14. Viral hepatitis Flashcards
How is hepatitis A spread?
Via the faecal-oral route
Where does viral hepatitis tend to be more common?
Tends to be more common in countries in which access to clean water is poor. There are also occasionally outbreaks in schools and amongst MSM.
What is the incubation period of viral hepatitis?
Incubation period: 2-6 weeks
Who does Hep A cause clinical problems in?
Often subclinical (often people don’t realise that they have it). Tends to cause worse clinical problems in people with underlying liver disease e.g. Hep B, alcoholics (these people should be targeted for immunisation)
Is Hep A virus notifiable?
Yes
What are risks of contracting Hep A virus?
Occupational risks (sewage workers and plumbers are at risk, chefs not washing hands properly may spread it to others). GUM clinics. Low socioeconomic status
What outbreak occuredin Shanghai blood clams (1988) and New Zealand blueberries 2011?
Hep A outbreak
What is the natural history of Hep A?
2-6 weeks (15-50 days) after the infection
you get hepatitis (transaminitis i.e. rise in ALT) (lasts approx. 4 weeks)
What is the diagnostic test for Hep A?
IgM anti- hepatitis A virus (If you have had the vaccine, you will have a high IgM AND high IgG but WITHOUT the high ALT). HAV detectable in stool for several weeks.
Who is the vaccine recommended for in hep A?
Recommended for high risk populations e.g. occupational, those who travel often
Describe the features of HAV?
The family Picornaviridae, genus hepatovirus.
Single-stranded, positive sense RNA genome.
Quasi-enveloped virions
What are clinical manifestations of HAV?
Wide disease spectrum from asymptomatic to fulminant hepatitis. Strong correlation with age: <10% symptomatic among children <6 years old versus 70% in adults. Typical symptoms: fever, malaise, anorexia/nausea, abdominal discomfort, diarrhoea, jaundice. Extra-hepatic diseases. Acute presentation; 99% resolution.
HAV is an aetiology for chronic hepatitis true or false?
FALSE. HAV NOT an aetiology for chronic hepatitis
What does acute HAV infection show on serology?
IgM reactive; unlikely if bilirubin level < 30umol/L
What does past HAV infection show on serology?
IgM non-reactive, IgG reactive
How is Hep A managed?
Supportive Tx.
Pre-exposure immunisation among population at risk.
Post-exposure prophylaxis:
within 14 days of exposure to index case: HAV vaccine +/- HNIG (for 60 years and above, chronic liver diseases inc CHB/CHC, immunocompromised contact)
Over 14 days: HAV vaccine +/- HNIG (for chronic liver diseases inc CHB/CHC, immunocompromised contact)
What is the infectious period in HAV?
Infectious period of index case: two weeks before onset of first symptoms and until one week after the onset of jaundice
What are features of Hep B virus?
The family Hepadnaviridae.
Double-strained DNA with reverse transcriptase.
Enveloped virions.
10 genotypes (A-J) with distinctive geographic distribution.
How is Hep B transmitted?
Blood-borne transmission: horizontal & vertical i.e. sexually transmitted, blood products, mother-to-baby
What is the incubation period of HBV?
Incubation period of 40-160 days (2-6 months)
Is HBV infection acute or chronic?
BOTH
How can Hep B be transmitted in children?
Horizontal transmission – person to person. e.g. In sub-Saharan Africa this can be seen in children who catch it whilst playing in school etc
What chronic hep B infection?
Chronic: viraemia and hepatic inflammation 6 months or more OR persistence of HBsAg for 6 months or more after acute HBV infection
What percentage of people with acute Hep B infection develop a chronic infection?
Adults have a 5-10% chance of developing chronic infection (becoming a chronic carrier). Babies have a 95% chance of developing chronic infection (becoming a chronic
carrier)
What is the molecular organisation of HBV?
It is a DNA Virus. HBV proteins include: core antigen (HBcAg), surface antigen (HBsAg), E antigen (HbeAg) – marker of high infectivity. It has FOUR overlapping reading frames
What is on the surface of HBV?
On the surface, you have surface antigen (HBsAg) forming spears and tubules on surface. Surface antigen is used as a screening test
What drugs for another condition can be used in HBV?
It is a DNA virus, however, it uses reverse transcriptase to replicate so some HIV drugs are effective against HBV.
What happens as a result of the reading frames in HBV overlapping?
Because the reading frames overlap, you may get a mutation in the polymerase gene which may change the surface antigen. This can rarely cause patients to have HBV but not be positive in the surface antigen screening test
What antigen do some patients with HBV have?
Most people with HBV are e antigen positive (HBeAg) which is found in the pre-core part of the core reading frame. Some patients do NOT have HBeAg
What is the role of X antigen in HBV?
Unknown
Can Hep B affect animals?
Yes
What are clinical manifestations of acute hepatitis B in neonates and children?
Mostly asymptomatic or anicteric; 90% HBV-infected neonates develop CHB, and 30% among children age <5 years
What are clinical manifestations of acute hepatitis B in adults?
30-50% icteric hepatitis; 10% become CHB
What is the risk of fulminant hepatitis in HBV?
0.1-0.05% risk of fulminant hepatitis; related to co-infection with HCV/HDV
What are complications of chronic hepatitis B?
Cirrhosis: 8-20% untreated CHB in 5 years.
Hepatocellular carcinoma: the annual risk of 2-5% among CHB cirrhotic patients; affected by host (e.g. alcohol abuse) and viral factors (e.g. high HBV viral load & qHBsAg).
How many people are living with chronic Hep B?
296 million people
CHB-related mortality per year?
Roughly 820,000 people per year
How many cases of HAV infection worldwide?
Approx. 1.5 millions of cases worldwide annually. Developing countries with poor socio-economic conditions
How many cases of HAV per year in the UK?
300-500 cases annually in the UK. Mostly among age 15-34 and travellers. Outbreaks among MSM (2016/17) & IVDU (2001 & 2017).
What are the phases of chronic Hep B?
- HBeAg-positive chronic infection; 2. HBeAg-positive chronic hepatitis; 3. HBeAg-negative chronic infection; 4. HBeAg-negative chronic hepatitis.
In HBV serology, how do you interpret HBsAg, HBsAb, HBcAb, HbeAg, HBeAB?
HBsAg: infection; HBsAb: immunity through either immunisation or past infection; HBcAb: exposure -
IgM: acute infection; HbeAg: replication activity
HBeAB
What would HBV serology show in someone who is susceptible?
HBsAg (-); HBsAb (-); HBc IgM (-); HBcAb (-)
What would HBV serology show in someone who is immune due to past infection?
HBsAg (-); HBsAb (+); HBc IgM (-); HBcAb (+)
What would HBV serology show in someone who is immune due to immunisation?
HBsAg (-); HBsAb (+); HBc IgM (-); HBcAb (-)
What would HBV serology show in someone who has acute hepatitis B?
HBsAg (+); HBsAb (-); HBc IgM (+/-); HBcAb (-)
What would HBV serology show in someone who has chronic hepatitis B?
HBsAg (+); HBsAb (-); HBc IgM (-); HBcAb (+)
What are consequences of HBV?
Hepatocellular carcinoma (HCC) is the most common cancer associated with HBV. It tends to occur in diseased livers. Resection of the tumour alone is unlikely to be a feasible option, because the rest of the liver is likely to be damaged and not functioning very well (therefore transplantation may be considered)