HIV Flashcards
Kaposis sarcoma
Caused by HHV-8 infection in HIV positive individuals AIDS defining illness. Multiple purplish nodules in the skin
CD4 count 200 - 500 cells/mm³
- Oral thrush –> Secondary to Candida albicans
- Shingles -> Secondary to herpes zoster
- Hairy leukoplakia -> Secondary to EBV
- Kaposi sarcoma -> Secondary to HHV-8
CD4 count 100 - 200 cells/mm³
- Cryptosporidiosis
- Cerebral toxoplasmosis
- Progressive multifocal leukoencephalopathy -> Secondary to the JC virus
- PJP
- HIV dementia
CD4 count 50 - 100 cells/mm³
- Aspergillosis -> Secondary to A.fumigatus
- Oesophageal candidiasis ->Secondary to Candida albicans
- Cryptococcal meningitis
- Primary CNS lymphoma ->Secondary to EBV
CD4 count < 50 cells/mm³
- Cytomegalovirus retinitis -> Affects around 30-40% of patients with CD4 < 50 cells/mm³
- Mycobacterium avium-intracellulare infection
HIV, neuro symptoms, widespread demyelination
Progressive multifocal leukoencephalopathy. Caused from JC virus:
- widespread demyelination due to infection of oligodendrocytes by JC virus (a polyoma DNA virus)
- Symptoms, subacute onset -> behavioural changes, speech, motor, visual impairment
- CT: single or multiple lesions, no mass effect, don’t usually enhance.
- MRI is better - high-signal demyelinating white matter lesions are seen
HIV: neurocomplications
Focal neurological lesions:
- Toxoplasmosis - 50% of cerebral lesions
- Primary CNS lymphoma - 30% of cerebral lesions assoc with EBV
- TB - much less common than above. single enhancing lesion on CT
Generalised neurological disease:
- encephalitis
- cryptococcus
- progressive multifocal leukoencephalopathy - AIDS dementia complex
Toxoplasmosis
- accounts for around 50% of cerebral lesions in patients with HIV.
- CT: MULTIPLE lesions with ring or nodular enhancement.
- SPECT negative Constitutional symptoms, headache, confusion + drowsiness.
- management: sulfadiazine and pyrimethamine
Primary CNS lymphoma
- Assoc with EBV
- CT: SINGLE lesion (or multiple) homogenous aka solid enhancing lesions.
- Thallium SPECT positive treatment generally involves steroids (may significantly reduce tumour size), chemotherapy +/- whole brain irradiation.
- Surgical may be considered for lower grade tumours
HIV drugs rule of thumb
- NRTIs end in ‘ine’
- Pis: end in ‘vir’
- NNRTIs: nevirapine, efavirenz
Highly active anti-retroviral therapy (HAART)
At least 3 drugs - typically 2 NRTI and either a PI or a NNRTI
Entry inhibitors
- maraviroc (binds to CCR5, preventing an interaction with gp41),
- enfuvirtide (binds to gp41, also known as a ‘fusion inhibitor’) prevent HIV-1 from entering and infecting immune cells
Nucleoside analogue reverse transcriptase inhibitors (NRTI)
- examples: zidovudine (AZT), abacavir, emtricitabine, didanosine, lamivudine, stavudine, zalcitabine, tenofovir
- general NRTI side-effects:
- peripheral neuropathy
- tenofovir: used in BHIVAs two recommended regime NRTI. Adverse effects include renal impairment and ostesoporosis
- zidovudine: anaemia, myopathy, black nails
- didanosine: pancreatitis
Non-nucleoside reverse transcriptase inhibitors (NNRTI)
- examples: nevirapine, efavirenz
- side-effects: P450 enzyme interaction (nevirapine induces), rashes
Protease inhibitors (PI)
- examples: indinavir, nelfinavir, ritonavir, saquinavir
- side-effects: diabetes, hyperlipidaemia, buffalo hump, central obesity, P450 enzyme inhibition
- indinavir: renal stones, asymptomatic hyperbilirubinaemia
- ritonavir: a potent inhibitor of the P450 system
Integrase inhibitors
- raltegravir, elvitegravir, dolutegravir
Immune reconstitution inflammatory syndrome
- can occur in HIV positive patients when starting anti-retrovirals; this is an immune phenomenon that results in the clinical worsening of a pre-exisiting opportunistic infection.
- TB is the most common cause of IRIS
HIV seroconversion
- HIV seroconversion is symptomatic in 60-80% of patients and typically presents as a glandular fever type illness.
- Increased symptomatic severity is associated with poorer long term prognosis. It typically occurs 3-12 weeks after infection.
- Features: sore throat, lymphadenopathy malaise, myalgia, arthralgia, diarrhoea maculopapular rash mouth ulcers, rarely meningoencephalitis
- Dx: antibodies to HIV may not be present HIV PCR and p24 antigen tests can confirm diagnosis
Pregnancy
Factors which reduce vertical transmission (from 25-30% to 2%)
- maternal antiretroviral therapy
- mode of delivery (caesarean section)
- neonatal antiretroviral therapy
- infant feeding (bottle feeding)
Antiretroviral therapy
- all pregnant women should be offered antiretroviral therapy regardless of whether they were taking it previously
Mode of delivery
- vaginal delivery is recommended if viral load is less than 50 copies/ml at 36 weeks, otherwise caesarian section is recommended a zidovudine infusion should be started four hours before beginning the caesarean section
- Neonatal antiretroviral therapy zidovudine is usually administered orally to the neonate if maternal viral load is <50 copies/ml. Otherwise triple ART should be used. Therapy should be continued for 4-6 weeks. Infant feeding in the UK all women should be advised not to breast feed
Pneumocystis jiroveci
- unicellular eukaryote, generally classified as a fungus but some authorities consider it a protozoa
- PCP is the most common opportunistic infection in AIDS
- all patients with a CD4 count < 200/mm³ should receive PCP prophylaxis
- Extrapulmonary manifestations are rare (1-2% of cases), may cause hepatosplenomegaly lymphadenopathy choroid lesions
-
Ix:
- CXR: typically shows bilateral interstitial pulmonary infiltrates but can present with other x-ray findings e.g. lobar consolidation. May be normal exercise-induced desaturation sputum often fails to show PCP,
- BAL often needed to demonstrate PCP (silver stain shows characteristic cysts)
- Mx:
- co-trimoxazole IV pentamidine in severe cases aerosolized pentamidine is an alternative treatment for Pneumocystis jiroveci pneumonia but is less effective with a risk of pneumothorax steroids if hypoxic (if pO2 < 9.3kPa then steroids reduce risk of respiratory failure by 50% and death by a third)
Cancers associated with HIV
Delta32 mutation in CCR5
Conveys resistance to HIV1 in homozygous patients
Toxoplasma Encephalitis
Side effects of HIV-PIs
- increased chlesterol and triglyceride concentrations, assoc with insulin resistance and DM
- Also assoc with an increased risk of MI
- hepatotoxicity and rash
Side Effects of CCR5 antagonists
rash
hepatotoxicity
Fiebig Stages of HIV
Fiebig Stages I to VI
I - Viral RNA PCR positive (first positive study)
Side Effects of Fusion Inhibitors (Anti-retrovirals)
Side Effects of NNRTIs
PrEP for HIV regimen
Tenofovir (disoproxil fumarate) and Emtricitabine
PBS streamline authority
- Adult patients who are HIV negative
- Who are high risk of contracting HIV
- Before starting PrEP
- Test for HIV
- Check renal function eGFR > 60
- Check for other STIs and give vaccines
