HIV Flashcards
what does HIV cause
Acquired Immunodeficiency Syndrome (AIDS)
how is AIDS preventable
early HIV diagnosis
what is HIV
retrovirus
what is the target site for HIV
CD4+ receptors
where are CD4+ receptors found
T helper lymphocytes (“CD4+ cells”)
Dentritic cells
Macrophages
Microglial cells
what is the function of CD4+ Th lymphocytes
Essential for induction of adaptive immune response
- Recognition of MHC2 antigen-presenting cel
- activate B cells
- activate cytotoxic T-cells [CD8+]
- cytokine release
what affects does HIV infection have on immune response [5 things]
Reduced circulating CD4+ cells
Reduced proliferation of CD4+ cells
Reduction CD8+ (cytotoxic) T cell activation
Reduction in antibody class switching = Reduced affinity of antibodies produced
Chronic Immune Activation
what does the affect on the immune response that HIV has make people susceptible to
viral infections
fungal infections
mycobacterial infections
infection-induced cancers
what is the normal CD4+ Th cell parameters
500-1600
when is there a risk of opportunistic infections
when CD4+ Th cell < 200
what are the key features of HIV viral replication
rapid replication in very early and very late infection
what cells does the HIV virus first infect
mucosal CD4 cells [Langerhans and Dendritic cells]
transported to regional lymph nodes
infection established within 3 days of entry
when can post-exposure prophylaxis be given and why
within 72 hours of exposure
as the infection needs 3 days to become established
when does the primary HIV infection symptoms occur
2-4 weeks after infection
what are the Sx seen in the primary HIV infection period
fever maculopapular rash myalgia pharyngitis headache/aseptic meningitis
why are people in the primary HIV infection stage high risk
they have high viral load
what is happening during asymptomatic HIV infection
Ongoing viral replication
Ongoing CD4 count depletion
Ongoing immune activation
what is the definition of an opportunistic infection
infection caused by a pathogen that does not normally produce disease in a healthy individual
what type of pneumonia is seen in HIV
pneumocystis pneumonia
what organism causes pneumonia and what CD4 threshold is needed for it to cause Sx
Pneumocystis jiroveci
< 200
Sx of pneumocystis pneumonia
insidious onset
SOB
dry cough
Signs of pneumocystis pneumonia
exercise desaturation - when oxygen saturations drop after exercise
what Ix can be done of pneumocystis pneumonia
CXR = may be normal, interstitial infiltrates, reticulonodular marking
Diagnostic = Bronchoalveolar lavage and immunofluorescence +/- PCR
Tx of pneumocystis pneumonia
high dose co-trimoxazole +/- steroids
what forms of TB are HIV +ve more prone to
Symptomatic primary infection Reactivation of latent TB Lymphadenopathies Miliary TB Extrapulmonary TB Multi-drug resistant TB
what organism causes Cerebral toxoplasmosis and what CD4 threshold is require for it to appear
Toxoplasma gondii = fungal infection
< 150
what is seen on CT of Cerebral toxoplasmosis
multiple ring enhancing lesions
Sx of Cerebral toxoplasmosis
Headache Fever Focal neurology (weakness, sensory problem) Seizures Reduced consciousness Raised ICP
when does CMV cause Sx in HIV
when CD4 <50
what does CMV cause
retinitis
colitis
oesophagitis
how does CMV present
reduced visual acuity floaters abdo pain diarrhoea PR bleeding
what is offered to HIV patients to try prevent serious Sx of CMV
Ophthalmic screening for all individuals with CD4 <50
what skin infections are common in HIV
herpes zoster herpes simplex HPV Penicilliosis Histoplasmosis
what form of HIV is associated with “HIV-associated neurocognitive impairment”
HIV-1
what CD4 threshold in HIV-associated neurocognitive impairment seen
ANY
increased incidence with increased immunosuppression
Sx of HIV-associated neurocognitive impairment
Reduced short term memory
+/- motor dysfunction
what organism causes Progressive multifocal leukoencephalopathy and what CD4 threshold is it seen
JC virus
< 100
Sx of Progressive multifocal leukoencephalopathy
Rapidly progressing
Focal neurology
Confusion
Personality change
what is “Slim’s disease”
HIV-associated wasting/cachexia
what are the cancers related to AIDS
Karposi’s sarcoma
Non-Hodgkins lymphoma
Cervical cancer
what organism is associated with Kaposi’s sarcoma and at what CD4 threshold is it seen
Human herpes virus 8 (HHV8)
Any
however, increased incidence with increased immunosuppression
what is the pathology of a Kaposi’s sarcoma
vascular tumour
where can kaposi’s sarcoma occur
cutaneous
mucosal
visceral - pulmonary, GI
kaposi’s sarcoma Tx
HAART
Local therapies
Systemic chemotherapy
excluding opportunistic HIV, what can be seen in symptomatic HIV
Mucosal candidiasis Seborrhoeic dermatitis Diarrhoea Fatigue Worsening psoriasis Lymphadenopathy Parotitis
what haematology manifestations are seen in HIV
anaemia
thrombocytopenia [commonly ITP]
through what ways is HIV transferred
sexual transmission
parenteral transmission
mother-to-child
how can HIV be transferred mother-to-child
In utero/trans-placental
Delivery
Breast-feeding
where is there opt-out HIV testing
Abortion services GUM clinics Drug dependency services Antenatal services Assisted conception services
what are the high risk groups that are screened for HIV
MSM Females of bisexual partners IVDU Partners of people with HIV Adults from endemic areas Children from endemic areas Sexual partners from endemic areas
what are the endemic areas of HIV
Sub-Saharan Africa
Caribbean
Thailand
what markers are used by the lab to detect HIV infection
RNA
p24 antigen
HIV-1 and HIV-2 [IgM and IgG] antibody (only positive after 3 months of being infected)
what is currently the best test to date for HIV
4th gen HIV test
combined antibody and antigen (p24)
how can the 4th gen HIV test be interpreted
A negative 4th generation test performed at 4 weeks following an exposure is highly likely to exclude HIV infection
what is HAART
Highly active anti-retroviral therapy
i.e. a combination of 3 drugs from at least 2 drug classes to which the virus is susceptible
what is the purpose of HAART therapy
Reduce viral load to undetectable
Restore immunocompetence
Reduce morbidity and mortality
Minimise toxicity (maximise tolerability)
what are examples of single tablet formulations of HAART
Tenofovir
Emtricitabine
Efavirenz
what are examples of HAART side effects
GI = nausea, diarrhoea, abdominal pain, vomiting Skin = rash, hypersensitivity, Stevens-Johnsons syndrome CNS = mood changes, psychosis Renal = proximal renal tublopathies Bone = osteomalacia CVS = increased MI risk Haematology = anaemia
what are conception options for HIV couples where male is +ve, female is -ve
Timed unprotected sex with HAART
Treatment as Prevention
what are conception options for HIV couples where female is +ve, male is -ve
self-insemination
timed unprotected sex with HAART
Tx as prevention
what can be done to prevent transmission of HIV from mother to child
HAART during pregnancy
Vaginal delivery if undetected viral load
Caesarean section if detected viral load
4/52 Post-Exposure Prophylaxis for neonate
Exclusive formula feeding
