HIV/AIDS Flashcards
What is HAART?
Highly active anti-retroviral therapy
What are the units of viral load?
RNA copies/ml
What are the aims for viral load with treatment?
To be undetectable < 50 cpm bc lower viral load means less transmission
What does the CD4 count show and determine?
- It shows the degree of immune damage
- It determines when to start anti-retroviral therapy
What is the natural course of of HIV/AIDS over 5-20 years?
1) Acute infection and seroconversion
2) Asymptomatic (transmission occurs)
3) HIV related illness e.g. weight loss, night sweats
4) AIDS defining illness
5) Death
What is a normal CD4 count?
> 350
At what CD4 count do most AIDS diagnoses occur?
< 200
What is seroconversion?
When the body makes antibodies against the virus
How does the virus enter CD4 cells?
Via CD4 receptors
How can you reduce perinatal HIV transmission?
- Early HIV diagnosis
- Treatment for mother to reduce viral load
- Appropriate delivery method
- Avoid breastfeeding
What prophylaxis treatment can be given for HIV?
PrEP (pre-exposure prophylaxis)
What are clinical features of primary HIV infection (acute seroconversion)?
- Fever, rash, sore throat
- Glandular fever-like illness
- Lymphadenopathy
- Malaise, myalgia, arthralgia, diarrhoea
- Neurological symptoms e.g. meningitis, encephalitis, neuropathy, myelopathy
- Ulceration (oral, ano-genital)
Does everyone with primary HIV infection have symptoms and why?
No, viral replication rate may be slow or CD4 count is steady or falls slowly
What are viral differential diagnoses of HIV seroconversion?
- Infectious mononucleosis
- CMV
- Rubella
- HSV
- Adenovirus
- Hep B/C
- Flu
What are bacterial differential diagnoses of HIV seroconversion?
- Secondary syphilis
- Streptococcal pharyngitis
What are protozoal differential diagnoses of HIV seroconversion?
Toxoplasmosis
What are neoplastic differential diagnoses of HIV seroconversion?
- Lymphoma
- Leukaemia
What are 4 basic ‘non-specific’ HIV related symptoms?
1) Fevers
2) Night sweats
3) Weight loss
4) Diarrhoea
What else might happen in symptomatic HIV disease?
Simple conditions e.g. skin conditions, chest infections, HSV become recurrent or harder to treat
What are examples of AIDS defining illnesses where there is advanced disease with severe immunosuppression?
- Candidiasis
- Cervical cancer
- CMV
- Kaposi’s sarcoma
- Lymphoma
- TB
- PCP (pneumocystis jiroveci) pneumonia
- Cerebral toxoplasmosis
- Mycobacterium avium complex
- PML
- Cryptococcosis
What would a CXR look like in PCP pneumonia?
Lots of white shading everywhere, foggy
What might you see in a head scan in toxoplasmosis?
Abscess
How is PrEP used?
It is taken by someone when they might do something that would put them at risk of HIV
What are differentials of HIV + cough?
- Bacterial (pneumococcus) pneumonia
- TB
- PJP
- Other causes rare
What CD4 counts would indicate unlikely PJP?
CD4 > 200 OR CD4 < 200 but taking prophylaxis
What investigations would you do for suspected pneumonia?
- History and examination
- CXR
- Arterial sats
- Exercise oximetry (5 mins)
- Induced sputum ± bronchoalveolar lavage
- Consider CT-CAP
- Screen for TB
What is a typical presentation of PJP?
- Gradual onset (weeks)
- Fever, dyspnoea, cough, chest discomfort
- Desaturation on exercise
- CXR can be normal, or interstitial infiltrates, nodular lesions, PTX or pleural disease
- Hypoxia
- LDH elevated
What is the first choice treatment in PJP that can also be used for prophylaxis?
Co-trimoxazole
What is TB-IRIS?
TB-immune reconstitution inflammatory syndrome - occurs in HIV patients
What CNS diseases can occur in HIV?
- Cerebral toxoplasmosis
- HIV encephalitis
- HIV neurocognitive disorder (HAND)
- Primary cerebral lymphoma
- Cryptococcal meningitis
- PML
- Syphilis
What are symptoms of CNS diseases in HIV?
- Headache
- Seizure
- Focal signs
- Altered consciousness/confusion
- Signs of meningism
- Fever
What is first line treatment for toxoplasmosis?
Sulphadiazine or clindamycin + pyrimethamine + folinic acid
How do you manage cryptococcal meningitis?
- Exclude pulmonary infection
- Test for serum cryptococcal antigen
- Blood cultures
- CSF incl. opening pressure
- Treat with IV amphotericin (ambisome) and flucytosine following by fluconazole
What are late complications of cryptococcal meningitis?
Fits, raised ICP, hydrocephalus, cranial nerve palsies
What are the 4 ways of HIV transmission and their respective risks?
1) Sexual transmission (0.05-0. 5%) 2) IV drug use (0.67%) 3) Blood transfusion (90%) 4) Mother-to-child at birth or via breast milk (25%)
How is HIV-1 transmitted sexually?
It breaches mucosal barriers
What type of CD4 cells are the main target in acute infection prior to adaptive immune response?
Memory CD4 cells in the mucosa esp. in gut associated lymphoid tissue (GALT) which never really recovers
What is the immune response to HIV?
First CD8 T cells then neutralising antibodies
What are the 4 types of responders to HIV?
1) Normal progressors - AIDS in 8-10 years
2) Rapid progressors - AIDS 1-3 years
3) Long-term non-progressors - low level detectable viral RNA but AIDS-free indefinitely
4) Elite controller - < 50 cpm, AIDs-free, genetic association with MHC haplotype
How is HIV infection diagnosed?
- ELISA test for presence of anti-p24 serum antibodies (detects those who have seroconverted approx. 3 months post infection)
- Positive test is retested using diff ELISA or Western Blot
- Negative test may just mean that haven’t seroconverted yet
- Confirmation via RT-PCR to detect level of HIV RNA in blood
- Only RT-PCR can diagnose HIV before seroconversion
What are different types of HIV anti-retroviral therapy?
1) RT inhibitors (N)NRTI e.g. tenofovir, efavirenz
2) CCR5 inhibitors
3) Fusion inhibitor
4) Integrase inhibitors
5) Protease inhibitors
How many antiretrovirals are used in HAART combination therapy and why and what is the most common combination?
3 in order to avoid mutations
- 2 NRTI + 1 NNRTI/1 protease inhibitor
What does HAART do?
It controls HIV replication to below detectable levels in blood but virus is never eradicated and stopping treatment leads to rebound of HIV replication
What drugs is PrEP?
Tenofovir + emtricitabine