab and other B-cell drugs, high-dose steroids, biologics, JAK inhibitors, or hepatitis C treatment — test HBsAg and anti-HBc before these treatments.

Hepatitis B Serology

Treating and Preventing Hepatitis B

• Everyone with chronic hepatitis B needs specialist assessment — viral load, ALT, HBeAg, fibrosis assessment (FibroScan), HCC risk, and testing for hepatitis D, hepatitis C and HIV; vaccinate against hepatitis A.
• Treatment (NICE CG165, EASL) — for active hepatitis or significant fibrosis, cirrhosis, family history of HCC, and other situations:
  • Tenofovir (disoproxil or alafenamide) or entecavir — oral, usually long-term; suppress the virus and reduce cirrhosis and cancer risk; rarely clear HBsAg; stopping can cause severe flares.
  • Peginterferon alfa — a fixed course of injections for selected patients (flu-like symptoms, depression, low blood counts, thyroid problems).
• Prophylaxis before immunosuppression — antiviral (e.g. entecavir or tenofovir) if HBsAg positive, or anti-HBc positive before rituximab and similar high-risk treatments, continued for months afterwards.
• Vaccination:
  • Routine infant vaccination in the UK (part of the 6-in-1 vaccine).
  • At-risk adults — healthcare workers (check anti-HBs after the course), people who inject drugs, men who have sex with men, sex workers, household and sexual contacts, dialysis patients, chronic liver and kidney disease, prisoners, some travellers.
  • Post-exposure — accelerated vaccine course ± hepatitis B immunoglobulin (HBIG) depending on source and recipient status.
• Pregnancy:
  • All pregnant women are screened; women with high viral loads are offered tenofovir in the third trimester to reduce transmission.
  • Babies of HBsAg-positive mothers — hepatitis B vaccine within 24 hours of birth (plus HBIG if the mother is highly infectious), further doses at 4, 8, 12 weeks and 1 year, and a blood test at 12 months to confirm protection.
  • Breastfeeding is safe when the baby is vaccinated.

Hepatitis D

• Hepatitis D (delta) — a defective virus that can only infect people who also have hepatitis B (it needs HBsAg).
• Co-infection (B and D at the same time) — more severe acute hepatitis; superinfection (D on top of chronic B) — the most severe form of chronic viral hepatitis, with rapid progression to cirrhosis.
• Higher prevalence — Eastern Europe, Mediterranean, Central Asia, parts of Africa, people who inject drugs.
• Test all HBsAg-positive people for anti-HDV antibody (and HDV RNA if positive).
• Treatment — specialist: bulevirtide (blocks viral entry into liver cells), peginterferon; prevention — hepatitis B vaccination.

Hepatitis C

• Spread — mainly blood: injecting drug use (most UK infections), blood transfusion before 1991, medical and dental treatment and tattoos in countries with poor infection control; sexual spread mainly among men who have sex with men (especially with HIV); mother to baby (about 5%).
• Natural history — acute infection is usually silent; about 75% become chronic; cirrhosis in about 20–30% over 20–30 years (faster with alcohol, HIV, obesity, older age), then liver cancer and liver failure.
• Extrahepatic problems — cryoglobulinaemia (vasculitic rash, neuropathy, kidney disease), membranoproliferative glomerulonephritis, porphyria cutanea tarda, lichen planus, type 2 diabetes, B-cell lymphoma, fatigue and depression.
• Testing:
  • HCV antibody — shows exposure at some time (stays positive after cure or spontaneous clearance).
  • HCV RNA (PCR) — confirms current infection; used to test for re-infection after cure (no lasting immunity).
  • Many labs now test RNA automatically on antibody-positive samples ("reflex testing"); dried blood spot tests are used in drug services.
• Treatment — direct-acting antivirals (DAAs) for everyone with current infection:
  • Pangenotypic tablets for 8–12 weeks (e.g. sofosbuvir–velpatasvir, glecaprevir–pibrentasvir) — over 95% cure with few side effects.
  • Cure = undetectable HCV RNA 12 weeks after finishing (sustained virological response, SVR12).
  • Interactions — sofosbuvir with amiodarone (severe bradycardia — avoid), PPIs and antacids (reduce some DAAs), enzyme inducers (carbamazepine, phenytoin, rifampicin, St John's wort — contraindicated), statins, ethinylestradiol with some regimens (liver enzyme rises) — check the Liverpool hepatitis interaction checker.
  • Check hepatitis B status first (reactivation during treatment).
• After cure — people with cirrhosis still need 6-monthly HCC surveillance; continue harm reduction (needle exchange, opioid substitution) and retest RNA if at ongoing risk (re-infection).
• No vaccine — prevention is harm reduction, safe medical practice and testing; the NHS aims to eliminate hepatitis C as a public health threat.

Hepatitis E

• Genotype 3 (the UK and Europe) — from undercooked pork (sausages, pork liver), game and shellfish; often silent, or mild hepatitis in older men.
  • Neurological complications — Guillain–Barré syndrome, neuralgic amyotrophy (severe shoulder pain then weakness).
  • Chronic infection in immunosuppressed people (transplant recipients, chemotherapy, HIV) — progressive liver fibrosis; treat by reducing immunosuppression and with ribavirin.
• Genotypes 1 and 2 (South Asia, Africa — contaminated water) — outbreaks; severe in pregnancy (acute liver failure, high maternal mortality in the third trimester).
• Diagnosis — HEV IgM and HEV RNA (PCR — essential in immunosuppressed people, who may not make antibodies).
• Prevention — cook pork thoroughly; blood donations in the UK are screened for HEV.
• Test for hepatitis E in unexplained hepatitis, including suspected drug-induced liver injury (it is often missed).

Who to Screen for Blood-borne Viruses

• Test for HIV, hepatitis B and hepatitis C together in:
  • People who inject or have injected drugs (and their partners).
  • People born or brought up in countries with high prevalence; migrants (NICE PH43).
  • Men who have sex with men; sex workers; people in prison.
  • People with an STI, unexplained abnormal liver tests, or other indicator conditions.
  • Sexual and household contacts of people with hepatitis B; babies of mothers with hepatitis B or C or HIV.
  • Recipients of blood transfusions before 1991 (hepatitis C) and medical care in high-prevalence countries.
• Routine settings — antenatal screening (HIV, hepatitis B, syphilis), blood and organ donors, dialysis and transplant patients, before chemotherapy, rituximab and biologics (hepatitis B and C, HIV), and opt-out testing in emergency departments in high-prevalence areas.
• Healthcare workers — hepatitis B vaccination and response testing; workers doing exposure-prone procedures need clearance for HIV, hepatitis B and C (UKHSA).

After an Exposure

• Immediate first aid — encourage bleeding, wash with soap and running water (don't scrub), irrigate eyes and mouth with water; report to occupational health or the emergency department straight away.
• Source testing — with the source patient's consent (tested by someone other than the exposed worker).
• Sexual exposures — PEP through sexual health services or the emergency department; also offer STI testing and emergency contraception.

Drug Reference Table