Session 6- Blood Borne Viruses- HIV and Hepatitis Flashcards
HIV life cycle
1- free virus
2- binding and fusion- binds to CD4 receptor
3-virus penetrates cell
4-reverse transcription RNA TO DNA
5- integration- viral DNA is combined with the cells own DNA by the integrase enzyme
6- transcription- when infected cell divides viral DNA is read and long chain proteins are made
7- assembly viral protein chains come together
8- budding- immature virus pushes out of cell membrane with it
transmission
: Contact of infected bodily fluids with mucosal tissue /
blood / broken skin – sexual contact, blood transfusion, contaminated needles,
vertical transmission to fetus during delivery. Some medical procedures carry a risk
of transmission
what happens when CD4 cell count drops
Once CD4 cell count drops below 350 cells/µl you begin to get more symptoms – a cold you can’t shake, athlete’s foot
Once less than 200 cells/µl – you begin to see severe infections,
AIDS defining symptoms and cancers linked with HIV/AIDS.
diagnostic tools for HIV
– a) serology – detects both antigens (viral proteins) and antibodies to HIV in the blood,
b) PCR – detects the
viral nucleic acid
c) rapid testing
treatment of HIV
Every patient is treated as soon as possible with ARVs (anti-retroviral drugs)
regardless of CD4
how do antiretroviral drugs work
Anti-retroviral drugs work by targeting the binding (CCR5 – entry inhibitor), the
enzymes responsible for incorporation of viral DNA into host DNA (Integrase
inhibitor), for breaking down the large proteins into smaller units (protease inhibitor)
during the maturation phase of the viral life cycle and reverse transcriptase (Nonnucleoside reverse transcriptase inhibitor (NNRTI ) – non-competitive inhibitor or
Nucleoside reverse transcriptase inhibitor (NRTI) - competitive substrate inhibitor)
strategies to reduce prevalence of HIV
- Increase condom usage
- ARV treatment as prevention
- Wide-spread testing/screening
- Prevention of mother-to-child transmission
- Post-exposure prophylaxis (PEP)
- Pre-exposure prophylaxis (PrEP)
- Male circumcision
- Combine the above
what viruses cause collateral liver damage
EBV- Epstein Barr Virus
CMV- cytomegalovirus
VZV- Varicella Zoster
icteric sclera
white of eye turns yellow
what kind of hepatitis does viral hepatitis cause
intrahepatic
what does raised bilirubin indiacte
either the pre-hepatic, intrahepatic or extrahepatic
processing of this product.
what does raised ALT AST indicate
If ALT (Alanine transaminase) or AST (Aspartate aminotransferase) are elevated it tells us there is hepatocyte damage and the problem is intrahepatic.
ALT
AST
alanine transaminase
aspartate aminotrasnferase
raised ALP indicates…
If ALP (Alkaline phosphatase) is elevated there is a problem in the biliary tract- extra hepatic
transmission if Hep B
Transmission is predominantly vertical (75% of cases globally) but also through
sexual contact, intravenous drug use, close household contacts (low risk) where
there is significant blood exposure and health care workers via needle stick injuries.
symptoms of hep b
jaundice, fatigue, abdominal pain,
anorexia/nausea/vomiting and arthralgia (joint pain)
HEP B serology
in a blood test you can detect HBsAg & HBsAb, HBeAg
& HBeAb, HBcAb (IgM followed by IgG (HBcAg is undetectable in blood))
C diff
Clostridioides difficile [klos–TRID–e–OY-dees dif–uh–SEEL]
a gram-positive, anaerobic, spore-forming bacillus that is responsible for the development of antibiotic-associated diarrhoea and colitis (bowel inflammation).
microbiology of c diff
C. difficile is an anaerobic bacteria. The presence of oxygen is inhibitory to its growth.
Their sensitivity to oxygen limits the conditions under which it can colonise the
human body or cause disease.
C. difficile is a minor component of the bowel microflora. Colonisation of the large
bowel is present in up to 5% of the population.
why do patients develop c diff
When the balance of gut microorganisms is disrupted, C. difficile starts to dominate
and colonize the large intestine.
after use of antibiotics
toxins of C diff
C. difficile produces two important types of toxins, A and B.
Toxin A is an enterotoxin that causes excessive fluid secretion, but also stimulates an
inflammatory response and has some effect on damaging cell structure.
Toxin B is a cytotoxin and damages protein synthesis and the cell structure.
risk factors associated with Clostroidioes Difficille
Antibiotic exposure, older age and hospitalisation Severe illnesses, immune suppression, and gastric acid suppression
when to suspect C diff
diarrhoea
who has received antibiotics within the previous 3 months, has been recently
hospitalized, and/or has an occurrence of diarrhoea within 48 hours or more after
hospitalization.
diagnoses of CDI
Tests aim to identify the C. difficile bacteria and the presence of toxin.
Stool assays for C difficile include the following:
Enzyme immunoassay (EIA): for glutamate dehydrogenase produced by C.
difficile.
Real-time polymerase chain reaction (PCR) assay for toxin gene
EIA for detecting toxins A and B
