HIV and AIDs Flashcards
Through what mechanisms can HIV be spread?
- Sexual transmission
- Injection drugs misuse
- Blood products
- Vertical transmission
- Organ transplant
What cells do HIV attack?
The CD4 receptors on CD4+ lymphocytes
How does CD4 count change with progressing HIV infection?
As the disease progresses, CD4 count decreases and the HIV viral load increases. This results in an increased risk of developing infections and tumours. The severity of these illnesses is greater the lower the CD4 count
What is the normal CD4 count?
> 500
Most HIV diagnoses made at <200
How is HIV classified?
Broadly classified as either symptomatic or asymptomatic disease
Can also be staged 1-4, with stage 1 being asymptomatic disease and stage 4 being severe disease
What is an AIDs illness?
An illness that occurs due to HIV infection
What is the prognosis of a HIV diagnosis?
The timeline of HIV/AIDS is extremely variable from patient to patient but around 2/3 of patients will have an AIDS illness in 10 years and 50% of sufferers will be dead at 12/13 years
What is the natural history of HIV?
- Acute infection- seroconversion
- Asymptomatic
- HIV related illness
- AIDS defining illness
- Death
What are the characteristics of a seroconversion illness?
Occurs when HIV antibodies first develop
Affects 30-60% of patients
Onset abruptly around 2-4 weeks post-exposure#
Self limiting, resolve within 1-2 weeks
Symptoms include a flu-like illness, fever, malaise/lethargy, pharyngitis, lymphadenopathy and toxic exanthema
Typical presentation- looks like glandular fever but EBV serology negative
What is pneumocystis jiroveci pneumonia?
Commonest late stage (AIDS) infection.
Opportunistic infection that usually only occurs with a CD4 count of <200.
Usual history is of a dry cough and increasing breathlessness over several weeks
What investigations can be done for pneumocystis jiroveci pneumonia?
Chest x-ray
Induced sputum production or bronchoscopy for PCR
How is pneumocystis jiroveci pneumonia treated?
Primarily with cotrimoxazole
If contraindicated- pentamidine
What treatment can be given for HIV?
Antiviral therapy, started at diagnosis without waiting for symptoms to present
Can control but not eliminate disease
Given as triple combined pill including three drugs from two of the following drug classes:
-Reverse transcriptase inhibitors
-Integrase inhibitors
-Protease inhibitors
What is the required adherence to HIV treatment?
At least 90%
What are the common side effects of HIV treatment?
Lipodystrophy
Metabolic disorders
When can HIV treatment be adjusted and why?
After 4-6 weeks if viral load is not adequately suppressed
When should resistance testing for HIV treatment be done?
Resistance testing should be conducted in cases of newly diagnosed HIV. Treatment most commonly fails due to poor adherence causing viral mutation and resistance
What are the side effects of non-nucleoside reverse transcriptase inhibitors?
Skin rashes
Hypersensitivity
Drug interactions
Neuropsychiatric effects
What are the side effects of protease inhibitors?
Drug interactions
Diarrhoea
Lipodystrophy
Hyperlipidaemia
How is lipodystrophy managed?
Changing drugs
Cosmetic procedures
What measures can aid in HIV prevention?
Behaviour change/condoms
Circumcision
Treatment as prevention (undetectable = untransmissible)
Pre-exposure prophylaxis (PrEP)
Post exposure prophylaxis for sexual exposure (PEPSE)
What are the most common routes of spread of HIV in the UK?
Men who have sex with men Injecting drugs (less common but varies regionally)
What are the two types of HIV?
HIV-1
HIV-2
Which is the most common type of HIV globally?
HIV-1
How does HIV cause disease?
The virus attaches to cells with CD4 receptors on their surface and acts as a retrovirus. Retroviruses causes RNA to convert to DNA using reverse transcriptase
How is HIV diagnosed?
Diagnosed in laboratory by blood tests for HIV antigens and antibodies
What further lab tests can aid with management of HIV?
Viral load HIV resistance testing Avidity testing Subtype determination Tropism testing Drug levels
How is viral load used in practice?
HIV genome detection, or viral load allows detection of HIV RNA to monitor the effectiveness of HIV treatment. It can also be used diagnostically in cases of maternal antibodies
How is HIV resistance testing done?
Involves sequencing of polymerase and protease genes to allow for identification of specific mutations. It can be used to give a baseline at diagnosis, in cases of suboptimal treatment response, treatment failing and any other reason that a treatment change is desired
How can HIV be monitored?
CD4 count
Viral load
