HIV

Question 1

first identified in the

Answer 1

early 1980s

Question 2

why if the incidence (new cases) of HIV is decreasing is the, prevalence (total cases) of HIV is increasing

Answer 2

as life expectancy with disease increases.

Question 3

HIV specifically affects

Answer 3

CD4 cells (via CD4 receptors) - replicates and destroys cells

Question 4

extent of HIV is estimated by

Answer 4

patients CD4 T cell count

Question 5

stage 1

Answer 5

corresponds to a ‘normal’ CD4 count >500 cells/μL and the patient is usually asymptomatic;

Question 6

Stage II

Answer 6

is when the count <500 cells/μL and the patient starts to show mild symptoms;

Question 7

Stage III

Answer 7

is described as a CD4 count <350 cells/μL and symptoms start to become more advanced;

Question 8

Stage IV

Answer 8

is when the CD4 count <200 cells/μL and the presentation is more severe, also defined as AIDS.

Question 9

clinical stages

Answer 9

seroconversion

latent stage

AIDs

Question 10

serconversion

Answer 10

this stage is characterised by acute HIV syndrome with symptoms: - fever - malaise - weight loss - generalised rash. This is seen on the image below where the CD4+ count initially drops on initial infection and copies of the HIV virus spike in number.

Question 11

Latent stage

Answer 11

• CD4+ numbers slowly drop, and viral load slowly increases but the disease is clinically silent. HIV associated infections may begin to develop in the late stages.

Question 12

AIDS

Answer 12

• when CD4+ count drops below 200 cells/μL and opportunistic infections begin to take hold.

Question 13

AIDS is the

Answer 13

o Most advanced stage of HIV infection where patient has become immunodeficient

Question 14

AIDS patients are susceptible to

Answer 14

opportunistic infections:  Pneumocystis pneumonioa  Candidiasis  Protozal infections

Question 15

Patient risk factors

Answer 15

• Anyone
• IV drug abusers
• Unprotected sex
• Having another STI

Question 16

HIV pathogen is a

Answer 16

retrovirus

(ssRNA –> DNA –> ssRNA)

• Infects cells with CD4 surface receptors (T helper lymphocytes)
• HIV replicates inside cells

Question 17

Life cycle of HIV

Answer 17

1. Free virus
2. Binding and fusion- virus binds to a CD4 molecule and one of two coreceptors (either CCR5 or CXCR4). Virus fuses with cell
3. Infections- virus penetrates cells and empties content into cell
4. Reverse transcription- ss strands of viral RNA are converted into dsDNA by reverse transcriptase enzyme
5. Integration- viral DNA is combined with the cells own DNA by the integrase enzyme
6. Transcription- when the infected cells divide, the viral DNA is read and long chain of proteins are made
7. Assembly- sets of viral protein chains come together
8. Budding- immature virus pushes out of the cell, taking some membrane with it
9. Immature virus breaks free of the infected cell
10. Maturation- protein chains in the new viral particles are cut by the protease enzymes in to individuals proteins that combe to make a working virus

Question 18

patient symptoms

Answer 18

• Flu-like symptoms
• Oral candidiasis
• Liver and spleen enlargement
• Nausea and vomiting
• Rash

Question 19

Acute HIV infection main symptoms

Answer 19

• central malais
• systmeic fever
• weight loss
• pharyngitis
• mouth sores
• thrush
• myalgia
• rash
• liver and spleen enlargment
• nausea and vomiting

Question 20

main symptoms of AIDS

Answer 20

• Encephalitis
• meningitis
• retinitis
• pneumocystisi pneumonia
• TB
• Tumors
• esophagitis
• chronic diarrhea

Question 21

mode of tranmission

Answer 21

Sexual contact is one mode of transmission - but not the only one.

Any contact of infected bodily fluids with mucosal tissue, blood or broken skin can be a route of transmission. Therefore, apart from sexual contact (that accounts for 95% of infections), HIV can also be transmitted through medical procedures such as blood transfusions, contaminated needles (mainly through needle exchange among IV drug users), or perinatal transmission(vertical transmission).

Question 22

treatment is

Answer 22

not curative but will increase life expectancy

Question 23

The earlier HIV is diagnosed, the better

Answer 23

the prognosis as the higher the CD4+ count can be maintained

Question 24

types of tests

Answer 24

rapid test

serology

PCR

Question 25

Rapid test (Point of care test)

Answer 25

Low cost Rapid that can be done at hone as a discreet postal test Involves either blood testing through a finger prick or saliva Very few false negatives Does produce false positives- need to be confirmed with serology testing

Question 26

Serology

Answer 26

* Involves a full blood sample sent off to a lab with much slower results (7-10 days) * Looks for HIV antigen and HIV antibody * More accurate but might result in a false negative result

Question 27

PCR

Answer 27

Detects HIV nucleic acid Highly sensitive test which can detect very early infection Expensive Results can take up to a week Not used for initial HIV testing but for follow-up and monitoring treatment response

Question 28

Who should be tested?

Answer 28

* Everyone in a population with an incidence rate \> 2/1000 * Bacterial pneumonia/TB [Resp] * Meningitis/dementia [Neuro] * Severe psoriasis; recurrent/multidermal shingles [Derm] * Chronic diarrhoea/weight loss with unknown cause [Gastro] * Any unexplained blood abnormality [Haem] * Lymphoma, anal cancer [Onc] * Cervical intraepithelial neoplasia (CIN) [Gynae] * Any STI/HepB/HepC

Question 29

treatment for HIV

Answer 29

a combined therapy ## Footnote Patients are prescribe a combination of 3 anti-retrovirals (ARVs) (triple blood therapy)

Question 30

PEP stands for

Answer 30

post-exposure prophylaxis

Question 31

post-exposure prophylaxis

Answer 31

Early initiation of ARVs reduces dissemination and replication of HIV in tissue and bodily fluids * Evidence limited (animal studies/ observational) * Assess risk * Give x 3 ARVs for 28 days * Start ASAP (max up to 72 hours) * HIV test at baseline, 1 month and 3 months

Question 32

Ethical dilemmas

Answer 32

* Testing should be done with consent from the patient who should be then trusted to disclose their status with their partner (s) * However, in some situations we might asked not to tell a patients partner * Ethical dilemma rests on patient confidentiality vs harm to the general public * Advised to make sure to talk to the patient through the importance of the disclosure of such info

Question 33

Outcome of infection

Answer 33

* No cure * Chronic infection +/- disability * Death- AIDS * If diagnosed late and untreated * Other infection will kill you