HIV/AIDS Flashcards
Number of people with HIV globally?
~35 million
Gender distribution HIV?
Roughly 50%
Why is number of people with HIV increasing?
Longer lifespan post diagnosis due to new treatment strategies
Hx features ?HIV history?
- male or female sex
- anal or vaginal sex without condomes
- partners from poorer countries
- partners commercial sex workers
- IVDU or steroids?
Determining transmission risk for HIV?
Risk of HIV transmission = risk per exposure x risk of source being HIV positive
Second part based on HIV seroprevalence in community group.
Factors increasing risk of HIV transmission?
- Damage to mucosal membranes (abrasion, ulcer etc)
- High viral load
- Direct injection with a needle containing HIV infected blood
- Sexually transmissible infection in the source or exposed individual (esp genital ulcers, symptomatic gonococcal infections)
HIV transmission biology?
- HIV envelope protein (GP120) binds CD4 on M0 with CCR5 costimulation
- CD4 molecule with CXCR4 costimulation (less efficient)
- HIV internalised to M0
- Spread to LNs –> blood –> widespread dissemination (brain, spleen, lymphoid tissue)
- Reservoir - latency
Ix in ?HIV?
- Serology: syphilis, HIV, hepatitis A/B/C (if appropriate)
- Swab of penile ulcer for HSV PCR
- Consider: anal swab for PCR for HSV, N. gonorrhoea, Chlamydia trachomatis
- Throat swab for N. gonorrhoea PCR
- First pass urine for C. trachomatis, gonorrhoea
What should you tell pt pre HIV testing?
- Limited consent: tell doing test
- Screening test: need confirmation i.e. if +ve, will require further testing
- Window period: tests detect Ab i.e. period between exposure and positive result
What tests are used for HIV detection?
-4TH GEN COMBO: Ig HIV Ab and p24 Ag: sens/spec >99%; may be used to exclude HIV.
-RAPID TESTS/PoCT: used for screening for HIV (i.e. not to exclude HIV); based on either Ab/Ag
Both require confirmation with further test -> usually Western blot; alternatives NAAT.
Key points to communicate at new HIV diagnosis?
- HIV NOT AIDS
- HIV readily treatable with only moderately increased risk of some diseases
- Regular medical checks
- Use condoms; r/v safe sexual practices later also
Reasons for continuing increased mortality in HIV?
- Persistent inflammation and immune dysfunction
- More comorbidities: smoking, HTN, DM
- Recreational drug use
- Antiretroviral toxicity
Key questions to ask Luke at Dx?
- Have you donated blood / semen in past year?
- Are any sexual partners from last year contactable?
- Who can you talk to for support?
- Discuss symptoms of seroconversion illness; may give indication as to duration of illness.
What is seroconversion illness?
- Converting from HIV Ab -ve to +ve
- 3-5 weeks post transmission
- Fever, sore throat, rash, diarrhoea, weight loss
- Often very high levels of plasma viral RNA
- Good description suggests infection occurred about a month previously
What are the classical HIV opportunistic infections?
- cerebral toxoplasmosis
- pneumocystic jiroveccii pneumonia
- CMV retinitis
