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HIV (1) Flashcards

1
Q

What is HIV?

A

Retrovirus

- Uses reverse transcriptase enzyme to make a second RNA strand

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2
Q

What are other retorviruses?

A

HepB

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3
Q

What is HIV-2?

A

less virulent than HIV-1

Doesn’t necessarily result in AIDS

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4
Q

What is HIV-1?

A

Group M- Responsible for the AIDS pandemic

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5
Q

Significance of CD4 in HVI

A

CD4+ receptors are the target site for HIV

CD4 (Cluster of Differentiation) is a glycoprotein found on the surface of a range of cells including:

  • T helper lymphocytes (“CD4+ cells”)
  • Dendritic cells
  • Macrophages
  • Microglial cells
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6
Q

What is the function of CD4+ Th lymphocytes?

A

Messenger cells
Communicate cytokine release for inducing inflammation
Recognition of MHC2 antigen-presenting cell
Activation of B-cells
Activation of cytotoxic T-cells (CD8+)
Cytokine release

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7
Q

Effect of HIV infection on immune response

A

Sequestration of cells in lymphoid tissues
- Reduced circulating CD4+ cells

Reduced proliferation of CD4+ cells

Reduction CD8+ (cytotoxic) T cell activation

  • Dysregulated expression of cytokines
  • Increasing susceptibility to viral infections (including HIV!)
Reduction in antibody class switching
  - Reduced affinity of antibodies produced

Chronic Immune Activation (microbial translocation)

All the above lead to increased susceptibility to infections (viral, fungal and mycobacterial) and infection induced cancers

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8
Q

What are the CD4+ Th cell parameters?

A

Normal: 500-1600 cells/mm3

Risk of opportunistic infections: <200 cells/mm3

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9
Q

What is the avg time to death without treatment?

A

9-11 yrs

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10
Q

Describe the infection of HIV

A

Infection of mucosal CD4 cell (Langerhans and Dendritic cells)

Transport to regional lymph nodes

Infection established within 3 days of entry
- this is why there is a 72hr window to initiate prophylaxis

Dissemination of virus

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11
Q

Onset and symptoms of primary HIV infection

A

80% are symptomatic
Onset average 2-4 weeks after infection

Combination of flu-ey symptoms and/or glandular fever: 
Fever
Rash (maculopapular)
Myalgia
Pharyngitis
Headache/aseptic meningitis

Very high risk of transmission

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12
Q

What occurs during asymptomatic HIV infection?

A

Ongoing viral replication

Ongoing CD4 count depletion

Ongoing immune activation

Risk of onward transmission if remains undiagnosed

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13
Q

What are opportunistic infections?

A

Infection caused by a pathogen that does not normally produce disease in a healthy individual.

It uses the “opportunity” afforded by a weakened immune system to cause disease

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14
Q

What is the most common opportunistic infection in HIV AIDS? What is the CD4 threshold? **

A

Pneumocystis Pneumonia

CD4 threshold < 200

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15
Q

What is the organism behind pneumocystis pneumonia?

A

Pneumocystis jiroveci

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16
Q

What are the symptoms and signs of pneumocystis pneumonia

A

Symptoms: insidious onset
SOB
Dry cough (most likely presentation)
Signs: exercise desaturation -

CXR: May be normal
Interstitial infiltrates, reticulonodular markings

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17
Q

Diagnosis of Pneumocysts pneumonia

A

BAL and immunofluorescence

+/- PCR

18
Q

Treatment and prophylaxis of P pneumonia

A

Treatment: high dose co-trimoxazole (+/- steroid)
Prophylaxis: low dose co-trimoxazole

19
Q

Tuberculosis and HIV

A

Epidemiological synergy

The following are more common in HIV+ than HIV- individuals

Symptomatic primary infection
Reactivation of latent TB
Lymphadenopathies
Miliary TB
Extrapulmonary TB
Multi-drug resistant TB
Immune reconstitution syndrome

Beware of drug-drug interactions

20
Q

Symptoms/signs of Cerebral Toxoplasmosis in HIV

A

Symptoms/signs

Headache
Fever
Focal neurology
Seizures
Reduced consciousness
Raised intracranial pressure
21
Q

Neurological presentations of HIV

A

Presentation:
Reduced visual acuity
Floaters
Abdo pain, diarrhoea, PR bleeding

Ophthalmic screening for all individuals CD4 <50

22
Q

List the skin infections associated with HIV

A

Herpes Zoster

  • Multidermatomal
  • Recurrent

Herpes Simplex

  • Extensive
  • Hypertrophic
  • Aciclovir resistant

Human papilloma virus

  • Extensive
  • Recalcitrant
  • Dysplastic - women need regular cervical screening

Weird/wonderful

  • Penicilliosis
  • Histoplasmosis
23
Q

Neuro-cognitive impairment with HIV

A

Organism: HIV-1

CD4 threshold: Any. ↑ incidence with ↑ immunosuppression

Presentation:
Reduced short term memory
+/- motor dysfunction

24
Q

Progressive multifocal leukoencephalopathy with HIV

A

Organism: JC virus
Reactivation of latent infection

CD4 threshold: <100

Presentation:  
Rapidly progressing
Focal neurology
Confusion
Personality change
25
Q

Aetiology of HIV associated wasting

A

AKA “slim’s disease”

Aetiologies:
Metabolic (chronic immune activation)
Anorexia (multifactorial)
Malabsorption/diarrhoea
Hypogonadism
26
Q

List the AIDS related cancers

A
  1. Kaposi’s sarcoma
  2. Non-hodgkins lymphoma
  3. Cervical cancer
27
Q

Summary of Kaposi’s sarcoma in AIDS

A

Human Herpes Virus 8
Pathology: vascular tumour

CD4 threshold: Any. ↑ incidence with ↑ immunosuppression

Presentation:
Cutaneous
Mucosal
Visceral – pulmonary, GI

Treatment:
HAART
Local therapies
Systemic chemotherapy

28
Q

Summary of Non-Hodgkins lymphoma in AIDS

A

Organisms: EBV (Burkitt’s lymphoma, primary CNS lymphoma)
CD4 threshold: ↑ incidence with ↑ immunosuppression

Presentation:
More advanced
B symptoms
Bone marrow involvement
Extranodal disease
↑ CNS involvement

Diagnosis: as for HIV-
Treatment: as for HIV-, add HAART
Prognosis: approaching HIV-

29
Q

Aids related cervical cancer

A

Organism: human papillomavirus
Persistence of HPV infection
Rapid progression to severe dysplasias and invasive disease

HIV testing should be offered to all complicated HPV disease
Recalcitrant warts
High grade CIN, VIN, AIN, PIN

30
Q

Haematologic Manifestations of HIV

A 
Caused by:
HIV
Opportunistic infections (MAI)
AIDS-malignancies
(HIV drugs)

CD4 threshold: Any. ↑ incidence with ↑ immunosuppression

Anaemia (affects up to 90%)
Thrombocytopenia (ITP) – (CD4 300-600)

31
Q

Non OI symptomatic HIV

A 
Mucosal candidiasis
Seborrhoeic dermatitis
Diarrhoea
Fatigue
Worsening psoriasis
Lymphadenopathy
Parotitis
Epidemiologically linked conditions
    STIs 
    Hepatitis B
    Hepatitis C
32
Q

List the modes of transmission of HIV

A
  1. Sexual
    - sex b/w men
    - sex b/w men and women
  2. Parenteral
    - injection drug use
    - infected blood products
    - Iatrogenic
  3. Mother-to-child
    - In utero/trans-placental
    - delivery
    - breast feeding
33
Q

Which is the risk group with highest proportion of HIV in the UK?

A

MSM

34
Q

Why are individuals living with HIV in the UK undiagnosed?

A

Late diagnosis
Morbidity/mortality
Onward transmission

35
Q

Which group is most likely to be undiagnosed of HIV?

A

Heterosexual men

36
Q

Who should be tested for HIV?

A

Universal testing-
in high prevalence areas in the UK (local prevalence >0.2%) HIV testing is recommended to:
a) all general medical
b) admissions
c) all new patients registering at general practice

Opt-out testing in certain clinical settings

Screening of high risk groups

Testing in the presence of “clinical indicators”

37
Q

What are the stages of an HIV infection?

A
  1. Primary infection
  2. Asymptomatic phase
  3. Opportunistic infections
  4. Death
38
Q

Which organism causes cerebral toxoplasmosis? What is the CD4 threshold?

A

Organism: Toxoplasma gondii

CD4 threshold: <150

39
Q

What is the pathophysiology of cerebral toxoplasmosis in the setting of HIV?

A

Reactivation of latent infection
Multiple cerebral abscess
(Chorioretinitis)

40
Q

Which organism causes CMV infection in HIV? What is the CD4 threshold?

A

Organism: CMV

CD4 threshold: <50

41
Q

Pathophysiology and causes of CMV in HIV

A

Reactivation of latent infection

Causes: retinitis, colitis, oesophagitis

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