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Infection > HIV > Flashcards

HIV Flashcards

1
Q

first identified in the

A

early 1980s

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2
Q

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

A

as life expectancy with disease increases.

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3
Q

HIV specifically affects

A

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

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4
Q

extent of HIV is estimated by

A

patients CD4 T cell count

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5
Q

stage 1

A

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

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6
Q

Stage II

A

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

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7
Q

Stage III

A

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

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8
Q

Stage IV

A

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

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9
Q

clinical stages

A

seroconversion

latent stage

AIDs

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10
Q

serconversion

A

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.

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11
Q

Latent stage

A
  • 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.
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12
Q

AIDS

A
  • when CD4+ count drops below 200 cells/μL and opportunistic infections begin to take hold.
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13
Q

AIDS is the

A

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

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14
Q

AIDS patients are susceptible to

A

opportunistic infections:  Pneumocystis pneumonioa  Candidiasis  Protozal infections

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15
Q

Patient risk factors

A
  • Anyone
  • IV drug abusers
  • Unprotected sex
  • Having another STI
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16
Q

HIV pathogen is a

A

retrovirus

(ssRNA –> DNA –> ssRNA)

  • Infects cells with CD4 surface receptors (T helper lymphocytes)
  • HIV replicates inside cells
17
Q

Life cycle of HIV

A
  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
18
Q

patient symptoms

A
  • Flu-like symptoms
  • Oral candidiasis
  • Liver and spleen enlargement
  • Nausea and vomiting
  • Rash
19
Q

Acute HIV infection main symptoms

A
  • central malais
  • systmeic fever
  • weight loss
  • pharyngitis
  • mouth sores
  • thrush
  • myalgia
  • rash
  • liver and spleen enlargment
  • nausea and vomiting
20
Q

main symptoms of AIDS

A
  • Encephalitis
  • meningitis
  • retinitis
  • pneumocystisi pneumonia
  • TB
  • Tumors
  • esophagitis
  • chronic diarrhea
21
Q

mode of tranmission

A

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).

22
Q

treatment is

A

not curative but will increase life expectancy

23
Q

The earlier HIV is diagnosed, the better

A

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

24
Q

types of tests

A

rapid test

serology

PCR

25
Q

Rapid test (Point of care test)

A

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

26
Q

Serology

A
  • 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
27
Q

PCR

A

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

28
Q

Who should be tested?

A
  • 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
29
Q

treatment for HIV

A

a combined therapy

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

30
Q

PEP stands for

A

post-exposure prophylaxis

31
Q

post-exposure prophylaxis

A

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
32
Q

Ethical dilemmas

A
  • 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
33
Q

Outcome of infection

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

Infection (36 decks)

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