HIV Flashcards
Spread of HIV
Sexual transmission Injection drug misuse Blood products Vertical transmission Organ transplant
Point of Care HIV test
Blood sample from finger
60sec test
Standard test will confirm results
Immunology of HIV
Infects and destroys cells of the immune system especially T-helper cells that are CD4
CD4 receptors are not exclusive to lymphocytes - also present on surface of macrophages and monocytes
Natural history of HIV
Over course of infection;
CD4 count declines and HIV viral load increases
Increased risk of developing infections and tumours
Severity of these illnesses is greater the lower the CD4 count
Most AIDS diagnoses occur at CD4 count <200
Acute infection - seroconversion, asymptomatic, HIV related illness, AIDS defining illness, death
HIV classification
Original classification was clinical
Clinical stage I-IV
HIV Clinical Stage 1
Asymptomatic
Persistent generalised lymphadenopathy
Performance scale 1; asymptomatic, normal activity
HIV Clinical Stage 2
- Weight loss <10% of body weight
- Minor mucocutaneous manifestations
- Herpes zoster within last 5 yrs
- Recurrent URTIs
and/or performance scale 2; symptomatic, normal activity
HIV Clinical Stage 3
- Weight loss >10% body weight
- unexplained chronic diarrhoea >1 month
- Unexplained prolonged fever >1month
- Oral candidiasis
- Oral hairy leukoplakia
- Pulmonary TB within past year
- Severe bacterial infections
and/or performance scale 3; bedridden, <50% of day during last month
HIV Clinical Stage 4
- Pneumocytic carinii pneumonia
- toxoplasmosis of brain
- cryptosporidiosis with diarrhoea >1month
- cryptococcus extrapulmonary
- cytomegalovirus
- HSV
- progressive multifocal leukoencephalopathy
- candidiasis of oesophagus, trachea, bronhchi, lungs
- atypical mycobacteriosis
and/or performance scale 4 ; bedridden, <50% day last month
AIDS defining respiratory conditions
Tuberculosis
Pneumocystitis
AIDS defining neurology conditions
- Cerebral Toxoplasmosis
- Primary cerebral lymphoma
- Cryptococcal meningitis
- Progressive multifocal leucoencephalopathy
AIDS defining dermatology conditions
Kaposi’s sarcoma
AIDS defining oncology conditions
Non-Hodgkin’s lymphoma
AIDS defining gynaecology conditions
Cervical cancer
AIDS defining opthalmology conditions
Cytomegalovirus retinitis
What is HIV/seroconversion?
A seroconversion illness is when HIV antibodies first develop
Abrupt onset 2-4weeks post-exposure, self-limiting 1-2weeks
Symptoms generally non-specific and differential diagnosis includes a range of common condition
Describe symptoms of HIV seroconversion
Flu-like illness Fever Malaise and lethargy Pharyngitis Lymphadenopathy Toxic exanthema
“looks like glandular fever but EBV serology not in keeping”
Describe pneumocystitis jiroveci pneumonia
Commonest late stage (AIDS) infection
Opportunistic infection
CD4 cell count usually <200
Classical history of dry cough and increasing breathlessness over several weeks
Treatment; cotrimoxazole, pentamidine
Describe HIV antiretroviral therapy
Different classes of drugs acting on different stages in HIV lifecycle
Combination therapy is at least 3 drugs from at least 2 groups
Adherence needs to be >90%
cART can lead to normal life but side effects can be significant eg metabolic, lipodystrophy
Where do HIV treatments work?
Binding and entry
Reverse transcription
Integration
Transcription
Assembly
Release and Protease
When to start HIV patients on medication?
All patients at diagnosis regardless of CD4 and viral load
If CD4 < 350 cells/mm3 patients at risk of developing symptoms without being on treatment
If CD4 < 200 start asap
Any pregnant woman - start before third trimester
Three drug combo w/ treatment adjustment if viral load not adequately suppressed after 4-6weeks
Current HIV life expectancy
Life expectancy according to CD4 nadir (lowest before starting therapy)
<100 = 52 100-200 = 62 >200 = 70+
Describe nucleoside reverse transcriptase inhibitors
HIV antiviral
Side effects include marrow toxicity, neuropathy, lipodystrophy
Describe non-nucleoside reverse transcriptase inhibitors
HIV antiviral
Side effects include skin rashes, hypersensitivity, drug interactions, neuropsychiatric effects
Describe protease inhibitors
HIV antiviral
Drug interactions, diarrhoea, lipodystrophy and hyperlipidaemia
Describe integrase inhibitors
HIV antiviral
Side effects include rashes and disturbed sleep
What to do if a patient develops lipodystrophy?
Change drugs
Less likely to happen with newer agents
Cosmetic procedures
- facelift
- liposuction
- fillers
Describe HIV prevention
Behaviour change and condoms
Circumcision
Treatment as prevention
Pre-exposure prophylaxis (PrEP)
Post- exposure prophylaxis for sexual exposure
Describe the virology of HIV
Two types; 1 and 2
4 groups
- HIV-1-M responsible for epidemic
- N, O and P uncommon
Within N group there are 9 subtypes; ABCDFGHJK
HIV is a lentivirus (belongs to retrovirus group)
- cause slow infections with long incubation
- RNA to DNA using reverse transcriptase
HIV tests
Antibody (during first month tests may be negative) Antigen Then; - viral load - CD4 count - typing - avidity - tropism - resistance tests - drug levels
Describe HIV resistance testing
Sequencing of the polymerase and protease genes
Identification of specific mutations that confer resistance to antiviral drugs
Used for
- baseline at diagnosis
- suboptimal treatment response
- treatment failing
- want to change treatment for another reason
Body fluids to be handled with the same precautions as blood
CSF Pleura, peritoneal, pericardial fluid Breast milk Amniotic fluid Vaginal secretions/semen Synovial fluid Any other body fluid w/visible blood Unfixed tissues and organs Saliva - dental procedures Exudate/tissue fluid from burns or skin lesions
What to do after body fluid exposure risk?
Wash off splashes on skin with soap and running water
Exposed mucous membranes including conjunctivae should be irrigated copiously with water
Encourage bleeding if broken skin
Wash out splashes in eye, nose, mouth
Involve Occupational Health
Send BBV screen for storage
Describe HIV post-exposure prophylaxis
if high risk blood/body fluid
Commence within 72hours of exposure
Complete 28day course
HIV test 2 months after PEP
