HIV Flashcards
What type of virus is HIV?
RNA retrovirus
Describe the different types of HIV
HIV1 - group M responsible from the global epidemic
HIV2 - localised to west Africa, few cases in the UK
When does replication occur in HIV?
Very late and very early infection - new generation every 6-12 hours
What cells are infected in HIV?
CD4+ cells in the mucosal tissue then transfers into the blood stream via lymphatic drainage
How soon is infection established in the body?
72 hours
What is the target site for HIV?
T helper lymphocytes
State the four functions of T helper lymphocytes
- recognise MHC2 antigen presenting cells
- activate B cells
- activate cytotoxic T cells
- cytokine release
How does HIV alter immune system?
Reduced circulation and proliferation of CD4+ T cells
Reduced CD8+ T cells
Reduced antibody affinity
Chronic immune activation (microbial translocation -GALT)
What is normal CD4 T cell count?
500-1600 cells/mm3
At what CD4 T cell level is there the highest risk fo opportunistic infections?
<200 cells/mm3
What are the four key stages in HIV infection?
Primary
Asymptomatic
Symptomatic
AIDS
With no treatment how long does HIV take to progress from primary to AIDS?
9-11 years
How many people present with HIV primary infection?
80%, 2-4 weeks after infection
How does primary HIV present?
Fever, maculopapular rash, myalgia, pharyngitis, headache, aseptic meningitis
What happens in the asymptomatic phase?
Ongoing viral replication, CD4 depletion, immune activation and risk of onward transmission
Define opportunistic infections
An infection that pathogen does not normally cause disease in a healthy individual
What infection can HIV cause in the lungs?
Pneumocystic Pneumonia
When does PCP occur and what are the signs/symptoms?
CD4 <200
Symptoms - insidious onset, SOB, dry cough
Signs - exercise oxygen desaturation (pulse up and oxygen down fast)
What will a CXR of PCP show?
Normal, interstitial infiltrates, reticulonodular markings
How is PCP diagnosed?
Broncho-alveolar lavage, PCR/immunoflorescence
How is PCP treatment?
High dose co-trimoxazole
What types of TB are more common in HIV positive patients?
Symptomatic primary infection, reactivation of latent TB, lymphadenopathies, miliary TB, extra pulmonary TB, multi-drug resistant, immune reconstitution syndrome
What organism causes cerebral toxoplasmosis?
Toxoplasma gondii
At what CD4 count can cerebral toxoplasmosis occur?
<150
What can reactivation of toxoplasma gondii cause?
Cerebral abscess
Chorioretinitis
How will cerebral toxoplasmosis present?
Headache, fever, seizures, focal neurology, reduced consciousness, raised ICP
What will a CT of toxoplasmosis show?
Multiple ring enhancing lesions
At what CD4 count can cytomegalovirus occur?
<50
What screening is done for CMV?
Ophthalmic screening
Name the consequences of reactivated CMV
Retinitis
Colitis
Oesophagus
How does reactivation of CMV present?
Reduced visual acuity, floaters, abdominal pain, PR bleeding can lead to blindness
How can HIV associated neurocognitive impairment present?
Reduced short term memory +/- motor dysfunction
How will neurocognitive HIV impairment appear on CT?
Enlarged ventricles - signs of atrophy
What can JC virus reactivation cause?
Progressive multifocal leukoencephalopathy
At what level of CD4 will PML present and how will it present?
<100
Rapidly progressing, focal neurology, confusion, personality change
MS type picture
Name three skin infections HIV can increase your chance of getting
- herpes zoster (multidermatomal/recurrent)
- herpes simplex (extensive, treatment resistant)
- HPV (chance of dysplasia)
What can cause HIV associated wasting?
Metabolic immune activation Anorexia Malabsorption HIV enteropathy Hypogonadism
What tumour can herpes virus 8 cause?
Kaposi’s Sarcoma - vascular tumour
How will kaposi’s sarcoma present?
Cutaneous, mucosal, visceral (pulmonary, GI)
How is kaposi’s sarcoma treated?
Anti-retroviral, local therapies, systemic chemo
What haematological malignancy can HIV cause?
Non-Hodgkins lymphoma
When can non-AIDS symptomatic HIV occur?
During asymptomatic phase
State factors that increase transmission of HIV
Anoreceptive sex
Trauma
Genital ulceration
Concurrent STI
Why is the rectum more easy to transmit HIV compared to the vagina?
It is only 1 cell thick and has lots of lymphoid tissue
Name three ways HIV can be transmitted
Parenteral
Mother to child
How can HIV be transmitted parenterally?
Injection drug use
Infected blood produced
Iatrogenic
How can HIV be transmitted from mother to child ?
In utero
Delivery
Breast feeding
Where is HIV a pandemic?
Sub Saharan Africa
Caribbean
South East Asia
Where is HIV an epidemic ?
Russia
Eastern Europe
What percentage of people are misdiagnosed in the UK?
6%
Name four testing techniques for HIV testing
Universal testing
Opt-out testing
Screening high risk groups
Testing on clinical grounds
Name high risk groups
MSM Female partners MSM Black Africans Prisoners Trans women PWID Partners of people living with HIV Endemic areas
Name blood markers measured in HIV
- antibodies (3 months to become detectable)
- antigen - p24
- viral RNA
Describe a rapid HIV test
Fingerpick blood specimen/saliva get results in 20-30 minutes measures both the antibody and antigen
What prophylaxis treatment can be given for PCP?
Co-trimoxazole 480mg daily
Name four targets of HIV treatment
Reverse transcriptase
Integrase
Protease
Entry to cell - fusion or CC5R receptor
Define highly active anti-retroviral
A combination of 3 drugs from at least 2 classes to which the virus is susceptible
How does drug resistance occur?
Mutations can occur in low compliance leading to resistance
What does U=U mean?
Undetectable = untransmitable
What side effects can occur from anti-retroviral treatment?
GI side effects Skin - rash, hypersensitivity, SJS CNS - mood, psychosis Renal complications Osteomalacia CVD Haematological complications
Describe pre-exposure prophylaxis
2 drugs to prevent acquiring HIV in high risk individuals
- tenofovir and emtricitabine daily or on demand
What are the side effects of PrEP
Renal health can be affected
Drug-drug interactions
Requires regular monitoring
Describe post exposure prophylaxis
72 hours within high risk exposure
Prep and rategravir for 4 weeks
In pregnant women if the viral load is detectable what form of delivery is required?
C section
How long should PEP be given in a neonate?
2-4/52