Flashcards in HIV Deck (70)
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1
What is HIV?
Retrovirus
HIV-2 originated in West African Sootey mangabey
Less virulent
HIV-1 originated in Central/West African chimpanzees: HIV1 group M responsible for global pandemic
2
What is the target site for HIV?
CD4+ receptors
3
What cells are CD4+ receptors found on?
T helper lymphocytes
Dendritic cells
Macrophages
Microglial cells
4
What do CD4+Th lymphocytes do?
Essential for induction of adaptive immune response
Recognition of MHC2 APC
Activation of B cells
Activation of cytotoxic CD8+ T cells
CK release
5
What effect does HIV infection have on immune response?
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)
6
What does HIV increase susceptibility to?
Viral infections
Fungal infections
Mycobacterial infections
Infection-induced cancers
7
At what CD4+Th count is there a risk of opportunistic infection?
<200cells/mm3
Normal is 500-1600
8
Describe HIV viral replication
Rapid in very early and very late infection
New generation every 6-12hours
9
How does HIV spread in the body?
Infection of mucosal CD4 cell (Langerhans/dendritic)
Transport to RLNs
Infection established within 3 days of entry
Dissemination of virus
10
When is the usual onset of HIV?
2-4wks after infection
11
What are the common symptoms of primary HIV infection?
Fever
Rash (maculopapular)
Myalgia
Pharyngitis
Headache/aseptic meningitis
Up to 80% present with symptoms
12
What happens during the asymptomatic HIV infection?
Ongoing replication
Ongoing CD4 count depletion
Ongoing immune activation
Risk of onward transmission if remains undiagnosed
13
What is an opportunistic infection?
An 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
14
What organism causes pneumocystis pneumonia?
Pneumocystis jiroveci
15
What are the symptoms and signs of pneumocystis pneumonia?
Insidious onset
SOB
Dry Cough
Exercise desaturation
16
How is pneumocystis pneumonia diagnosed?
CXR: May be normal, interstitial infiltrates, reticulonodular markings
BAL and immunofluorescence +- PCR
17
What is the treatment and prophylaxis for pneumocystis pneumonia?
Rx- High dose co-trimoxazole (+- steroid)
Proph: Low dose co-trimoxazole
18
What tuberculosis infections/conditions 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
19
What organism causes cerebral toxoplasmosis?
Toxoplasma gondii
20
What happens in cerebral toxoplasmosis?
Reactivation of latent infection
Multiple cerebral abscess (chorioretinitis)
21
What are the symptoms/signs in cerebral toxoplasmosis?
Headache
Fever
Focal neurology
Seizures
Reduced consciousness
Raised intracranial pressure
22
What does CMV cause?
Retinitis, colitis, oesophagitis
23
How does CMV present?
Reduced visual acuity
Floaters
Abdo pain
Diarrhoea
PR bleeding
24
What skin infections can be due to HIV?
Herpes Zoster: Multidermatomal, Recurrent
Herpes Simplex: Extensive, Hypertrophic, Aciclovir resistant
Human papilloma virus: Extensive, Recalcitrant, Dysplastic
Penicilliosis
Histoplasmosis
25
What causes HIV-associated neurocognitive impairment?
HIV-1
26
How does HIV-associated neurocognitive impairment present?
Reduced STM
+- motor dysfunction
27
What causes progressive multifocal leukoencephalopathy?
JC virus
Reactivation of latent infection
28
How does progressive multifocal leukoencephalopathy present?
Rapidly progressing
Focal neurology
Confusion
Personality change
29
What are some other neurological presentations of HIV?
Distal sensory polyneuropathy
Mononeuritis multiplex
Vacuolar myelopathy
Aseptic meningitis
Guillan-Barre syndrome
Viral meningitis (CMV, HSV)
Cryptococcal meningitis
Neurosyphilis
30
