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HIV I Flashcards

1
Q

What is HIV?

A

Retrovirus that causes AIDS = leads to opportunistic infections and AIDS related cancers

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2
Q

What is the single highest predictor of mortality in HIV?

A

AIDS related complications

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3
Q

What is the life expectancy of people with treated HIV?

A

Near normal life expectancy

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4
Q

What are the types of HIV?

A 
HIV-1 = group M responsible for global pandemic 
HIV-2 = less virulent
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5
Q

What are the targets of HIV?

A

CD4+ receptors

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6
Q

What is CD4?

A

Glycoprotein found on surface of T helper cells, dendritic cells, macrophages and microglial cells

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7
Q

What are CD4+ T helper cells essential for?

A

Induction of adaptive immune response = recognition of MHC II, activation of B cells and CD8+ T cells, cytokine release

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8
Q

What are the normal CD4+ levels?

A

500-1600 cells/cubic mm = opportunistic infection risk if <200 cells/cubic mm

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9
Q

How does HIV affect the immune response?

A 
Sequesters cells in lymphoid tissues 
Reduces proliferation of CD4+ cells 
Reduces CD8+ T cell activation
Reduction in antibody class switching
Chronic immune activation
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10
Q

What does the sequestering of cells in lymphoid tissues have?

A

Reduces circulating CD4+ cells

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11
Q

What effect does reduced CD8+ T cell activation have?

A

Dysregulated cytokine expression

Increased susceptibility to viral infections

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12
Q

How does HIV replicate?

A

Rapid replication in very early and very late infection = new generation every 6-12 hours

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13
Q

What is the average time till death in untreated HIV?

A

9-11 years

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14
Q

How does HIV infection become established?

A

Infection of mucosal CD4 cell = Langerhans and dendritic cells
Transport to regional lymph nodes
Infection established within 3 days of entry

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15
Q

How long does it take primary HIV infection to present?

A

Onset 2-4 weeks after infection= up to 80% present with symptoms, very high risk of transmission

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16
Q

What are the symptoms of primary HIV infection?

A

Fever, maculopapular rash more marked on trunk, myalgia, pharyngitis, headache/aseptic meningitis

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17
Q

What are some features of asymptomatic HIV infection?

A

Ongoing viral replication, CD4 count depletion and immune activation
Risk of onward transmission if remains untreated

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18
Q

What are opportunistic infections?

A

Infection caused by a pathogen that doesn’t normally produce a disease in a healthy individual

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19
Q

What is pneumocystis pneumonia?

A

Pneumocystis jiroveci infection = occurs if CD4 <200

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20
Q

What are the symptoms of pneumocystis pneumonia?

A

Insidious onset SOB, dry cough and exercise desaturation

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21
Q

What does a CXR of pneumocystis pneumonia show?

A

May be normal

Can show interstitial infiltrates and reticulonodular markings

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22
Q

How is pneumocystis pneumonia diagnosed?

A

BAL and immunofluorescence +/- PCR

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23
Q

What is the treatment for pneumocystis pneumonia?

A

High dose co-trimoxazole (+/- steroids)

Prophylaxis with low dose co-trimoxazole

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24
Q

What is an example of an opportunistic infection that shows epidemiological synergy with HIV?

A

Tuberculosis

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25
Q

What causes cerebral toxoplasmosis?

A

Toxoplasma gondii infection = occurs when CD4 threshold <150

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26
Q

What does a reactivation of cerebral toxoplasmosis cause?

A

Multiple cerebral abscesses

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27
Q

What are the symptoms of cerebral toxoplasmosis?

A

Headache, fever, focal neurology, seizures, reduced consciousness, raised ICP

28
Q

What causes cytomegalovirus?

A

Reactivation of latent CMV infection = due to retinitis, colitis or oesophagitis
Occurs when CD4 threshold <50

29
Q

What are the symptoms of cytomegalovirus?

A

Reduced visual acuity, floaters, abdominal pain, PR bleeding, diarrhoea

30
Q

What should all patients with a CD4 threshold <50 receive?

A

Ophthalmic screening

31
Q

What are some skin infections that can occur in HIV?

A

Herpes zoster = multidermatomal, recurrent
Herpes simplex = hypertrophic, aciclovir resistant
HPV = extensive, recalatriant, dysplastic
Penicillinosis and histoplasmosis

32
Q

What is HIV associated neurocognitive impairment?

A

HIV-1 infection = reduced short term memory +/- motor dysfunction

33
Q

What causes progressive multifocal leukoencephalopathy?

A

Reactivation of latent John Cunningham Virus = occurs when CD4 threshold <100

34
Q

What are the symptoms of progressive multifocal leukoencephalopathy?

A

Rapidly progresses = focal neurology, confusion, personality change

35
Q

What are some neurological presentations of HIV?

A

Distal sensory polyneuropathy, mononeuritis multiplex, vacuolar myelopathy, aseptic meningitis, GB syndrome, viral meningitis, cryptococcal meningitis, neurosyphilis

36
Q

What are some aetiologies of HIV associated wasting?

A

Metabolic = chronic immune activation

Anorexia, malabsorption, hypogonadism

37
Q

What are some examples of AIDS related cancers?

A

Kaposi’s sarcoma, non-Hodgkin’s lymphoma, cervical cancers

38
Q

What causes Kaposi’s sarcoma?

A

Human Herpes virus (HHV) 8 = causes vascular tumour May be cutaneous, mucosal or visceral (pulmonary, GI)

39
Q

What is the treatment of Kaposi’s sarcoma?

A

HAART, local therapies, systemic chemotherapy

40
Q

What are some examples of non-Hodgkin’s lymphomas?

A

Burkitt’s lymphoma, primary CNS lymphoma

41
Q

What causes non-Hodgkin’s lymphomas?

A

Epstein Barr virus = same diagnosis and treatment as for HIV negative patients (add HAART)

42
Q

What are the symptoms of non-Hodgkin’s lymphomas?

A

More advanced B symptoms, bone marrow involvement, extranodal disease, CNS involvement

43
Q

What causes cervical cancers?

A

Persistent HPV infection = test for HIV in all complicated HPV cases
Rapid progression to severe dysplasia and invasive disease

44
Q

What are some non-opportunistic infections and other conditions that can occur in HIV?

A

Mucosal candidiasis, seborrhoeic dermatitis, diarrhoea, fatigue, worsening psoriasis, lymphadenopathy, parotitis, STIs, hepatitis B or C

45
Q

What are some haematological conditions that can occur in HIV?

A

Anaemia affects up to 90%

Thrombocytopenia occurs when CD4 is 300-600

46
Q

How common is sexual transmission of HIV?

A

Accounts for 95% of new infections in the UK

47
Q

What are some factors that increase risk of sexual transmission of HIV?

A

Anoreceptive sex, trauma, genital ulceration, concurrent STI

48
Q

What causes parenteral transmission?

A

Injection drug use = accounts for 2% of new diagnoses in the UK (quite uncommon)
Infected blood products or iatrogenic

49
Q

When can mother to child transmission occur?

A

In utero, during delivery or via breast feeding

50
Q

What is the risk of mother to child transmission occurring?

A

1 in 4 at-risk babies will become infected

Risk <0.1% when viral load undetected at delivery

51
Q

What is the prognosis of “congenital” HIV?

A

1 in 3 HIV positive babies will die before their first birthday if untreated

52
Q

What is the prevalence of HIV in the UK?

A

1.6/1000 in people >= age 15

53
Q

What is the prevalence of HIV in different risk groups?

A

Male/male sex = 1:17
Heterosexuals age 15-44 = 1:1000
IV drug users aged 15-44 = 1:263

54
Q

How common is undiagnosed HIV?

A

7% of people living with HIV in UK are undiagnosed

Heterosexual men are most likely to be undiagnosed

55
Q

Where is universal HIV testing done?

A

In high prevalence areas (>0.2%) = recommended to all general medical admissions and all new patients registering at GP

56
Q

Where are some places that opt out HIV testing is done?

A

Abortion services, GUM clinics, drug dependency services, antenatal services, assisted conception services

57
Q

What are some high risk groups that should be offered HIV testing?

A

Gay men and female partners of bisexual men
People who inject drugs
Partners of people living with HIV
Adults and children from endemic areas
Sexual partners from endemic areas
History of iatrogenic exposure in endemic area

58
Q

What are some areas of high prevalence?

A

Sub-Saharan Africa, Caribbean, Thailand

59
Q

When is it acceptable to test for HIV on clinical grounds?

A

When HIV falls within the differential diagnoses

60
Q

What are some features of taking an HIV test?

A

Document consent or refusal = request via ICE

Obtain venous sampling for serology

61
Q

How should testing for HIV be done in a patient who is incapacitated?

A

Only test if in patient’s best interests
Consent from relative not needed
Wait until patient regains capacity of safe to do so

62
Q

What are some features of third generation HIV antibody tests?

A

HIV-1 and HIV-2 antibody = detect IgG and IgM
Very sensitive in established infection
Window period of 20-25 days

63
Q

What are some features of fourth generation HIV antibody tests?

A

Combined antigen and antibody (p24)

Shortens window period to 14-28 days

64
Q

What are some features of a rapid HIV test (POCT)?

A

Fingerprick blood sample or saliva
Results within 20-30 mins
Third or fourth generation

65
Q

What are the advantages of a rapid HIV test (POCT)?

A

Simple to use and no lab required
No venepuncture needed
Reduce follow up and good sensitivity

66
Q

What are the disadvantages of a rapid HIV test (POCT)?

A

Expensive (£10) and difficult to quality control
Poor predictive value in low prevalence settings
Not suitable for high volume
Unreliable in early infection

Reproduction (62 decks)

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