HIV: what, how, who? Flashcards
what is AIDS?
-causes what 2 major pathologies (2)
Acquired immunodeficiency syndrome
-oppertunistic infections
AIDS- related cancers
What is HIV?
A retrovirus
HIV-2
HIV-1, originated from chimps, caused global pandemic
What is CD4?
-relevance of the receptors?
It is a glycoprotein found on surface of: T helper lymphocytes, Dendritic cells, Macrophages, Microglial cells
-CD4+ receptors are the target site for HIV
What do CD4+ Th lymphocytes do?
induce the adaptive immune response (recognition of the MHC2 antigen-presenting cell Activation of B-cells Activation of cytotoxic T-cells cytokine release)
What effect does HIV infection have on immune response? (5)
-means susceptibility to what? (4)
-sequestration of cells in lymphoid tissue
(reduction in circulation CD4 cells)
-reduced proliferation of CD4 cells
-Reduction in CD8+ (cytotoxic) T cell activation
(disregulated expression of cytokines & increased susceptibility to viral infections)
-Reduction in antibody class switching
(reduced affinity of antibodies produced)
-Chronic immune activation
(microbial translocation)
-viral inf, fungal inf, mycobacterial infections, infection induced cancers
CD4+ T cell parameters:
- normal?
- risk of opportunistic infection?
- 500-1600 cells/mm3
- <200 cells/mm3
Describe the immmunopathogenesis in terms of Viral load and CD4 level in:
- early infection?
- after 6 weeks
- late stage?
- what is the incubation period, why is this clinically relevant?
- Massive spike in viral load and then CD4 cells
- viral load comes down and cells recover but not to premorbid level
- virus load increases again and the CD4 count plummets, eventual death without treatment
- infection established within 3 days of entry, this is the window in which you can start them on prophylaxis
Primary HIV infection
- how long does it take for people to present after infection?
- presentation?
- risk of transmission?
-up to 80% present with symptoms 2-4 weeks after infection
-Fever maculopapular rash Myalgia Pharyngitis Headache/aseptic meningitis
-very high risk of transmission
Asymptomatic HIV infection
- what happens with viral replication?
- CD4 count?
- is there a risk of transmission?
- ongoing
- CD4 count depletion
- risk of transmission ongoing
Opportunistic infection
- definition?
- Give examples of the organisms that cause these
infection caused by a pathogen that does not normally produce disease in a healthy individual, uses the opportunity of a weakened immune system to cause disease
-Pneumocystis jiroveci TB Toxoplasma gondii CMV herpes zoster Herpes simplex Human papilloma virus HIV-1 JC virus
Pneumocystis pneumonia
- Causative organism?
- CD4 threshold?
- symptoms? (3)
- signs? (1)
- CXR appearance?
- Dx via what 3 tests?
- treatment & Prophylaxis? (2)
- Pneumocystis jiroveci
- <200
-insidious onset
SOB
Dry cough
- exercise desaturation
- normal or interstitial infiltrates, reticulonodular markings
-BAL & immunofluorescence
+/- PCR
-High dose co-trimoxazole (+/- steroids)
low dose co-trimoxazole
list the symptoms of TB that are more common in HIV+ individuals?
symptomatic primary infection Reactivation in latent TB Lymphadenopathy Military TB Extra pulmonary TB Multi drug resistant TB Immune reconstruction syndrome
cerebral toxoplasmosis
- causative organism?
- CD4 threshold?
- symptoms & signs? (6)
- what is seen on MRI? (1)
- Toxoplasma gondii
- <150
-headache fever focal neurology seizures reduced consciousness raised intracranial pressure
-ring enhancing lesions in brain
Cytomegalovirus
- causative organism?
- CD4 threshold?
- causes? (3)
- presentation? (3)
- CMV
- <50
- retinitis, Colitis, oesophagitis
-reduced visual acuity
floaters
Abdo pain, diarrhoea, PR bleeding
name the organisms more likely to cause skin infection? (5)
Herpes Zoster Herpes simplex HPV Penicilliosis Histoplasmosis
