HIV Flashcards
Describe HIV structure
ssRNA retrovirus
How can HIV be transmitted?
- unprotected sex
- vertical transmission
- infection of HIV positive bodily fluids e.g. needle sharing, blood splashed in an eye
How can you prevent HIV transmission during birth?
Dependent on the mother’s viral load:
- <50copies/ml: normal vaginal delivery
- >50copies/ml: consider pre-labour C section
- over 400copies/ml: pre-labour C section recommended.
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- IV zidovudine given during labour + delivery if viral load is unknown or >1000copies/ml
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- prophylaxis for the baby: zidovudaine, lamivudine + nevirapine for 4 weeks
What are the two forms of prophylaxis for HIV?
- PrEP: truvada (emtricitabine/tenofovir)
- PEP: truvada (emtricitabine/tenofovir) and raltegravir for 28 days
How does HIV infect the cell?
- infects with CD4 surface receptor
- replicates inside the cell > kills the cell > inflammation > infects more cells
Symptoms of HIV
- fever
- weigh loss
- malaise
- headache
- thrush
- rash
- N+V
- sores in mouth
Diagnosis of HIV
- nucleic acid test (PCR)
- antigen/antibody test (serology)
- antibody rapid tests
When do AIDs defining illnesses occur?
when CD4 count drops <200 which allows for opportunistic infections + malignancies to occur
Examples of AIDs defining illnesses
- pneumocystis jirovecii pneumonia PCP (most common)
- TB
- Kaposi’s sarcoma
- candidiasis
- lymphomas
- cytomegalovirus infection
What do patients with a CD4+ count of <200 need + why?
co-trimoxazole OD as primary prophylaxis for PCP
What do patients with a CD4+ count of <50 need + why?
- azithromycin once weekly to protect against mycobacterium avium-intracelluare infection
- ophthalmology assessment with dilated fundoscopy to look for evidence of intra-ocular infections
Baseline investigations for all patients with newly diagnosed HIV
- confirmatory HIV test
- CD4 count + viral load
- HIV resistance profile
- HLA B*5701 status
- serology for syphilis, hep A/B/C
- IgG for measles, varicella, rubella + toxoplasma
- FBCs, U&Es, LFTs, bone + lipid profile
- annual cervical cytology for women
Monitoring of HIV
_CD4 count_
- normal: 500-1200 cells/mm^3
- risk of AIDs defining illnesses: <200cells/mm3
.
_viral load_
- testing for HIV RNA per ml of blood
- undetectable: 20 copies/ml
Treatment of HIV
combination antiretroviral therapy offered irrespective of viral load or CD4 count:
two nucleoside reverse transcriptase inhibitors e.g. truvada (tenofovir + emtrictabine) + a 3rd agent e.g. bictegravir
Aims of HIV treatment
normal CD4 count (500-1200)
undetectable viral load (<20)
What vaccinations should someone with HIV have?
- hepatitis B
- pneumoccous
- flu
- avoid live vaccines e.g. BCG
Monitoring of CD4 in HIV
- 500-1200 cells/mm3 - normal
- <200 cells/mm3 > patient is at high risk of opportunistic infections
Additional management of HIV (on top of antiretroviral therapy)
- prophylactic co-trimoxazole: if CD4 <200 to protect against pneumocystis jirovecii pneumonia
- close monitoring of CVD risk factors due to increased risk
- yearly cervical smears due to increased HPV + cervical cancer risk
- vaccinations - avoid live vaccines
- condom use
General side effect of NRTIs
Peripheral neuropathy
Features f pneumocystis jiroveci pneumonia
- dyspnoea
- dry cough
- fever
- minimal chest signs on examination
Chest x ray in pneumocystis jiroveci pneumonia
Bilateral interstitial pulmonary infiltrates
Management of pneumocystis jiroveci pneumonia
Co trimoxazole
Steroids if hypoxic
Ways to reduce vertical transmission of HIV
- maternal antiretroviral therapy
- C section
- neonatal antiretroviral therapy
- bottle feeding
