HIV Flashcards
What type of HIV causes the global epidemic?
HIV-1 (Type 1), specifically group M
How does HIV infection work?
Virus infects/destroys CD4+ (surface receptor) cells such as macrophages, monocytes, brain cells, skin and most importantly Th cells.
Eventually the CD4 count gets low enough for infections and tumours to develop
What is AIDS?
Acquired Immunodeficiency Syndrome
Defined by a set of conditions that arise when a HIV patient’s CD4 count gets to around 200.
What are the major sources of HIV?
Sex mostly MSM IV drug Abuse Blood products (Haemophiliacs) Vertical Transplant
How does an acute infection with HIV appear?
Usually its asymptomatic
However 30-60% have seroconversion illness 2-4wks post-exposure:
They get non-specific glandular fever like symptoms for 1-2 wks, the clues that they’re -ve for EBV
e.g. lymphadenopathy, myalgia, rash an headache
How does the chronic HIV infection present?
A long symptomatic phase lasting 7-8yrs on avg.
Then Minor HIV-related illlnesses like thrush
Then when CD4 count gets really low (~200) you get AIDS defining illnesses like TB or Kaposi’s Sarcoma
How do we test for HIV?
Serum or Salivary ELISA to detect antibodies & the viral antigen
Or in babies viral genome detection (they will have the antibody from their mum even if they didn’t get the infection so ELISA useless)
If you test someone post-exposure and it comes back -ve repeat in a month or 2 as theres a window of false -ves post infection
Give some examples of AIDS defining conditions that would indicate an HIV test?
TB Pneumocystis Pneumonia PML Cryptococcal Meningitis Kaposi's Sarcoma Persistant Cryptosporidiosis Non-hodgkin's Lymphoma Cervical Cancer CMV retinitis
Give some examples of HIV-associated conditions that would indicate an HIV test?
Oral thrush Unexplained weight loss Unexplained lymphadenopathy Guillain-Barre Dementia Aspergillosis Anal or Lung Cancer
How do we prevent HIV infections?
1) Behaviour changes e.g. condom use
2) Circumcision
3) Treatment (patients treated to get an undetectable viral load can’t transmit)
4) Pre-exposure Prophylaxis (PrEP)
5) Post-exposure Prophylaxis (PEP)
When is PrEP used?
Offered to MSM in scotland
When is PEP used and how does it work?
When someone has sex with an HIV patient or gets a needlestick injury potentially contaminated with HIV
4 wk course of pills that reduces risk by 60-70%
How does HIV affect work?
Some jobs require an HIV test but otherwise you dont need to tell them
Recently its been decided patients who do jobs that risk transmission e.g. surgeon can still work if they have an undetectable viral load
How do we treat HIV?
Combination Anti-retroviral Therapy (cART)
3 drugs from atleast 2classes in 1 combined daily pill
Can give a full length normal life though may have severe complications like lipodystrophy
When do we start a patient on cART?
At diagnosis if possible, life expectancy is relative to their CD4 count at onset of therapy.
Otherwise they need to start at CD4 of 350 to prevent AIDS.
