Blood Borne Viruses: HIV and Viral Hepatitis Flashcards
The global total of people with a HIV infection is 37 million, with 107,800 in the U.K. Where is there a high prevalence?
Subsaharan Africa.
How can a HIV infection present?
Immunocompromised, so recurrent infections of varying types and weight
loss. May present with: Oral candidiasis, Kaposi’s sarcoma (skin lesions/rashes) and PCP (pneumocytic pneumonia - consolidation). Anyone with HIV may be infected by any pathogen, but commonly: reactivation of latent viral infections (including EBV), fungi (yeasts and mounds) and Protozoa (parasites).
What is the outcome of HIV?
Chronic infection, with or without disability and death is probable if it’s diagnosed late and untreated.
In the U.K., 67% of HIV cases are men, so 33% female, but globally this is higher due to ________ _____________. Globally 43% of cases are MSM and 57% _____________, but in the U.K. there are more _______ diagnoses. Half of these are _______ ____________. IV drug users make up __/1000 cases.
Gender inequalities Heterosexual MSM Black African 2
The rate of sexual transmissions of HIV being MSM are increasing, but what danger is seen is diagnosed heterosexuals?
The average are of diagnosis of a heterosexual wit HIV in the U.K. is 40. Over 50% are diagnosed at a late stage.
Infection of HIV acquired in the U.K. _________ that acquired abroad. There are hotspots within the country, including the ___________. ___% of people living with HIV, do not know that they have it.
Exceeds
Midlands
17
Describe the genome of the HIV virus
Genome - RNA or DNA (never both), single or double stranded.
What is the capsid of the HIV virus and what is its shape?
The capsid is the protein shell that protects the genome; it’s helical (rod shaped/coiled) or icosahedral (spherical/symmetric).
Does the HIV virus have a lipid envelope?
The lipid envelope is either present or absent. If present, it is derived from the host cell’s membrane and contains virus specific proteins (antigens).
Name 4 viral structure and behaviour components of HIV.
Genome, capsid, lipid envelope, replication strategy.
What does it mean that the Human Immunodeficiency Virus is a retro virus?
ssRNA–>DNA–>ssRNA
How does HIV infect cells?
It infects cells with a CD4 cell surface receptor: T helper lymphocytes (monocytes/macrophages) - replicates inside cells and destroys it, causes inflammation then spreads to infect more cells.
At a cellular level, what does HIV do? Include the following enzymes in the description: integrase, reverse transcriptase and protease.
- Free virus binds and fuses to CD4 molecule and coreceptor. 2. Injection - penetrates cell and contents emptied into. 3. Reverse transcription. 4. Integration of viral DNA into cell’s own (integrase). 5. Transcription. 6. Assembly - sets of viral protein chains come together. 7. Budding - immature virus pushes out of cell, taking some membrane with it and breaking free. 8. Protease enzyme cuts chain, so individual proteins can combine to form a working virus.
How is HIV transmitted?
Contact of infected bodily fluids with mucosal tissue/blood/broken tissue: sexual contact, transfusion, contaminated needles, perinatal/vertical transmission.
Explain the different stages of a HIV infection.
Primary infection/seroconversion - in months, CD4 dips and viral load is very high (infectious).
Latent infection - viral load rises from dropped viral ‘set point’ steadily and the CD4 count starts to drop again.
Symptomatic infection - after years, contamination with CD4 count= 350 cells/microL.
Severe infection/AIDS with CD4<200, maybe cancer.
As their CD4 count drops, people with HIV are more vulnerable infection and varying pathologies, list some factors affecting transmission.
Type of exposure, viral load in blood, condom use, breaks in skin/exposure.
Risk of HIV (not usually high) guides the use of ____________. Living with HIV: ______ ___________ and quality of life are now excellent in the general population. The general life expectancy of the population is 77yrs, which is the same as if you were HIV positive and had early ___________, there was treatment ___________ and healthy living. Late detection leads to a worse ____________. If a region has a high prevalence, ___-_____ testing is suggested.
Prophylaxis Life expectancy Detection Adherence Prognosis Opt-out
What diagnostic tests can be used for HIV?
Blood tests/serology, PCR and ‘rapid’ tests.
Explain the blood test for HIV.
Blood tests - serology, for HIV antigen and Ab, current test detects both on same day (false negative if test too early - before 4 weeks).
Explain the PCR test for HIV.
PCR - detects HIV nucleic acid, highly sensitive, detects very early infection (up to 1 week), not used for initial testing, but follow up/treatment response.
Explain the ‘Rapid’ test for HIV.
‘Rapid’ tests - low cost and under an hour, may be done at home and posted, usually detects HIV Ab with finger prick/saliva - if negative, then accurate, but false positive needs conformation with serology.
How is it decided who is tested for HIV?
If the rate is over 2/1000, then it’s recommended that everyone be tested. Also, otherwise unexplained multi-infection presenting to the GP: repspiratory - bacterial pneumonia/TB, neurological - meningitis/dementia, dermatological - severe psoriasis/recurrent or multi-dermal shingles, gastrological - chronic diarrhoea/weight loss, haematological - any unexplained abnormality, oncology - lymphoma/anal cancer, gynaecology - CIN, any STI/Hep B/C.
What is the aim of HIV treatment?
To get an undetectable HIV viral load, reconstitute the CD4 count (immune system), reduce general inflammation and the risk of transmission. Get a good quality of life and normalise the life span.
