HIV Flashcards
What does HIV stand for?
Human Immunodeficiency Virus
What is the structure of HIV?
SsRNA with envelope
HIV is a retrovirus, What is meant by retrovirus?
Is turns ssRNA into DNA and back again
What cells will HIV infect?
Cells with a CD4 surface receptor:
T helper lymphocytes
(Monocytes/macrophages)
How does HIV infect a cell?
- Binds to CD4 and other receptors on cell
- Inserts contents
- Reverse transcriptase turns the ssRNA from the virus into DNA
- Viral DNA is integrated into cells DNA by integrase enzyme (which is why it is so hard to treat)
- When infected cells divide, viral DNa is read and long chains of proteins are made
- Protein buds off and forms new virus (proteases create mature virus)
How is HIV transmitted?
Contact of infected bodily fluids with mucosal tissue/blood/broken skin
Ie sexual contact, transfusions (other medical procedures: skin grafts,organ donation), contaminated needles, perinatal transmission (during delivery through infected birth canal or result of ingestion of breast milk carrying virus)
What are the 4 stages of HIV infection?
- Primary infection/seroconversion (very infectious)
- Latent infection (CD4 count in much larger than viral load)
- Symptomatic infection (point at which viral load is greater than Cd4 count) ~350 - point at which people will notice they are unwell
- Severe infection/AIDS ~ <200 - at risk of severe infections/cancer/AIDS
What are the main symptoms and signs that are associated with an acute HIV infection?
Systemic:
Fever, weight loss
Mouth: sores, thrush
Oesophagus: sores
Muscles: myalgia
Liver and spleen: enlargement
Central: malaise, headache, neuropathy
Lymph nodes: lymphadenopathy
Skin: rash
Gastric: nausea, vomiting
Pharyngitis
Anaemia
Give examples of conditions associated with severe HIV
Brain: AIDS dementia complex
Eyes: CMV
Mouth: thrush
Blood: hyperglycaemia
Bones: osteoporosis
Heart: heart disease, stroke
Liver: Hep C
What does a low viral load in the blood mean in terms of HIV transmission?
Transmission is unlikely if undetectable VL
How can someone with HIV live a normal length life?
Early detection
Treatment
Adherence
Healthy living (smoking, alcohol, metabolic problems)
*the later the detection = worse prognosis
**the higher the CD4 count is when diagnosis is made the Better the chances of increases those levels
What blood tests would you do when confirming HIV?
Serology (looking at Ag and Ab)
PCR (detects HIV nuclei acid)
‘Rapid’ tests
How accurate is the serology blood test at diagnosing HIV?
Can detect both Ag and Ab within 4 weeks
Results can be given on the same day
*may get a false negative if test is performed too early
What are the pros and cons to doing a PCR blood test on someone with HIV?
Highly sensitive, detects very early infection (few days)
Expensive, results are slow
**this is used for follow up/treatment response not for initial HIV testing
What is a “rapid’ test for HIV?
Portable test for diagnosing HIV
Usually detect HIV antibody
Can be a finger print (blood) or oral (saliva) test
They have very accurate negative readings but it can give false positive results - would need to confirm result with serology
Who should be tested for HIV?
Everyone who presents with unexplainable symptoms ie pneumonia/ TB/ meningitis/ dementia/ weight loss/ blood abnormality / any STI etc
People with conditions known to have an association; lymphoma, anal cancer
What are the aims of HIV treatment? (6)
Undetectable HIV VL (not enough just to lower the viral lode) Reconstituted CD4 count/ immune system Reduce general inflammation Reduce risk of transmission Good quality of life Normalise lifespan
What is used to treat HIV?
ARV drugs
Anti-retro viral drugs
At what stages within the HIV’s infection mechanism would you target drugs?
- Binding and fusion stage
- Reverse transcription stage
- Integration into cells DNA stage
- Maturation of budded virus stage
When should someone be started on ARV drugs to treat HIV?
Straight away- regardless of CD4 count
Which ARVs are given to treat HIV?
Combination of:
Nucleoside reverse transcriptase inhibitor (NRTI)
AND
Nuceloside reverse transcriptase inhibitor (NRTI)
AND (one of the following)
Non-nucleoside reverse transcriptase inhibitors (NNRTI)
Protease inhibitor
Integrate inhibitor
CCR5 (entry) inhibitor
Why are 3 ARVs given at once to treat HIV?
Because HIV is very prone to mutation and it is harder to develop resistance against 3 drugs
**it is vital that the patient keeps taking their drugs
What strategies can be used to treat and reduce the prevalence of HIV?
- increase condom use
- prevention of mother-to-child transmission (c-section, no breast feeding)
- ARV treatment as prevention (stops onwards transmission)
- medical circumcision
- PEP- post exposure prophylaxis
- PrEP- pre exposure prophylaxis (someone who is likely to have a potential exposure to HIV)
How might someone have immunity to HIV?
If they are lacking necessary proteins/ receptors on their cells so the HIV cannot enter the cell
What are the ethical dilemmas that can be associated with HIV?
-psychological impact of diagnosis
-dealing with stigma
-patient confidentially vs:
Health of patient
Health of unborn child
Health of sexual partners
Health of older children
Risk to patients/staff at workplace
Which initial investigation would you request from someone you susceptible of having HIV?
Full blood count- Hb levels, white blood cells CRP- looking for inflammatory markers UandEs LFT HIV tests (Serology and PCR) CD4 count
chest x ray and head scan etc depending on other presenting symptoms
