Hepatitis A Flashcards
How many genotypes of HAV?
Three (I, II, III with subgenotypes IA, IB, IC, IIA, IIB, IIIA, IIIB)
When is the highest risk of trasnmission of HAV?
In the prodromal phase prior to symtom onset, which lasts about one week
Why is HAV so stable in the environmnet?
It can withstand, drying, low pH, detergents
How long do symptoms persist in HAV infection?
2-8 weeks
What percentage of adults and children have symptomatic HAV?
Adults >70%, children <30%
What percetage of patients with HAV have relapsing hepatitis?
12% have relapsing hepatitis, 7% have prolonged cholestatis with pruritis and fatigue
What are the 5 presentations of HAV?
1) Asymptomatic 2) Hepatitis (jaundice etc) 3) Cholestatic hepatitis 4) Relapsing hepatitis 5) Fulminant hepatitis
What are symptoms of acute liver failure in HAV?
Rapid deterioration in liver function, hepatitic encephalopahty, loss of cognitiive brain fucntion, motor dysfunction
What % of patients with acute liver failure from HAV recover?
70% recover spontaneously with conservative therapty (fluids treating hypoglycaemia and electrolyte imbalacne, Abx and rest) 30% require liver transplant
What are the signs of severe acute liver failure?
Deterioration of hepatic systemic function - coagulopathy, reduced INR, rising creatinine, drop in serum albumin, rising blood ammonia and hepatitic encepahlopahty
What are extra-hepatitic manifestations of HAV?
Acute kidney injury, cryoglobulinaemia, cholecysisits, pancreatitis, pleural effusion, pneumonitiis, haemolysis, rash, reactive arthrititis, neurological (mononeuritis, GBS, transverse myeltitis, neuritis)
Who is at risk of severe disease with HAV?
1) Patients with chronic liver disease 2) Severely immunosuppressed 3) Elderly (>50 y!!)
How long does viraemia and feacal shedding last in HAV infection?
Viraemia can last several months, faecel shedding can last for 6 months, and RNA detected in liver for up to 12 m
Is HAV IgM likely to be positive at onset of symptoms?
Can be falsely negative if collected <5 days post symptom onset
What region of the HAV genome is used for RT-PCR and what is used for genotyping?
PCR = 5’ NCR and genotyping = VP1-pX
What type of HAV vaccines are available in the UK?
Inactivated, either monovalent or combined with HBV or typhoid
Vaccine schedule for HAV vaccine
Primary dose gives 1 years protection, 2 doses 6-12 m apart >25 y immunity
What age is HAV vaccine licensed for?
Over 1 year
What is the antibody titre conisidered immune post HAV vaccine
20 mIU/ml
What are Havrix, Avaxim and Vaqta?
Monovalent HAV vaccines
What are Twinrix and Ambirix?
HAV and HBV dual vaccine
What does ViATIM vaccine protect against?
HAV and typhoid
Who would get HAV vaccine as pre-exposure prophylaxis?
Travellers, severe or chronic illness, haemophiliacs, MSM, PWID, lab workers, sewage workers, staff and residents at large residential institutions, people working with primates. Consider in: healthcare workers, staff at daycare facilities, food handlers
How effective is HNIG as PEP following HAV exposure?
80-90% effective if administered within 14 days
How long does HNIG last as passive immunisation for HAV?
4-6 months
How long must you wait between giving HNIG or HBIG and administering a live vaccine?
3 months
When would you test for HAV IgG in a contact?
To avoid giving HNIG unneccessarily - and only if you can get a result within 3 days and within the PEP window (either post contact or within 7 days of vaccine)
What is the infectious period of HAV?
2 weeks prior to first symptoms until 1 week post jaundice (or other symptoms if no jaundice)
Who would be considered immune post HAV contact? And what PEP would you consider?
Patients with 1) previous lab confirmed HAV infection, 2) 2 vaccines in the last 10 years 3) 1 vaccine in the last 12 months. No PEP
Who would be considered ‘primed’ post HAV contact? And what PEP would you consider?
Patients with 1) 2 vaccines >10 years ago 2) 1 vaccine >12 months ago. Vaccine only, no HNIG
How would you manage the index case of HAV outbreak?
Advise good hand hygeine! Exclude for 7 days from onset of jaundice, identify possible source, risk assessment and questionnaire
If a patient is vaccinated for HAV as a contact, can you still administer HNIG?
Yes, but only within 7 days of vaccine
HAV PEP for healthy 1-59 year olds
Within 14 d: vaccine only. After 14 d: vaccinate up to 8 weeks post exposure only if >1 case in household
HAV PEP for healthy <1 year old identified within 14 days
Not at nursery: vaccinate nappy changers. At nursery: vaccinate if >2 months
PEP for healthly 1 year old identified >14 days post contact
Reinforce hygeine, if not possible, exclude for 30 days. If unable to exclude, vaccinate all contacts at nursery aged >2 months
HAV PEP for >60 year olds
Vaccine and HNIG (within 14 days)
HAV PEP for immunosuppressed contacts
Vaccine and HNIG (within 14 days)
HAV PEP for patients with chronic liver disease
Vaccine and HNIG (within 28 days)
HAV PEP for food handler
Within 14 days: vaccinate. >14 days: move duties til 30 days post exposure
Which groups of people are at increased risk of spreading HAV?
A) People with doubfful personal hygeine B) All <5 years who atttend childcare C) Food handlers D) Clinical and social care staff
What vaccine coverage is required to disrupt transmission in a HAV outbreak?
40% vaccine coverage (assuming an R0 of 1.6)
Why should haemophiliacs be vaccinated against HAV?
HAV transmission has been associated with Factor VIII and IX, as HAV can withstand the inactivation process
Hep A incubation period
28 days, with a range of 15–50 days.
Hep A infectious period
2 weeks before to one week after onset of dark urine/jaundice/symptoms
