HIV Flashcards
What type of virus is HIV?
ssRNA
Retrovirus
Infects and replicates within the human immune system using host CD4 cells (T helper)
How dos HIV replicate?
Penetrates host CD4 cell and empties its contents
Single strands of viral RNA converted into dsDNA by reverse transcriptase and combined with host DNA.
Infected cell divides reading viral DNA and creating viral protein chains and immature virus pushes out of cell
Virum matures hen protease enzyme cuts the viral protein chains and they assemble to create a working virus, destroying host cell
How are CD4 levels affected by HIV? How does this affect the patient?
Upon seroconversion (producing anti-HIV antibodies during primary infection) patient may experience flu like symptoms
CD4 levels fall in response to initial rapid replication of HIV and at this stage person is extremely infectious
Over the next months-years the infection can enter a latent phase
Patient may be initially asymptomatic but with CD4 levels falling and viral load increasing, they may become more susceptible to infections
How can HIV be transmitted?
Unprotected sexual contact - vaginal, anal or oral
Sharing of injecting equipment
Medical procedures - blood products, skin grafts, organ donation and artificial insemination
Vertical transmission - from mother to child in utero, during childbirth or breast feeding
When are people more likely to catch HIV?
Exposed to higher vital level
Have STI causing anogenital inflammation
Breaks in skin or mucosa
Who are at risk groups for HIV?
Men who have sex with men
IVDU
Those in high prevalence areas
Those who have had unprotected sex with a partner who has lived or travelled in Africa
What are clinical features of HIV seroconversion illness?
2-6 weeks after exposure Non-specific flu-like illness Fever Muscle aches Malaise Lymphadenopathy Maculopapular rash Pharyngitis
What are features of symptomatic HIV?
After a latent phase, HIV becomes symptomatic
Weight loss
High temperatures
Diarrhoea
Frequent minor opportunistic infections e.g. herpes zoster or cadidiasis
What is AIDS?
Development of AIDS defining infections and malignancies such as:
Pneumocystic jiroveci pneumonia
Non-hodgkin’s lymphoma
TB
What investigations for HIV? When?
Fourth-generation tests
ELISAs that test for serum HIV antibodies and p24 antigen test
Give reliable results 4-6 weeks (antibodies developed 4/6 weeks) after exposure
p24 antigen test from 1 week to 3/4 weeks post exposure
Rapid test kits give results in 30mins however less accurate and still require ELISA
What is management for HIV?
Highly Active AntiRetroviral Therapy
Aims to reduce viral load to undetectable load
This reduces the risk of AIDS and onward transmission
What are types of HAART drugs? How many are used?
Nucleoside reverse transcriptase inhibitors NRTI
Protease inhibitors PI
Non-nucleoside revere transcriptase inhibitors NNRTI
Integrase strand transfer inhibitors
At least 3 drugs used:
2 NRTIs + 1 PI or NNRTI
Used in combination to target the enzymes used in vital replications and maturation
Compliance is key and patient must keep taking drugs for rest of lives
How is HIV monitored?
CD4 count HIV viral load FBC U&Es Urinalysis ALT, AST, bilirubin
In what period can post-exposure prophylaxis be sued?
72 hours
How long does PEP course last?
Month
Truvada + Raltegravir
