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Infection * > S6 HIV > Flashcards

S6 HIV Flashcards

1
Q

What are some common signs of HIV?

A
  • oral candidiasis (white plaques in mouth)
  • Kaposi’s sarcoma (skin lesions)
  • PCP (pneumocystis pneumonia)
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2
Q

What are the main pathogens that can cause HIV?

A
  • virus - reactivation of latent infections e.g. shingles

* fungus - yeast, moulded, protozoa

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3
Q

What are the outcomes of HIV?

A
  • there’s no cure
  • usually leads to chronic infection with/without disability
  • death (more likely with late diagnosis and untreated)
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4
Q

Which group is most at risk of HIV acquisition?

A

Men-who-sleep-with-men (MSM)

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5
Q

Are HIV incidence rates increasing or falling?

A

Falling

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6
Q

What are the 4 main features of viral structure?

A
  1. Is the genome DNA or RNA?
  2. Capsid (protein shell) - protects the genome, is this helical or icosahedral?
  3. Has it got a lipid envelope?
  4. What is its replication strategy
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7
Q

What sort of virus is HIV?

A

It is a retrovirus

  • has single stranded RNA which is converted to DNA in the host cell and is integrated into the host cell DNA which is then replicated producing single stranded RNA in a new viral cell
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8
Q

What cells does HIV infect?

A

Cells with the CD4 surface receptor

  • T-helper lymphocytes
  • monocytes/macrophages
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9
Q

What is the process of HIV replication (8 steps)?

A
  1. The free virus binds to the CD4 molecule and a co-receptor and fuses with the cell
  2. The virus penetrates the cell and the contents are emptied into the cell
  3. Reverse transcription occurs (ssRNA into DNA)
  4. Viral DNA is incorporated into human DNA by integrate
  5. The viral DNA is transcribed and viral proteins are made
  6. The viral protein chains come together
  7. Immature virus push out of the cell and take some of cell membrane
  8. Virus matures - proteins changing are cut by proteases into individual proteins that combine to make a working virus
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10
Q

How is HIV transmitted?

A

Contact of infected bodily fluids with mucosal tissue/blood/broken skin

  • sexual contact
  • transfusion
  • contaminated needles
  • perinatal transmission
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11
Q

What are the stages in HIV?

A
  1. Primary infection - high CD4 cell count drops, patient is very infectious
  2. Latent infection - patient becomes much less infectious, CD4 count starts to rise, viral load is at its lowest (set-point)
  3. Symptomatic infection - CD4 count decreases, patient becomes more infectious
  4. Severe infection/AIDS - CD4 count decreases further, patient becomes more infectious still
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12
Q

When does the CD4 cell count become a problem?

A

When below 350cells/microlitre

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13
Q

Why does the viral set-point of viral load vary?

A

Varies dependent on the patients immune system

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14
Q

What is the viral load?

A

How infectious a patient is

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15
Q

What are the main symptoms of acute HIV?

A
  • systemic - fever, weight loss
  • central - malaise, headache, neuropathy
  • pharyngitis
  • mouth - stored, thrush
  • lymph nodes - lymphadenopathy
  • esophagus - sores
  • skin - rash
  • muscles - myalgia
  • liver and spleen - enlargement
  • gastric - nausea and vomiting
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16
Q

What are the main symptoms of severe HIV?

A
  • brain - cryptococcal meningitis
  • eyes - cytomegalovirus (CMV)
  • heart - heart disease, stroke
  • mouth and throat - cold sores and ulcers, thrush
  • liver - hepatitis C
  • stomach - cytomegalovirus (CMV)
  • blood - hyperglycaemia, dyslipidemia
  • lungs - TB
  • bone - osteoporosis
  • reproductive organs - HPV, genital ulcers, menstrual problems, candidiasis
  • body - HIV wasting syndrome
17
Q

What factors affect HIV transmission?

A
  • the type of exposure
  • viral load (viral level in blood)
  • condom use
  • breaks in the skin/mucosa
18
Q

What types of exposure has the highest and lowest risks of HIV transmission?

A

Highest - blood transfusion

Lowest - insertive anal intercourse and oral sex

19
Q

What is the life expectancy for someone who is HIV positive?

A

78 years (general population is about 80 years) if diagnosed early, good treatment, etc.

20
Q

What diagnostic tests do you use to test for HIV?

A
  • serology - for HIV antigen and antibody (blood test)
  • PCR - for HIV nucleic acid (blood test)
  • home testing kits - oral, finger-prick blood tests (fast)
21
Q

Who should be tested?

A

Everyone (especially if rate of HIV is higher in a population)

Or anyone with anything a bit unusual e.g. TB, meningitis, recurrent shingles, weight loss, unexplained blood abnormality, hepatitis C, etc.

22
Q

What is the main drug used for reducing HIV prevalence?

A

Anti-Retrovir all drugs (AVRs)

23
Q

What are the aims of HIV treatment?

A
  • an undetectable viral load
  • a normalised/increased CD4 count
  • reduced general inflammation
  • reduced risk of transmission (if undetectable, untransmissable)
  • good quality of life
  • normalised lifespan
24
Q

What parts of HIV replication do drugs target?

A

Enzymes/proteins involved

  • co-receptors
  • reverse transcriptase
  • integrase
  • protease
25
Q

When should start HIV treatment?

A

ASAP, regardless of CD4 count

26
Q

What is the combination of anti-retroviral drugs you use?

A
  • 2 nucleoside reverse transcriptase inhibitors
    and
  • non-nucleoside reverse transcriptase inhibitor or protease inhibitor or integrase inhibitor or CCR5 (co-receptor) inhibitor
27
Q

Why do we give 3 anti-retroviral drugs?

A

There are many rounds of viral replication a day, and the virus mutates regularly so resistance to drugs develops in days so having more drugs makes it harder for the virus to develop resistance. But the patient must keep taking the drug for this to work.

28
Q

What are the main strategies used for reducing HIV prevalence?

A
  • increased condom usage
  • ARV treatment as prevention
  • wide-spread testing
  • prevention of mother-to-child transmission
  • PEPs and PrEPs (post and pre exposure prophylaxis)
    Ideally want a combination of the above
29
Q

What are the ethical dilemmas involved with HIV?

A
  • psychological impact of the diagnosis
  • dealing with stigma
  • patient confidentiality vs health of sexual contact, any children, risk of patients/staff at workplace

Infection * (18 decks)

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