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Year 3 > Human immunodeficiency virus (I) > Flashcards

Human immunodeficiency virus (I) Flashcards

1
Q

What is HIV?

A

Retrovirus that infects and replicates in human lymphocytes and macrophages, resulting in immunodeficiency

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2
Q

Where does HIV primarily replicate in?

A

Human CD4+ T cells and macrophages

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3
Q

What is HIV transmitted via? (4)

A
  • sexual contact / fluids (majority of cases)
    • heterosexual = most common mode of transmission
    • homosexuals are at greater risk in the West
  • before birth or during delivery
  • during breastfeeding (breast milk)
  • blood - sharing contaminated needles and syringes in IVDU / blood transfusions
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4
Q

How does HIV enter CD4+ lymphocytes?

A

Binding to their CD4 molecule + GP120 receptors

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5
Q

Describe the pathophysiology of HIV infection.

A
  • enters CD4+ T cells by binding to CD4 molecule + gp120 receptors
  • retrovirus = uses reverse transcriptase to transcribe complementary double-stranded piece of proviral DNA –> incorporation of HIV genetic material into host genome
  • when immune cell is activated it inadvertently transcribes and translates new HIV virus which bud off from cell membrane to infect more cells
  • –> dissemination of HIV, cell death and eventual CD4+ T cell depletion
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6
Q

What is HIV-1?

A

Responsible for global epidemic

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7
Q

What is HIV-2?

A

Less pathogenic, restricted mostly to West Africa

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8
Q

What is toxoplasmosis (HIV)?

A

Happens in 50% of cerebral lesions in HIV patients

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9
Q

What are the symptoms of toxoplasmosis (HIV)? (4)

A
  • constitutional symptoms
  • headache
  • confusion
  • drowsiness
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10
Q

What imaging do we do for toxoplasmosis (HIV)?

A

CT showing single or multiple ring-enhanced lesions

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11
Q

How do we manage toxoplasmosis (HIV)?

A

Pyrimethamine + sulphadiazine for 6 weeks

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12
Q

What are the stages of HIV infection?

A
  1. seroconversion - transition from infection with HIV to detectable presence of antibodies in blood - symptomatic (60-80%), presents 3-12 weeks after infection
  2. early/asymptomatic
  3. AIDS
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13
Q

What are the clinical features of HIV (stage 1 - seroconversion)? (8)

A

Glandular fever type illness:

  • fever, night sweats, weight loss
  • generalised lymphadenopathy
  • sore throat
  • malaise, myalgia, arthralgia
  • diarrhoea
  • maculopapular rash
  • mouth ulcers
  • rarely: meningoencephalitis
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14
Q

What are the clinical features of HIV (stage 2 - early/asymptomatic)? (4)

A
  • apparently well
  • persistent lymphadenopathy
  • progressive minor Sx - rash, oral thrush, weight loss
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15
Q

What is stage 3 of HIV?

A

AIDS - syndrome secondary disease from immunodeficiency

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16
Q

What are some direct effects from HIV infection? (6)

A
  • neurological - polyneuropathy (peripheral), dementia
  • lung - lymphocytic interstitial pneumonitis
  • heart - myocarditis, cardiomyopathy
  • GI - anorexia, wasting
  • eyes - cotton wool spots
17
Q

What are some secondary effects from immunodeficiency in HIV? (5)

A
  • bacterial infection - TB, skin infections, pneumococcal infections
  • viral - CMV, HSV, VZV, HPV, EBV
  • fungal - candidiasis, Pneumocystis jirovecii pneumonia, Cryptococcus, invasive aspergillosis
  • protozoal - toxoplasmosis
  • tumours - Kaposi sarcoma, SCC, Hodgkin’s/non-Hodgkin’s lymphoma (hepatomegaly/splenomegaly)
18
Q

What are some risk factors for HIV infection? (6)

A
  • HIV-infected blood transfusion
  • IV drug use
  • unprotected sexual intercourse (heterosexual and MSM)
  • percutaneous needle stick injury
  • West Africa residence (HIV-2)
  • maternal HIV infection
19
Q

What are the first-line investigations for HIV? (4)

A
  • serum HIV enzyme-linked immunosorbent assay (ELISA)
  • serum HIV rapid test
  • HIV non-invasive tests
  • serum Western blot
20
Q

What is the standard first-line investigation for HIV infection?

A

Combination test - HIV p24 antigen and HIV antibody test

21
Q

What do we do if combination test (HIV p24 antigen and HIV antibody) is positive for HIV?

A

Repeat to confirm diagnosis alongside starting treatment

22
Q

What is the p24 antigen (HIV)?

A

Viral core protein that appears early in blood as viral RNA levels rise (earlier than antibodies) –> present 1 to 3/4 weeks after exposure

23
Q

How can we detect HIV antibodies

A

Serum HIV enzyme-linked immunosorbent assay (ELISA) - positive for HIV antibodies after 4-6 weeks (however these may not be present in early infection, p24 antigens present early)

24
Q

How can we track immune status in HIV?

A

CD4+ count

25
Q

What are some differential diagnoses for HIV? (7)

A
  • infectious mononucleosis (fever, lymphadenopathy, pharyngitis, maculopapular rash, EBV +ve)
  • CMV infection (fever, lymphadenopathy, rash, splenomegaly)
  • influenza
  • common cold
  • viral hepatitis (RUQ pain, jaundice)
  • secondary syphilis (maculopapular rash)
  • COVID-19
26
Q

What is the first-line management for HIV infection?

A

Antiretroviral therapy (combination of at least 3 drugs) ASAP:
2 NRTIs + 1 PI/NNRTI

NRTI = nucleotide reverse transcriptase inhibitor
PI = protease inhibitor
NNRT = non-nucleoside reverse transcriptase inhibitor

27
Q

What NRTIs are there for HIV? (3)

A

2 required for antiretroviral therapy:

  • Zidovudine
  • Abacavir
  • Tenofovir
28
Q

What NNRTIs are there for HIV? (2)

A

1 NNRTI or PI required for antiretroviral therapy:

  • Nevirapine
  • Efavirenz
29
Q

What PIs are there for HIV? (3)

A

1 NNRTI or PI required for antiretroviral therapy:

  • Indinavir
  • Nelfinavir
  • Ritonavir
30
Q

What are some side effects of antiretroviral therapy for HIV?

A
  • NRTI - peripheral neuropathy, renal impairment
  • NNRTI - P450 enzyme interaction, rashes
  • PI - diabetes, hyperlipidaemia, buffalo hump, obesity, P450 inhibition, renal stones
31
Q

What other drugs are there HIV antiretroviral therapy? (2)

A
  • entry inhibitors - prevent HIV-1 from entering and infecting immune cells
  • integrase inhibitors - block enzyme that inserts viral genome into host DNA
32
Q

What supportive care do we provide for HIV? (5)

A
  • counselling
  • prophylaxis of opportunistic infections
  • treating other infections
  • comorbidity management
  • vaccinations - pneumococcal, meningococcal, influenza, hepatitis B, HPV, tetanus/diphtheria/pertussis
33
Q

How do we prevent HIV in high-risk individuals?

A

HIV Pre-Exposure Prophylaxis (PrEP) - Tenofovir (daily use to reduce transmission)

34
Q

What do we give patients up to 72 hours after potential exposure to HIV?

A

HIV Post-Exposure Prophylaxis (PEP) which is a short course of antiretroviral therapy for 4 weeks

35
Q

What do we give for HIV if CD4+ count <200mm3?

A

Co-trimoxazole as prophylaxis against Pneumocystis jirovecii pneumonia

36
Q

How do we monitor HIV patients?

A

HIV RNA testing after ART initiation until levels below detection limits - 2,4,8 weeks then evert 2 weeks

Once viral suppression achieved - repeat every 3-6 months

37
Q

What are some complications of HIV? (5)

A
  • acute seroconversion
  • AIDS
  • opportunistic infections - candidiasis, Pneumocystis jirovecii pneumonia, recurrent pneumonia, toxoplasmosis, HIV encephalopathy
  • secondary malignancies
  • neuropsychiatric disease
38
Q

Describe the prognosis of HIV.

A

If untreated, leads to death on average 8-10 years after infection

If receiving adequate ART, no changes in life expectancy to healthy individuals

Year 3 (164 decks)

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