HIV

Question 1

Outline the basic virological features of HIV

Answer 1

Retrovirus with surface glycoprotein (gp120) which binds to CD4 glycoprotein, most importantly on host T-helper cells.
It destroys these cells and allows HIV to progress.

There are two HIV strains (1 and 2)
- 1 (group M) is most common

Question 2

What is a normal CD4 lymphocyte count and what levels are relevant in HIV?

Answer 2

Normal count is 500-1500 cells/mm3

Antivirals should be commenced if/when <350

HIV often asymptomatic until <200 cells/mm3 - most AIDS diagnoses at this level
- also start pneumocystis jirovecci pneumonia prophylaxis at this point

Question 3

Describe the modes of transmission and epidemiology of HIV infection (including high risk groups)

Answer 3

Blood/body fluid spread
Sex
Blood - IVDU, unscreened blood, mother>foetus

High risk groups

• Homo/bisexual
• IVDUs
• those who have sex with people from high-risk areas (80% of heterosexual patients infected abroad)
• recipients of unscreened blood products
• any child of infected mother

90% of those infected live in developing world

Question 4

Describe the clinical presentation of acute HIV infection

Answer 4

Usually 2-4 weeks post-exposure > seroconversion illness (in 30-60% of individuals)
Similar to glandular fever/flu
- fever
- rash
- pharyngitis
- lymphadenopathy

Other possible symptoms

• diarrhoea
• meningitis
• neuropathy

This timeframe will be antibody negative (up to 3 months), but antigen positive and viral load can still be detected

Question 5

After recovery from seroconversion illness, what symptoms may a person present with indicating an underlying HIV infection? (not including specific opportunistic infections)

Answer 5

Weight loss
Lymphadenopathy
Night sweats
Fever, lethargy/malaise
Oral ulcers
Recurrent/persistent warts, general skin problems
Recurrent diarrhoeal infections

Question 6

What are some opportunistic infections in HIV? (not including AIDS-defining illnesses)

Answer 6

Thrush
Skin changes
Cryptosporidiosis
Mycobacterium Avium Complex
Aspergillosis/Bacterial Pneumonia

Question 7

What are some of the AIDS-defining illnesses?

Answer 7

TB, pneumocystis (PCP)
Cerebral Toxoplasmosis
Cryptococcal meningitis
Kaposi's sarcoma
Non-Hodgkin's lymphoma
CMV
HSV - persistent ulcer or respiratory infection
Cervical cancer
Persistent crytosporidiosis
Recurrent opportunistic infections (e.g. pneumonia, septicaemia)

Question 8

List the laboratory tests used for INITIAL DIAGNOSIS of HIV infection

Answer 8

Combined test for HIV antigen and HIV antibody (ELISA)

After exposure, this test can take up to three
months to become positive, and an individual
becomes highly infectious prior to positive testing (high viral load due to no antibody development)

Question 9

Describe laboratory and clinical monitoring of HIV disease, and why they are done

Answer 9

HIV Viral Load (PCR) - main use of HIV viral load is to monitor the effectiveness of anti-retroviral therapy
HIV Resistance Testing - patients become resistant to treatments
CD4 count

Avidity testing
Subtype determination
Tropism testing
Drug levels

Question 10

Describe the treatment regime (not including drug types) of HIV infection (not including the opportunistic infections), what the target viral load is, and when to start/change treatments

Answer 10

Combined Antiretrovirals

• at least three from at least two different groups
• adherence >95% required

Encourage start at CD4 <350, or ASAP <200
- before third trimester in pregnancy

Target viral load <40 copies/mL

Adjust if viral load not suppressed after 4-6 weeks

• also adjust if lipodystrophy occurs
• adjust to (ideally) three new drugs if resistance develops

Question 11

Describe some classes of HIV treatments, and possible adverse effects

Answer 11

Nucleoside reverse transcriptase inhibitors

• zidovudine
• marrow toxicity, neuropathy, lipodystrophy

Non-nucleoside reverse transcriptase inhibitors

• efavirenz
• skin rashes, hypersensitivity, drug interactions

Protease inhibitors
- drug interactions, diarrhoea, lipodystrophy and hyperlipidaemia

Integrase inhibitors

• raltegravir
• rashes

Chemokine Receptor Antagonists
Fusion inhibitors

Question 12

How may HIV infections be prevented?

Answer 12

Behaviour change and condoms
Circumcision
Treatment as prevention - VL undetectable = untransmissable (pregnancy)
Pre-exposure prophylaxis (PrEP)
Post-exposure prophylaxis for sexual exposure (PEPSE)

Question 13

List the infections which may be transmitted by needlestick injuries, and the probability of this happening

Answer 13

Hepatitis B - exposure to surface antigen positive blood up to 30% (1:3)

Hepatitis C - exposure to RNA positive blood ~3% (1:30)

HIV - exposure to positive blood ~0.3% (1:300)

• Mucocutaneous exposure to HIV (blood/body fluid splashes into eyes/nose/mouth or broken skin) <0.1% (1:1000)

Question 14

Outline the recommended procedure following a needlestick injury/possible exposure, and how to assess risk

Answer 14

First aid

• wash off splashes on skin with soap and running water
• encourage bleeding if skin has been broken (do not suck)
• wash out splashes in the eye, nose, mouth
• assess risk (by someone other than victim)
• REPORT to senior manager or doctor AND to OHS

The risk is assessed by considering

• source of contamination
• extent of injury and the type of sharp (if any) causing it
• likelihood of B/C/HIV in the source
• Hep B vaccination history

Ideally test source with informed consent
HIV exposure is an emergency
- prophylaxis can prevent infection by up to 80%, should be administered within one hour, but still worthwhile up to 72 hours

Question 15

Which body fluids should be considered the same risk as blood?

Answer 15

• CSF
• pleural/peritoneal/pericardial fluid
• breast milk
• amniotic fluid
• vaginal secretions, semen
• synovial fluid
• any other body fluid containing visible blood
• unfixed tissues and organs
• saliva - dental procedures
• exudate/tissue fluid from burns or skin lesions