infection - blood borne viruses (HIV)

Question 1

what are presenting complications of HIV?

Answer 1

(complications with fungus - yeast / mould)
oral candidiasis
kaposis’s sarcoma
PCP
(outcome: cure –> chronic infection –> death)

Question 2

what is HIV?

Answer 2

RETROVIRUS
infects & replicates in immune system (CD4 T cells) - destroys the cell
spreads to / infects more cells

Question 3

how does HIV infect a cell?

Answer 3

1. bind with CD4 cell surface receptors, the CD4 then fuse with host cell (HIV enters as well)
2. viral contents emptied into cell
3. reverse transcriptase (ss viral RNA converted to dsDNA by reverse transcriptase)
4. integration: viral DNA combined with cell’s own DNA - via integrase enzyme
5. transcription: infected cell divides, proteins of the viral DNA made
6. assembly: sets of viral protein chains come together
7. budding: immature virus pushes out of the cell, taking some cell membrane with it
8. immature virus breaks free of infected cell (infect other cells)
9. maturation: protein chains in the new viral particle cut by PROTEASE enzyme into individual proteins that combine to make working virus

Question 4

describe the infection of HIV virus (viral load) against the CD4 count:

Answer 4

1. acute infection / seroconversion (initial infection): CD4 count slight decrease, infection load v high
2. latent infection: own immune system try to mount up an immune response (short drop in HIV), slight rise in CD4 (short lasting & not very effective)
3. symptomatic infection: up to 20/30 years, CD4 decrease until symptoms appear (CD4 < 500) e.g. PCP, skin infections, cold sores, oral candidiasis
4. severe infection / AIDS: CD4 < 200
   (ALSS)

Question 5

what are the different stages of HIV infection and CD4 count?

Answer 5

stage I: asymptomatic, CD4 > 500
II: mild, CD4 < 500
III: advanced, CD4 <350
IV (AIDS): severe, CD4 < 200

Question 6

what are the main symptoms of acute HIV infection?

Answer 6

systemic: fever, weight loss
central: malaise, headache
mouth: sores, thrush
muscles: myalgia
hepatosplenomegaly (like malaria)
skin rash
gastric: vomiting, nausea
lymphadenopathy - drains into lymph

Question 7

which cancer is linked to HIV?

Answer 7

Kaposi’s sarcoma:
a cancer that causes patches of abnormal tissue to grow under the skin, in the lining of the mouth, nose, and throat, in lymph nodes, or in other organs. These patches, or lesions, are usually red or purple. They are made of cancer cells, blood vessels, and blood cells

Question 8

what are HIV associated conditions?

Answer 8

CVS: heart disease, stroke
liver: hep C
brain: meningitis
mouth & throat: cold sores & ulcers, candida (thrush)
blood: hyperglycaemia, dyslipidaemia
lungs: PCP, TB, histoplasmosis
bone: osteoporosis
body: HIV wasting syndrome
repro: genital ulcers, HPV, candida, menstrual problems

Question 9

how is HIV transmitted?

Answer 9

1. sexual: vaginal, anal, oral
2. sharing injecting equipment
3. vertical: in utero, childhood / breast feeding
4. medical procedures: blood / blood-products, skin grafts, organ donation

Question 10

what are the factors affecting HIV transmission?

Answer 10

type of exposure
viral level
other STI present: local effects, effects on immune
condom use
breaks in skin / mucosa

Question 11

what are the life expectancy & QoL of living with HIV?

Answer 11

77 years
early detection, treatment, adherence, healthy living: smoking, alcohol, drugs, exercise

late detection = worse prognosis

Question 12

what are the HIV diagnostic tests?

Answer 12

blood tests:
HIV antigen (made by virus)
HIV antibody (made by host immune)
test BOTH (within 4-6 weeks post infection), results same day
may get false negative result (so they are positive)

Question 13

what are the more rapid HIV diagnostic tests?

Answer 13

low cost < 1 hour
1. finger prick blood test
2. oral saliva
3. in-home tests
postal testing

if negative - V accurate
can get false positive

Question 14

which patients should be tested for HIV?

Answer 14

resp: bac pneumoniae, TB
neuro: aseptic meningitis
derm: severe psoriasis
gastro: chronic diarrhoea, weight loss
onco: lymphoma, head & neck
any STI / Hep B / Hep C

(everyone)

Question 15

when do you start HAART? (highly active anti-retrovirus therapy) - treatment for HIV

Answer 15

CD4 < 350 (stage III - advanced)
primary HIV infection / any AIDS defining illness
other illness: Hep B/C, syphilis (STD), cancer / lymphoma, heart disease

(treat ASAP, regardless of CD4)

Question 16

what are the aims of HIV treatment?

Answer 16

undetectable HIV viral load (CD4 doesn't decrease)
reconstituted immune system
good QoL
normalised LIFESPAN
reduced risk of TRANSMISSION

Question 17

what are the stages of trying to prevent viral replication?

Answer 17

1. prevent HIV from entering cell
2. prevent ss viral RNA replication (ds DNA - reverse transcriptase)
3. prevent maturation of new HIV cells (post budding)

Question 18

how many drugs used to treat HIV?

Answer 18

virus mutates V quickly (retrovirus) - can become resistant to drugs
1 drug - resistance develops V quickly
3 drugs - harder to develop resistance

patients must KEEP TAKING DRUGS

Question 19

which drugs are used to treat HIV?

Answer 19

NRTI x 2 + NNRTI or Protease inhibitor or integrase inhibitor

NRTI (nucleotide reverse transcriptase inhibitors)