HIV Flashcards
What is the difference between HIV / AIDS?
HIV:
- having contracted the human immunodeficiency virus
AIDS:
- HIV progresses and the person becomes immunodeficient
- they are susceptible to opportunistic infections
- now referred to as late-stage HIV
(acquired immunodeficiency syndrome)
What is HIV and how does it cause illness?
- it is a RNA retrovirus
- the virus enters and destroys CD4 T-helper cells of the immune system
- reverse transcriptase integrates HIV DNA into host DNA, which takes 3-5 days after exposure
- HIV virions budding out will destroy the host T cell
How does HIV typically present?
- there is an initial seroconversion flu-like illness within a few weeks of infection (primary HIV)
- the person is then asymptomatic until the condition progresses to immunodeficiency
- immunodeficient patients develop AIDS-defining illnesses** + **opportunistic infections
- this progression can take several years
Why does it take several years for HIV to progress to immunodeficiency?
- the CD4 cells are destroyed faster than they are being made
- it takes time for the CD4 count to become so low that immunodeficiency results
How can HIV be transmitted?
- unprotected anal, vaginal or oral sexual activity
- mother to child at any stage of pregnancy, birth or breastfeeding (vertical transmission)
- mucous membrane, blood or open wound exposure to infected blood or bodily fluids
- e.g. sharing needles, blood splashed in an eye
What type of sex is associated with an increased risk of HIV transmission?
- receptive anal intercourse is the highest risk, followed by:
- receptive vaginal intercourse
- insertive anal intercourse
- insertive vaginal intercourse (lowest risk)
What other sexual factors can increase the risk of HIV transmission?
- trauma (e.g. sexual assault / fisting) that damages the skin
- presence of other STIs / genital infections
- e.g. HSV, gonorrhoea, syphilis, BV
What is the risk of contracting HIV from oral sex?
- the likelihood of transmission is rare, but it is possible
- the person who is receiving is at greater risk
- dental treatment / bleeding gums / ulcerative conditions increase the risk
!! HIV cannot be transmitted through saliva !!
(i.e. kissing / sharing cups)
What is involved in the natural history of HIV?
- there is a sharp drop in CD4 count shortly after primary infection
- opportunistic infections may arise at this point
- CD4 count then comes back up and stays steady for some time
- it then gradually declines as HIV viral load increases
- this is when symptoms start to develop
What are the typical symptoms of primary HIV infection (seroconversion)?
- symptoms begin 2-6 weeks** after infection and last for **5-10 days
- fever
- pharyngitis
- lymphadenopathy
- skin rash
- myalgia
- headache / malaise
- N&V
!! a recent negative HIV test supports the diagnosis !!
Why would a HIV test be negative during primary infection?
- it can take up to 3 months for antibodies against HIV to be made
- p24 antigen may be positive at this stage, but antibodies will be negative
How can someone tell they are in the asymptomatic stage of HIV infection?
Why is it important to detect this?
- the only way to tell is by doing a blood test for HIV
- there is ongoing viral replication causing immune system damage during this stage
- this chronic inflammatory state increases the risk of malignancy + cardiovascular disease
What symptoms may develop when someone enters the symptomatic stage of HIV infection?
skin lesions:
- folliculitis
- multi-site herpes zoster
- seborrhoeic dermatitis
oral lesions:
- candidiasis
- oral hairy leukopenia
recurrent bacterial infections:
- pneumonia
- impetigo
abnormal blood results:
- lymphopenia
- thrombocytopenia
non-specific symptoms:
- diarrhoea
- fever
- myalgia
- persistent lymphadenopathy
When do AIDS-defining illnesses occur?
- these are associated with end-stage HIV infection
- the CD4 count has become so low that opportunistic infections / malignancies can occur
Why are there worse outcomes associated with diagnosis at a late stage?
- the lower the CD4 count, the greater the damage to the immune system
- there is less chance of immune system recovery
What are examples of AIDS-defining illnesses?
- Kaposi’s sarcoma
- pneumocystis jirovecii pneumonia
- cytomegalovirus infection
- candidiasis (oesophageal / bronchial)
- lymphomas
- tuberculosis
What is the drawback of HIV testing using HIV antibodies?
- it can take up to 3 months to develop antibodies to the virus
- HIV antibody tests can be negative for 3 months following exposure
- a repeat test is required within 3 months if the initial test is negative
What test can detect HIV earlier than the antibody test?
testing for the p24 antigen:
- this is a antigen specific to HIV
- it can given a positive result earlier in infection than the antibody blood test
What 2 tests are used in the monitoring of HIV?
- CD4 count
- viral load (VL)
What is the CD4 count and why is it monitored?
- the number of CD4 cells in the blood
- this is an indicator of the risk of opportunistic infections
- CD4 count usually improves with treatment
What is a normal CD4 count?
When is someone at greater risk of opportunistic infections?
normal range:
- 500 - 1,200 cells / mm3
- there is no need to monitor regularly if > 350 cells / mm3
end-stage HIV:
- < 200 cells / mm3
- the patient is at a high risk of opportunistic infections
What does viral load measure?
- it is the number of copies of HIV RNA per ml of blood
- it is monitored to assess disease progression +/- treatment response
What is a normal viral load?
- “undetectable” refers to a viral load below the detectable range
- this is usually 50 - 100 copies / ml
- the aim of treatment is to get viral load < 50 copies / ml
What is the typical treatment regime for HIV?
- highly active antiretroviral therapy (HAART / ART) is used
- this is usually 3 different drugs in combination
- treatment is lifelong
- compliance is essential as viral replication under partial pressure can result in drug resistance
What is the aim of HIV treatment?
to achieve a normal CD4 count and undetectable viral load
What additional prophylaxis is given to patients with a CD4 count < 200?
prophylactic co-trimoxazole
- this is to protect against pneumocystis jirovecii pneumonia
What is significant about HIV and cardiovascular risk?
- HIV increases the risk of developing cardiovascular disease
- close monitoring of blood lipids / risk factors is required
- statins may be started to reduce CVD risk
How is cervical screening different for patients with HIV?
- they are offered yearly smear tests
- HIV predisposes to HPV infection and cervical cancer
What is important about vaccinations in a HIV positive patient?
ALL vaccinations should be up to date:
- influenza
- pneumococcal
- hepatitis A + B
- tetanus
- diphtheria
- polio
!! patients should AVOID live vaccines !!
What advice is given around sexual intercourse and HIV?
- condoms are advised for all acts of sexual intercourse
- transmission is almost unheard of when the viral load is undetectable, but still possible
- partners should have regular HIV tests
- unprotected sex / pregnancy** are considered when **viral load is undetectable
When is a normal vaginal delivery recommended?
for all women with a viral load < 50 copies / ml
When is Caesarean section recommended?
What medication may be given during the procedure?
- considered when viral load > 50 copies / ml
- highly recommended when viral load > 400 copies / ml
- IV zidovudine is given if viral load is unknown or there are > 10,000 copies per ml
What prophylactic treatment is given to low-risk babies?
- when mother’s viral load < 50 copies / ml
- zidovudine** is given for **4 weeks
What prophylactic treatment is given to high risk babies?
- when mother’s viral load > 50 copies per ml
- zidovudine, lamivudine + nevirapine are given for 4 weeks
What is the recommendation for breastfeeding?
- HIV can be transmitted during breastfeeding, even when the viral load is undetectable
!! breast feeding is not recommended !!
- it is sometimes attempted with close monitoring if mother is very keen and viral load is undetectable
What is the rapid point of care test for HIV?
- self administered blood test with an immediate result
- if the test is positive, a blood test is required for confirmation
When sending a venous blood sample to the lab to test for HIV, what must always be done as follow-up?
- a second confirmatory sample should be sent to ensure no labelling / lab process error
- action is taken based on first result
What are the guidelines around telling other people following a new HIV diagnosis?
- encourage the patient to tell their contacts (but this cannot be enforced)
- anonymous provider referral is available
- failure to disclose can result in criminal proceedings if the transmission was preventable
What is pre-exposure prophylaxis (PrEP) and who may used this?
- taken by HIV-negative people before, during and after sex
- 2 tablets are taken 2-24 hours before sexual activity
- it can be taken daily or around sexual activities
- it prevents HIV contraction but does not protect against other STIs
- regular testing is required
What is post-exposure prophylaxis (PEP)?
When is it taken?
- HIV medications that are taken after high risk sex / exposure
- medication taken for 28 days
- should be started as soon as possible, but can be taken up to 72 hours after exposure
What is the current PEP regime?
- Truvada (emtricitabine + tenofovir)
AND
- raltegavir
taken for 28 days
When must HIV tests be performed in someone taking PEP?
- perform a HIV test immediately and after 3 months to confirm a negative status
- individuals should abstain from sexual activity for 3 months
