Flashcards in HIV: pathophysiology and presentations Deck (68):
What can HIV cause/lead to?
AIDS - Acquired Immunodeficiency Syndrome
What is the life expectancy of people with HIV?
What is HIV?
Originated in Central/West African chimpanzees
Responsible for pandemic starting in 1981
Originated in West African Sootey mangabey (Simian ID virus)
What is CD4?
CD4+ receptors are the target site for HIV
A glycoprotein found on the surface of a range of cells
What cells are CD4 receptors found on?
T helperlymohocytes (CD4+ cells)
What do CD4+ Th lymphocytes do?
Essential for induction of adaptive immune response
Recognition of MHC2 antigen-presenting cell
Activation of B-cells
Activation of cytotoxic T-cells (CD8+)
What does HIV do to the immune response?
Reduced circulating and proliferating of CD4 cells
Dysregulation expression of cytokines
Increased susceptibility to viral infections
Reduced affinity of antibodies produced
What are HIV sufferers susceptible to?
What is the normal range of CD4+Th cells?
What number of CD4+Th cells give risk to opportunistic infections?
Describe HIV viral replication?
Rapid replication in early and late infection
New generation every 6-12 hours
What is the prognosis of HIV without treatment (on average)?
How does the infection take place?
Infection of mucosal CD4 cell (Langerhans and Dendritic cells
Transport to regional lymph nodes
Infection established within 3 days of entry
Dissemination of virus
How long after infection does it take for symptoms to present?
Usually 2-4 weeks
What are the symptoms of a primary HIV infection?
Headache/ aseptic meningitis
What occurs in asymptomatic HIV infection?
Ongoing viral replication
Ongoing CD4 count depletion
Ongoing immune activation
Risk of transmission
What is the definition of an Opportunistic infection?
An infection caused by a pathogen that does not normally produce disease in a healthy individual. But does when afforded the opportunity by a weakened immune system.
What organism causes Pneumocystis pneumonia and what CD4 count is needed for this?
Organism - Pneumocystis jiroveci
CD4 count: <200
What are symptoms and signs of Pneumocystis pneumonia
Symptoms: insidious onset, SOB, dry cough
Signs: Exercise desaturation
How do you diagnose Pneumocystis pneumonia?
BAL and immunoflourescence +/- PCR
What is the treatment and prophylaxis for Pneumocystis pneumonia?
Treatment: High dose co-trimoxazole (+/- steroid)
Prophylaxis: Low dose co-trimoxazole
What other opportunistic infection that effects the respiratory system can occur in HIV?
What organism causes Cerebral Toxoplasmosis and what CD4 level is needed?
Organism: Toxoplasma gondii
CD4 level: <150
What is cerebral toxoplasmosis?
reactivation of latent infection
Multiple cerebral abscess (Chorioretinitis)
What are symptoms/signs of cerebral toxoplasmosis?
What organism causes Cytomegalovirus and what CD4 count is needed?
CD4 level: <50
What is CMV?
Reactivation of latent infection.
What are causes of CMV?
How does CMV present?
Reduced visual acuity
Abdo pain, diarrhoea, PR bleeding
When is screening for CMV done?
Individuals with a CD4 level of <50
What skin infections can occur with HIV?
What is HIV-associated neurocognitive impairment?
Caused by HIV-1
Any reduced CD4 level
How does HIV-associated neurocognitive impairment present?
Reduced short term memory
+/- motor dysfunction
What is Progressive multifocal leukoencephalopathy?
Caused by JC virus
CD4 level of <100
How does Progressive multifocal leukoencephalopathy present?
List some other neurological presentations of HIV?
Distal sensory polyneuropathy
Viral meningitis (CMV, HSV)
What causes kaposi's Sarcoma and what is it?
Human Herpes virus 8 (HHV8)
What CD4 level is needed for Kaposi's sarcoma?
Any reduced level
How does Kaposi's sarcoma present?
Visceral - pulmonary, GI
How do you treat Kaposi's sarcoma?
What organisms cause non-Hodgkins lymphoma and what CD4 level is needed?
EBV (Burkitt's lymphoma), primary CNS lymphoma
Any reduced CD4 level
What is the presentation of non-Hodgkins lymphoma?
Bone marrow involvement
Increased CNS involvement
What is the diagnosis and treatment of non-Hodgkins lymphoma?
Diagnosis - Same as HIV
Treatment: Same as HIV + HAART
What organism causes Cervical cancer?
What is cervical cancer?
Rapid progression to severe dysplasias and invasive disease
Name some non-OI of symptomatic HIV
Fatigue + diarrhoea
What causes haematologic manifestations?
AIDS - malignancies
What are haematological manifestations of HIV?
What CD4 level is needed for haematological manifestations to present?
Any reduced CD4 level
What factors increase the risk of HIV transmission?
What ways can a mother pass HIV on to her child?
What is the prevalence of HIV in the UK?
How many people are living with diagnosed HIV in Tayside?
What markers of HIV are used in labs to detect infection?
RNA (viral genome)
Envelope proteins (gp120)
Capsule protein (p24)
When were HIV antibody tests first introduced?
What is the window period for HIV antibody testing?
What antibodies are detected in 3rd generation HIV?
IgG and IgM
What is the window period for 3rd generation HIV antibody testing?
~average of 20-25 days
Describe 4th generation HIV tests
Combined antibody and antigen (p24)
Shortens window period by ~5 days (around 14-28 days)
Variability between assays and between labs
What is POCT?
A rapid HIV test
results in 20-30 mins
3rd generation (ab only)
4th generation (ab/ag)
What are the advantages of POCT?
Simple to use
No lab needed
No venepuncture needed
No anxious wait
Reduce follow up
What are the disadvantages of POCT?
Poor +ve predictive value in low prevalence settings
Not suitable for high volume
Cant be relied on in early infection
What does RITA stand for?
Used to identify if an infection occured within the preceeding 4-6 months
Measure different types of antibodies or strength of antibody binding
What are the advantages of RITA?
Assess HIV testing programmes
Inform partner notification
Safer sex advice
Interpretation of CD4