Bloodborne Diseases: HIV and Hepatitis *on IMs*

Question 1

• give some clinical signs of HIV
• outline the typical structure of a virus
• give specific details of the structure of HIV and its mechanism of action.
• how is HIV transmitted?

Answer 1

• oral candidiasis, PCP (pneumocystic pneumoniae), kaposi’s sarcoma (red bumps on skin)
• genome either rna or dna (ss or ds), capsid which is a protein shell that protects the genome, lipid envelope present or sometimes not, replication strategy in host cells as they can’t alone.
• human immunodeficiency virus, a retrovirus meaning it has ssRNA but using reverse transcriptase it converts into DNA and insterts into a host cell DNA. It infects cells with CD4 surface receptor (t lymphocytes/macrophages). HIV replicates inside cells then destroys the cell, causes inflammation, spreads to more cells
• contact of infected bodily fluid with mucosal tissue/blood/broken skin eg sex, blood transfusion, perinatal, contaminated needles.

Question 2

• what are the stages of a HIV infection?
• give the main symptoms of HIV.
• give 3 conditions associated w HIV.
• give 4 factors affecting HIV transmission.

Answer 2

• 1:primary infection, cd4 count around 1000 cells/microlitre, very infectious.2:latent infection, cd4 drops to around 800 cells. 3:symptomatic infection, cd4 350 cells. 4:severe infection/aids, cd4 v low at <200.
• mouth sores & thrush, headache, malaise, skin rash, nausea, oesophageal sores, splenomegaly, fever, weight loss
• AIDS, oral Candida/thrush, TB, PCP, osteoporosis, HPV, hepatitis.
• 1:type of exposure ie type of sex, needle vs mucous membranes, 2:viral load ie if low less transmissible, 3:condom use, 4:breaks in skin or mucosa.

Question 3

• what are 3 diagnostic tests for HIV?
• what strategy is used to reduce prevalence of HIV?
• what are the main aims of HIV treatment?
• when should someone w HIV start treatment and why?

Answer 3

blood tests: 1-serology=detecting HIV antigen or antibody, current tests detect both, result on same day, may get false neg. 2-PCR=detects HIV nucleic acid, v sensitive, expensive and results slow. 3-rapid tests=home kits, sample of saliva or blood, may get false positives

• anti retroviral drugs (ARVs), preventing mother to child transmission, widespread testing, increase condom usage, male circumcision.
• to get an undetectable HIV viral load, to recover the cd4 count, reduce general inflammation, reduce transmission (UNDETECTABLE=UNTRABNSMITTABLE)
• asap, regardless of cd4 count

Question 4

• which ARVs are used in HIV treatment?

- why are 3 ARVs given?

Answer 4

• nucleoside reverse transcriptase inhibitor, protease inhibitor, CCR5 entry inhibitor, integrase inhibitor
• bc virus mutates and adapts every 2-3 rounds and millions are made each round, resistance can develop in days but harder if patient takes x3 drugs

Question 5

• define hepatitis, describe hepatic viruses.
• from hepatitis A-E which are chronic and explain how each is spread.
• why is jaundice commonly seen in patients w hepatitis?

Answer 5

• hepatitis=inflammation of the liver, replication specifically in hepatocytes, destroys the hepatocytes
• hepA+E=faeco-oral, not chronic, hepD=blood/sex/vertical, chronic w HepB, HepB+C=blood/sex, chronic
• because liver doesn’t function as normal therefore the bilirubin is unconjugated and goes into the bloodstream.

Question 6

• give the 5 tests done to test liver function.
• give modes of transmission and symptoms of HepB
• how long does the virus incubate for?
• describe HepB serology.

Answer 6

1) bilirubin, 2)liver transaminases (alanine-ALT, aspartate-AST) 3)alkaline phosphotase (ALP) 4)albumin 5)tests of coagulation ie PT and INR
- vertical eg perinatal, sex, injections, HCW via needle stick injuries
- symptoms=jaundice, anorexia, fatigue, abdominal pain.up to 50% have no symptoms
- 6 weeks to 6 months
- first a surface antigen followed by e-antigen (highly infectious here), then core Ab followed by e-Ab and finally surface Ab (when infection is cleared/recovery), core Ab persists for life.

Question 7

• define a chronic HepB infection.

- what is the treatment for a HepB infection

Answer 7

• persistence of the surface antigen after 6 months.
• no cure, bc virus is integrated into host genome (all cells in body have virus), lifelong antivirals (not needed for all as some ppl are inactive carriers), vaccination as a preventative-produces surface antigen response

Question 8

• who is at high risk of HepC?
• what % of cases become chronic? Are there symptoms & if so give symptoms.
• what blood tests do we use?
• can HepC be cured? Is there a vaccine?

Answer 8

• people who inject drugs IV eg heroin, crack (90% of cases), sexual contact, perinatal transmission
• 80% become chronic, some of them develop liver cirrhosis
• 80% have none, for the 20%-fatigue, nausea, anorexia, abdo pain.
• serology=anti HepC antibody only, viral PCR just confirms ongoing infection
• can be cured using antiviral combo, no vaccine so can get reinfected.