1: HIV Flashcards
What is HIV
Retrovirus that replicates in CD4 cells and macrophages causing progressive immune dysfunction
Define AIDS
CD4 count less than 200 or presence of AIDS defining illness
How is HIV transmitted
- Sexual (80%)
- Parental
- Vertical (Childbirth, Breastfeeding)
At what viral load should a C-section be performed to deliver baby to HIV mother
Viral load is greater-than 50 a women should have a c-section
Can HIV mothers breastfeed
NO
What are 5 RF for HIV
MSM
Multiple Sexual partners
Unprotected Sex
Needle-sharing
Unsterilised procedures
IVDU
Viral load: undetectable means untransmissable
What is the risk of obtaining HIV through needle-stick injury
less than 1 in 300
What is the risk of transmitting Hep C via needlestick
2 in 100
In what % of individuals is seroconversion (primary HIV) symptomatic
80
when does primary conversion present
2-4W following infection
what are symptoms of primary HIV infection
- Flu-like illness
- Malaise
- Sore-throat
- Mucosal ulceration
What is a feature of chronic HIV
Persistent generalised lymphadenopathy
what is persistent generalised lymphadenopathy
Enlargement lymph nodes >1cm, in two or more contagious sites persisting beyond 3-months
what causes persistent generalised lymphadenopathy
follicular hyperplasia secondary to HIV
how does chronic HIV present
Asymptomatic - aside from opportunistic infections
What is a mnemonic to remember opportunistic infections that occur CD4 200-500
SHOK
What infections occur in HIV at CD4 200-500
Shingles
Hairy leukoplakia
Oral candidiasis
Kaposi’s sarcoma
What causes shingles
VZV
How does shingles present
Rash in dermatomal position
What causes hairy leukoplakia
EBV
What causes oral thrush
Candida albicans
What causes kaposi’s sarcoma
HHV8
How does Kaposi’s sarcoma present clinically
Purple macules-papules over trunk that can ulcerate
Aside from skin lesions, what can happen in Kaposi’s sarcoma
Involvement of respiratory tract can cause pleural effusion and haemoptysis
How is Kaposi’s sarcoma managed
Radiotherapy and resection of lesions
What is a mnemonic to remember infections that occur at CD4 count 100-200
CCPPH
What infections may occur at CD4 100-200
Cerebral toxoplasmosis Cryptosporidium Progressive multifocal leucoencephalopathy PCP HIV dementia
What does cryptosporidium cause
Diarrhoea
What causes cerebral toxoplasmosis
Toxoplasmosis Gondii
Where is toxoplasmosis gondii acquired from
Cat faeces
How does toxoplasmosis gondii present
- Asymptomatic
- Can present with malaise and headache
What investigation is ordered in cerebral toxoplasmosis
CT
Sabin-Feldman Dye Test
What will be seen on CT scan
Multiple ring-enhancing lesions
How can ring-enhancing lesions in cerebral toxplasmosis be differentiated from those of cerebral abscess
Toxoplasmosis = adjacent to basal ganglia
Cerebral abscess = periphery
How is cerebral toxoplasmosis managed
6W of pyrimethamine and sulphadiazine
What causes PML
JC virus
What does PML cause
Multi-focal demyelination
How is PML investigated
CT - single or multiple enhancing lesions
MRI - demyelinating white matter lesions
What causes PCP
Pneumocystitis Jirovecci
What is the most common HIV opportunistic infection
PCP
How does PCP present clinically
- Dyspneoa
- Dry cough
- Exercise induced desaturations
- Fever
- Few chest signs
What is a common complication of PCP
Pneumothorax
How does a CXR of PCP present
Bilateral interstitial pulmonary infiltrates
What investigation is required in PCP and why
Bronchoalveolar lavage - as CXR usually negative
Explain prophylaxis for PCP
All individuals with CD4 under 200 are given prophylaxis with co-trimoxazole
How are severe cases of PCP managed
Pentamidine
If a patient with PCP has hypoxia, how are they managed
Steroids
What will be seen on CT in HIV dementia
Cortical or subcortical atrophy
How can cryptosporidium diarrhoea be detected
Red cysts on Ziehl-Neelsen stain
What is a mnemonic to remember opportunistic infections CD4 count 50-100
COPA
what are opportunistic infections 50-100
Cryptococcus meningitis
Oesophageal candiasis
Primary CNS lymphoma
Asperigillosis
what is the most common CNS fungal infection
cryptococcus
how does cryptococcus present
Headache
Fever
N+V
Focal Neurological Deficit
what test is used to detect cryptococcus
LP = high opening pressure
India ink stain
what causes oesophageal candiasis
Candida albicans
how does oesophageal candiasis present
dysphagia
odynophagia
how is oesophageal candiasis managed
fluconazole or itraconazole
what causes primary CNS lymphoma
EBV
how does primary CNS lymphoma present on CT
single homogenous enhancing lesion
what is positive in CNS lymphoma
Thallium SPECT positive
how is primary CNS lymphoma managed
steroids
radiation
chemotherapy
what two infections can occur at a CD4 of less than 50
CMV encephalitis
Mycobacterium avium intracellulare
how does mycobacterium avium intracellulare present
Diarrhoea
Abdominal pain
Deranged LFTs
Hepatomegaly
what molecule does HIV bind to on CD4 cells
gp120
what does HIV use gp120 to do
uses gp120 to bind to co-receptors CXCR4 and CCR5
what does HIV require to enter cells
gp120, CCR5 and CXCR4
what type of virus is HIV
viral RNA
what does HIV require to replicate
reverse transcriptase to convert to DNA virus
explain CD4-HIV ratio
HIV initially replicates, there is a decrease in CD4 cells. These cells then launch a counter-attack and HIV decreases. Reaches steady state where HIV gradually increases
what is the first-line test for HIV
rapid point of care testing
what is rapid point of care testing
immunoassay kit that gives rapid result from finger prick or swab
what is the gold-standard test for HIV
4th generation testing
what does the 4th-generation HIV test detect
HIV antibodies and p24 antigen
what is the window period of fourth-generation HIV test
10-days
what is the window period
false negative - time between infection and positive antibody/antigen test
what is viral load
qualification of HIV RNA
what is viral load used for
measure response to anti-retroviral antibodies
why is HIV RNA not diagnostic
high false negative rate
what is nucleic acid testing
viral PCR
what test is used to detect vertical transfer of HIV
nucleic acid testing
why can the 4th generation testing not be used in cases of suspected vertical transfer
maternal autoantibodies can alter ELISA results up to 18-months of age
explain role of CD4 count
not used to diagnose HIV - but used to define AIDS and monitor disease progression
what is current HIV anti-retroviral therapy
individual requires two NRTIs and one of:
- NNRTI
- Protease Inhibitor
- Integrase Inhibitors
what are nucleoside reverse transcriptase inhibitors (NRTIs)
inhibit reverse transcriptase convening HIV RNA to DNA
what NRTI is given in the UK
Truvada: tenofovir and emtricitabine
what is an integrase inhibitor
inhibits HIV DNA entering nucleus of CD4 cells
what is the suffix of integrase inhibitors
‘gravir’
what is the MOA of protease inhibitors
Inhibit protease - required for maturation of particles
what is the role of NNRTIs
Inhibit reverse transcriptase
what is maraviroc
binds CCR5 preventing interaction with gp41
what is enfuvirtide
inhibits gp41
what is PREP
given to individuals who do not have HIV, but are at a high-risk of HIV
what is licensed for PREP
Truvada
what is Truvada
tenofovir and ematricibine
what is PEP
post-exposure prophylaxis
when must PEP be started by
Within 72h of exposure
how long is PEP taken
28-days
what is given as PEP in the UK
Truvada and raltegravir
when should all pregnant women with HIV have commenced ART by
24W
what viral load does a women need a C-section
> 50 copies
explain neonatal PEP
given from birth until 4W - if born to HIV mum
