Week 7 - Blood Borne Infections Flashcards
Name some aids defining illnesses?
Oral candidiasis
Kaposis’s sarcoma
Pneumocystis pneumonia
Name some features of human immunodeficiency virus?
Retro virus - RNA
How does HIV colonise a human?
Infects and replicates in immune system - CD4 T-cells
Destroys these lymphoctes when replicates which is why immune system gets weakened
What are the stages of HIV infecting a cell?
Virus binds to CD4 molecule and one of 2 corereceptors
Virus fuses with cell and then penetrates it
Empties contents into cell
Single strands of viral RNA are converted to double stranded DNA by reverse transcriptase
Viral DNA is combined with cells DNA by integrase enzyme
When infected cell divides the viral DNA is read and long chains of proteins are made
These viral proteins come together and immature virus is produced
This pushes out of cell, taking some membrane with it, and breaks free
Virus matures by cutting protein chains by protease enzyme into individual proteins that combine to make working virus
Describe the 4 stages of HIV infection?
Acute infection/seroconversion - very infectious stage, high viral load, drop in CD4 count, lasts about 3 months
Latent infection - 2-10 years on average but can be up to 20-3@ years, low viral load, CD4 count nearly normal
Symptomatic infection - symptoms such as other infections that wont go away, viral load increases, CD4 count decreases
Severe infection/aids - very low CD4 count, very high viral load
What is the CD4 count in aids?
<200
What are the main symptoms of acute HIV infection?
Fever Weight loss Pharyngitis Mouth sores Oral thrush Myalgia Liver and spleen enlargement Malaise Headache Neuropathy Rash Nausea Vomiting
List some HIV associated conditions?
Cryptococcal meningitis TB Osteoporosis Heart disease Stroke HPV hIV wasting syndrome
How can HIV be transmitted?
Sexual transmission- vaginal, anal and oral
Sharing if injecting equipment - depends on viral load
Vertical transmission - in utero, during childbirth or breast feeding
Medical procedures - blood products, skin grafts, organ donation
What factors affect HIV transmission?
Type of exposure Viral level Other STIs - local effects and effects on immune system Condom use Breaks in skin or mucosa
What are the diagnostic tests for HIV?
Blood tests for - HIV antigen (made by virus), HIV antibody (made by immune system), finger prick blood test, saliva test
When should you start drugs for HIV?
As soon as possible, regardless of CD4 count
What are the aims of HIV treatment?
Undetectable HIV viral load, reconstituted immune system, good quality of life, normal life span, reduced risk of transmission
How do HIV drugs work?
Prevent viral replication in infected cell
Why do we use 3 drugs to treat HIV?
Millions of viruses are made each day so they mutate very fast
If we give 3 drugs its harder to develop resistance to all 3 but patients must keep taking all the drugs for this to happen
