23 - HIV Flashcards
What is the pathogenesis of HIV?
HIV 1 (most common) and HIV2 (West Africa)
- Fusion: using CD4 receptor and co-receptor CCR5
- Reverse Transcriptase: make DNA from viral RNA
- Integrase: viral DNA into host DNA
- Protease: for protein processing
- Budding and Maturation
How is HIV transmitted?
- Unprotected oral, vaginal, anal sex
- Vertical Transmission during birth
- Blood in eye
- Contaminated needles
- Blood products that are infected
What groups of people are at an increased risk of contracting HIV?
- Men who have sex with men (MSM)
- Female sexual contacts of MSM
- Trans women
- Black Africans
- Those from a country with high diagnosed seroprevalence
- Those with sexual contact with anyone from a country with high seroprevalence
- Those with a mother with HIV who have not themselves been tested
- Those who use injectable drugs
- Sex workers
- Prisoners
What are the three stages of HIV if left untreated?
- Acute seroconversion: Occurs 1-6 weeks after infection as antibodies being made. Can be flu-like/mono symptoms like muscle aches, fever, sore throat, mouth ulcers, diarrhoea. Can also be asymptomatic
2. Chronic Infection: After around 6 months, stable viral loud, CD4 count starts to drop. Lasts about 8-10 years
3. Late Stage/AIDS: CD4 below 200. Lots of opportunistic infections and malignancies. Average survival of 12-20 months
What are some examples of AIDS defining illnesses?
Who should be tested for HIV?
- MSM
- Pregnant
- TOP
- TB
- People living in areas of high prevalence of HIV
- AIDS defining illnesses
How is HIV tested for and when?
Can take up to three months to develop antibodies so do one at 4 weeks and one at 3 months as 4 weeks might be false negative
- Point of Care Test/Self Sampling: Looks for antibody, can show 21-24 days after exposure. Rapid so good if pt doesn’t want to leave contact details, need to explain if positive will need serological confirmation. Also if negative but <3 months will need a repeat
- Serological blood test: PCR for HIV RNA, HIV p24 antigen and HIV antibody. Takes 45 days to show, earlier for antigen
Once a patient has a HIV positive diagnosis, what other investigations need to be done?
- HIV-1/HIV-2 differentiation immunoassay
- Viral load
- CD4+ T cell count (above 500 is normal)
- Viral hepatitis serology
- Full STI screen (including syphilis serology)
Offer women cervical cytology yearly!
What classifications of medicine are there in Highly Active Anti-Retrovirus Therapy Medication (HAART)?
- Protease Inhibitors
- Integrase Inhibitors
- Nucleoside Reverse Transcriptase Inhibitors
- Non Nucleoside Reverse Transcriptase Inhibitors
- Entry Inhibitors
- CCR5 Inhibitors e.g Maraviroc
- Fusion Inhibitors
What is the typical HAART regime for HIV and when do you start patients on this?
Start them as soon as diagnosed regardless of viral load and CD4 count. Aim is to make viral load undetectable and keep CD4 high
- Two NRTIs (tenofovir and emtricitabine)
PLUS
- Third agent (PI, II, NNRTI)
How is HIV monitored after starting HAART?
- Viral Load: repeat every 6-12 months after suppression achieved
- CD4 Count: If >350 twice in one year then routine monitoring not needed
What is the prognosis with HIV?
If detected early, CD4>350 and viral load undetectable then can have normal life expectancy
If AIDS (CD4<200) then 12-20 months average
Apart from HAART, what extra medications/regular investigations do HIV patients need?
NB CARD
- Statins: high risk of developing CVD so monitor lipids
- Yearly cervical smears: more risk of HPV
- Vaccinations: Flu, Pneumococcal, Hep A/B, Tetanus all need to be up to date but AVOID live vaccines
- CD4<200: Need prophylactic co-trimoxazole against PCP
What advice should you give a HIV positive patient about conceiving?
- Advise condoms and dams even when both partners positive
- Regular HIV tests for partner
- Can have sperm washing and IVF
- If viral load undetectable can have unprotected sex at time of ovulation safely as unheard of if low viral load to pass on
How can transmission of HIV be prevented during birth?
- Mode of delivery depends on viral load of mother
- Prophylaxis to Baby: If viral load <50 then Zidovudine for 4/52 to baby. If viral load >50 give Zidovudine, Lamivudine and Nevirapine for 4/52
- Avoid breastfeeding even if viral load undetectable
What are the side effects of these classifications of HAART?
- NRTIs
- Tenovir: Renal Failure and Osteoporosis
- Lamivudine: Pancreatitis
- Abacavir: Avoid in CVD
- Emtricitabine: Hyperpigmention of palms and soles
What are the side effects of these classifications of HAART?
NNRTIs
- Resistance
- CNS disturbance
- QT prolongation
- Drug induced hepatitis
What are the side effects of these classifications of HAART?
Protease inhibitors
Good for resistant strains
- Lipodystrophy
- Hyperlipidaemia
- Insulin resistance
- Hepatotoxicity
What investigations should you do if you suspect PCP in a HIV patient and what will these investigations show?
- CXR: bilateral bihilar interstitial infiltrates
- High resolution CT: If above nil then do these for cysts and nodules
- Bronchoscopy associated with bronchoalveolar lavage: Use Grocott’s stain and will show ‘mexican hat’ appearance. DIAGNOSTIC
How is PCP managed?
Co-trimoxazole - regardless of severity
What is PEP and what is the regime with this?
Post Exposure Prophylaxis when risk of HIV exposure, must be given within 72 hours of exposure
Raltegravir (Tenofovir) and Truvada (Emtricitabine)
Given for 28 days
Test for HIV immediately and then in 3 months, abstaining from unprotected sex until they know they are negative
What drugs are included in PrEP and when is it taken?
Tenofovir Disoproxil / Emtricitabine (TD-FTC)
Can either take daily tablet or on demand
Who should be offered PrEP and what regime should they use?
MSM (either regime)
- HIV-negative MSM had condomless anal sex in the previous 6 months and ongoing condomless anal sex
- HIV-negative MSM having condomless anal sex with partners who are HIV positive, unless partner has been on ART for at least 6 months and their plasma viral load is <200 copies/mL
Heterosexual (daily)
- HIV-negative heterosexual men and women having condomless sex with partners who are HIV positive, unless the partner has been on ART for at least 6 months and their plasma viral load is <200 copies/mL
Trans (daily)
- Same as above, if condomless anal or HIV positive partner who has been on ART <6 months
IVDU
- Needle exchange programmes only
