HIV Flashcards
How is HIV spread?
Sexual transmission IV drug users Blood products (transfusions) Vertical transmission (maternal) Organ transplant
Who are high risk categories for HIV?
IV drug use
MSM
What are the two distinct HIV viruses and which is more common?
HIV-1
HIV-2
HIV-1 Group M is most common
How does the HIV virus infect someone?
It attaches to glycoproteins on cell surface and targets T-Helper cells that have CD4 receptors
What co-factor is present for attachment of HIV to CD4 cells?
CCR-5
How do you diagnose HIV?
combined HIV antigen and antibody tests
How long does it take before you can get a positive HIV test? What is the significance of this?
After exposure to the infection, it can take up to 3 months to become positive
This window period can vary between individuals and is crucial because an individual is still highly infectious and can have false-negative results
What is the viral load?
The amount of HIV virus in the blood (copies/ ml blood)
What is the viral load used for?
To monitor the effectiveness of HIV treatment
and used for diagnosis in babies in the presence of maternal antibody
How does the viral load vary with disease progression?
Initial HIV viral load = high during acute infection
Falls to a low level
Only rises again in the later stages of disease (6-8 years of infection)
What influences the disease progression?
Age
HLA type
History of seroconversion illness
How do you monitor HIV infection?
CD4 lymphocyte count
HIV viral load
Clinical features
How does the HIV virus replicate?
Each virus has 2 chains of RNA, the virus needs a host cell to replicate and must be transcribed into DNA first
Integrase facilitates integration into host cell DNA
Contains protease enzyme needed for maturation of virus
At what CD4 count do most AIDS diagnoses occur?
What is the normal CD4 count?
CD4 count < 200
The severity is greater the lower the CD4 count
Normal CD4 > 500
What problems can occur during virus replication + what is the significance?
Lack of accuracy -> causes virus diversity
Persistent infection of cell -> ongoing opportunity to transmit
What is the difference between HIV and AIDS?
HIV= asymptomatic with HIV infection
AIDS= weakened immune system leading to infections + tumours that are classified as AIDS illnesses
Describe the first stage of HIV?
note there are 4 clinical stages
Asymptomatic
Generalised lymphadenopathy
Describe the second stage of HIV
Weight loss
Recurrent respiratory infections
Herpes zoster
Mucocutaneous manifestations (fingal nail, oral ulcerations, angular chelitis)
Describe the third stage of HIV
Weight loss > 10% of body weight
Chronic diarrhoea > 1 month
Unexplained Prolonged fever > 1 month
Oral candidiasis (thrush)
Bacterial infections (e.g. pneumonia, bone/joint infection, empyema)
Tuberculosis
Oral hairy leukoplakia (white hairy patch on tongue)
Performance (activity level): bedridden
Describe the fourth stage of HIV
HIV wasting syndrome Pneumocystic pneumonia Toxoplasmosis of the brain Recurrent severe bacterial pneumonia Chronic herpex simplex infection Progressive multifocal leukoencephalopathy Kaposi's Sarcoma Cytomegalovirus infection of organs HIV encephalopathy
Many more symptoms + diseases…
Give some examples of AIDS defining conditions
Tuberculosis Pneumocystis Cerebral toxoplasmosis Cryptococcal meningitis Progressive multifocal leukoencephalopathy Kaposi's sarcoma Non-Hodgkin's lymphome Primary cerebral lymphoma Cytomegalovirus retinitis Cervical cancer
(try remember a few examples)
What is the progression + prognosis?
- Acute infection- seroconversion
- Asymptomatic
- HIV related illness
- AIDS defining illness
- Death
What is a seroconversion illness?
It is the period of time in which HIV antibodies develop and become detectable
Occurs in first few weeks of initial infection
It is often accompanied by flu-like symptoms
What are the flu-like symptoms that accompany seroconversion of HIV?
fever malaise lethargy pharyngitis lymphadenopathy
What are the classes of HIV antiviral drugs?
Reverse transcriptase inhibitors
Integrase inhibitors
Protease inhibitors
These different classes act on different stages in HIV lifecycle
Give some examples of specific antivirals
AZT - Zidovudine
DDI - Didanosine
What is combination antiretroviral therapy?
Means at least 3 drugs from at least 2 classes are used
This is to prevent drug resistance (that occurs with monotherapy)
Why does antiviral patient adherence need to be good?
Needs to be over 90% or patient will develop drug resistance and viral mutation
What side effects are there for the reverse transcriptase inhibitors?
Nucleoside reverse transcriptase inhibitors: neuropathy, marrow toxicity, lipodystrophy
Non-nucleoside reverse transcriptase inhibitors: nightmares, hypersensitivity, skin rashes
What side effects are there for the protease inhibitors?
Drug interactions, diarrhoea, lipodystrophy, hyperlipidaemia
What side effects are there for the integrase inhibitors?
Rashes
When should treatment be started?
Start treatment in all patients regardless of CD4 count
If CD4 < 350 - start antivirals
If CD4 < 200 need to start PCP prophylaxis
Any pregnant women - start before third trimester
What is the treatment length for HIV?
Life long
Treatment may be altered if there is drug resistance/ side effects
What is the life expectancy with HIV?
According to CD4 Nadir (lowest CD4 before starting therapy)
Earlier treatment started = better outlook
Note: CD4 + life expectancy <100= 52 years 100-200= 62 years >200= 70+ years
What challenges occur with HIV?
- Osteoporosis
- Cognitive impairment
- Malignancy
- Cerebrovascular disease
- Renal disease
- Ischaemic heart disease
- Diabetes
What HIV prevention is there?
Behaviour change and conditions
Circumcision
Treatment as prevention: best form of prevention
• Pre-exposure prophylaxis (PrEP)
• Post- exposure prophylaxis for sexual exposure (PEP)
