Blood Borne Viruses Flashcards
Conditions associated with HIV later stage
Oral candidiasis Kaposis sarcoma (rash) Pneumocystis pneumonia (PCP)
Pathogen complications HIV
Reactivation of virus (those that lie dormant and then reappears (latent)
Fungus (yeast, mould) common
Protozoa common
Outcomes for HIV
Chronic infection +/- disability
Death
Management
Structure virus
Genome (RNA vs DNA) double/signle strand
Capsid (protein shell) - helical vs icsohedral
Lipid envelope (derived from host cell membrane) present/absent
Replication strategy
HIV virus type
Retrovirus - inserts RNA into host cell, uses reverse transcriptase to convert it to DNA, converts back
Genetic material HIV
Single stranded RNA
How does HIV infect?
Gp120 (glycoprotein on HIV) infects cells that have CD4 surface receptor
(Mostly T helper lymphocytes)
Cells with CD4 receptor
T helper lymphocytes
Monocytes/macrophages
What does HIV do once inside cell?
Replicates:
Destroys cell
Causes inflammation
Spreads to/infects more cells
Enzymes important in HIV
Reverse transcriptase - ssRNA converted to dsDNA
Integrase - Viral DNA intergrated into host cells DNA
Protease - new viral particles cut to combine to form new activated virus
Receptors HIV binds to
CD4
CCR5
CXCR4
Transmission of HIV
Sexual contact
Transfusion
Contaminated needles
Perinatal (usually during delivery through infected birth canal or through breast milk)
Stages of HIV infection
Primary infection (seroconversion)
Latent infection
Symptomatic
Severe infection/AIDS
Primary infection
Flu like symptoms (CD4 low)
Viral load high - infectious
Latent infection
Viral load lowers
CD4 count recovers
Dormant virus
Symptomatic infection
CD4 count below 350
Viral load increasing
Severe infection/AIDS
CD4 count below 200 cells per microlitre
Viral load very high
Symptoms of HIV
Malaise Headache Rash Nausea/vomitting Enlarged spleen Mouth sores/thrush Fever Weight loss
Factors affecting HIV transmission
Tye of exposure
Viral load in blood
Condom use
Breaks in skin/mucosa (from other STI’s/sexual assault)
Highest risk of transmission from exposures
Transfusion (very high risk)
Anal intercourse (receptive) (1.1%)
Injection (1/149)
Living with HIV now
Life expectancy and quality of life very good
80 years
Factors affecting life expectancy with HIV
Early detection (good starting CD4 levels)
Treatment
Adherence
Healthy habits (no smoking, limit alcohol, exercise)
HIV tests
Blood test - serology (test for antigen and antibody) - falso negative possible
PCR - highly sensitive (used for follow up not initial as expensive)
Rapid at home tests - low cost (finger prick, oral) false positives - confirm with serology
Who should be tested?
Everyone Resp: bacterial pneumonia/TB Neuro: meningitis/dementia/neurotoxoplasmosis Derm: severe psoriasis Gastro: chronic diarrhoea/weight loss Haem: anaemia with no cause? Onc: lymphoma, anal cancer Gynae: cervical intraepithelial neoplasia ANY STI, HEPB, HEPC
Treatment HIV
Anti-retroviral drugs
Aims of HV treatment
Undetectable viral load = 0 risk of transmission
Restablish CD4 and immune system
Reduce systemic inflammation
Normal lifespan/quality of life
Drug targets HIV
Attachment
Reverse transcriptase inhibitors
Protease inhibitors
Integrase inhibitors
When to start HIV treatment?
CD4 <350
As early as possible
Anti retrovirals classes
Nucleoside reverse transcriptase inhibitor AND
- non nucleoside reverse transcriptase inhibitor OR
- Protease inhibitor
OR - Integrase inhibitor
OR - CCR5 (entry) inhibitor
Why do HIV patients need more than 1 ARV?
Virus mutates
Resistance to drug develops
2-3 drugs = harder to develop resistance
Strategies to reduce HIV prevalance
Condom use ARV prevention treatment Testing/screening Post exposure prophlaxis Male circumcision (voluntary)
New HIV treatments
Pre exposure prophlaxis (if dont have HIV but at risk)
Dual therapy
Injectable drugs (every 2 months instead of daily)
Monoclonal antibodies (Ibaluzimab attachment inhibitor)
VACCINE??
Ethical dilemmmas HIV
Psychological impact of diagnosis
Stigma
Patient confidentiality vs health of others
Blood borne viruses examples
HIV
Hep B
Hep C
Neurological problems associated with HIV
Neurotoxoplasmosis - parasite in brain
