86-88. Viral hepatitis Flashcards
How long does hepatitis need to be present before it becomes chronic?
6 months
Variable changes in liver function
What are the signs of acute hepatitis?
Jaundice, raised AST:ALT, clotting derangement
What are the causes of acute hepatitis?
Infection - bacterial (e.g. leptospirosis) and viral (e.g. hepatitis, syphilis, malaria)
Drugs
Alcohol
Toxins
Autoimmune diseases
Wilsons (genetic; copper builds up in body)
Haemochromatosis
What forms of hepatitis are spread via face-oral route?
Hep A - contaminated water/food - transmitted from person to person (humans are the only reservoir)
Hep E - pork products, minimal person to person transmission
N.B both are RNA viruses
What forms of hepatitis are blood-borne viruses? (transmitted via blood/sex/needles)
Hep B, C, D
List some of the features of HAV
Never chronic
Like flu with jaundice
Sheds via biliary tree into gut
Good immunity after infection
May be spreading the virus before clinical illness shows
Most prevelant in areas of poor public health infrastructure
What are the clinical features of HAV?
Incubation period is about 30 days
Fever, abdominal pain, diarrhoea, jaundice, itch, muscle pains
How is HAV treated?
Usually self-limiting illness (no treatment provided)
Maintain hydration and avoid alcohol
No vaccine given or IgG required
How is HAV diagnosed?
If acute, IgM positive or RNA present in blood or stool
If previously infected or vaccinated, IgG positive
(IgM is produced in new infections, IgG produced if exposed to the infection before)
Give the time periods for the presence of the following factors in HAV:
a) Viraemia
b) HAV in faeces
c) Clinical illness
a) Week 0-6
b) From first few days until week 5
c) From week 2-8
What are the features of the HAV vaccine? Include efficacy, the type of vaccine, and how it gives protection
95% efficacy
Inactivated virus
After 1st vaccine, provides 4 weeks of protection
Lifelong protection after 2nd vaccine
In what circumstances would you give the HAV vaccine?
Travellers, homosexual men, intravenous drug users,
chronic liver disease
In what circumstances would you provide hepatitis A immune globulin (pooled immunoglobulin)? How long does this protection last?
If allergic to the vaccine
If travelling in less than 4 weeks
Lasts 3-6 months
List some of the features of Hep E
Can become chronic
Pregnant women take it badly - high mortality with genotype 1
40 day incubation period
No treatment
Linked to neurological infection
4 genotypes
Similar clinical features to hep A but with added neurological effects in some cases
When is chronic HEV most commonly seen?
In very immunosuppressed patients e.g. bone marrow transplants
What are Hep E neurological manifestations most likely associated with in terms of genotype? What are some of the neurological effects?
Genotype 3
Guillian-Barre syndrome - autoimmune, affects PNS
encephalitis - inflammation of brain
ataxia - affects coordination, balance and speech
Myopathy
What is the result of chronic liver inflammation caused by Hep B?
Liver scarring
Sclerosis
Liver failure/haemorrhage
Hepatoma
Other than needles, blood transmission and sexual fluids, how can HBV be passed on?
Mother to child, child to child
What are the causes of HBV transmission in the tropics?
Vertically or horizontally between children and infected persons
Contact with open sores, scarification, circumcision, bed bugs
NOT mosquitoes
Sexual
Iatrogenic
What are the causes of HBV transmission in the UK?
95% of new diagnoses in the UK are of immigrants infected elsewhere
Many picked up in antenatal screening
New sexual infections in UK are rare
For HBV, what is the:
a) Incubation period
b) Signs and symptoms
a) 2-6 months
b) Fever, fatigue, jaundice, myalgia, joint pains
Bloody ascites, mass in abdomen, cachexia (wasting syndrome), weight loss, abdominal pain
How does HBV infection in children contrast to in adults?
In children, usually asymptomatic but leads to chronic illness
In adults, symptomatic but usually clears
What are the problems associated with chronic HBV?
Death
Cirrhosis
Decompensation
Hepatocellular carcinoma
Describe what the following markers mean with relation to HBV serology
a) sAg
b) sAb
c) cAb
d) eAg
e) eAb
a) Surface antigen - marker of infection (found in infected blood)
b) Surface antibody - marker of immunity (found in those no longer infected/immunised)
c) Core antibody - if positive, they definitely have/have had the virus
d) e antigen - suggests high infectivity
e) e antibody - suggests low infectivity
How is Hep B treated?
No treatment for acute HBV
For chronic, treatment for liver inflammation
small number will clear surface antigen spontaneously
Aim of treatment is not to cure but to suppress viral replication and/or convert from eAg+ to eAb+
What are the immunological ways HBV can be managed?
Pegylated interferon alpha
- increases cellular immune responses
- lots of side effects
Antiviral drugs to suppress replication
- tenofovir
- entecavir
How can HBV be prevented?
Education - safe sex, injecting etc
Screening of pregnant women/doctors
Protect blood supply and hospital supplies
Immunisation
- Active - sAg vaccine to high risk groups in UK
- Passive (HBIG) - in babies with positive mothers/post exposure in the non-immune
What are the 3 ways that babies can be protected from vertical HBV transmission?
What is contraindicated during pregnancy?
- HBV vaccine to all newborns
- HBV immunoglobulin if eAg+ or high VL
- Tenofir during the last trimester if high VL
Peg-IFN
What are the main features of Hep D
Cannot infect without hep B:
Co-infection - hep D and B infect at the same time
Super-infection - hep D infects a patient who already has hep B (more dangerous)
Vertical transmission is rare
Same transmission as hep B
Increases risk of chronic liver disease
Treated with peg-IFN only
What is the most common form of hepatitis worldwide?
What is the most common form UK?
Hep B; Hep C
What % of injecting drug users are infected with hep C?
Over 50%
What are some of the features of hep C?
No vaccine No post-exposure prophylaxis (prevention) No reliable immunity after infection Multiple genotypes (1&3 most common) Most common in Glasgow and drug users
What is the incubation period of hep C?
6-7 weeks
What % of newly infected hep C patients are symptomatic?
25%
What % of HCV patients develop chronic infection and how many clear the infection?
70% chronic; 30% clear
Of those who develop chronic infection, what % develop cirrhosis and what % develop hepatocellular carcinoma?
25%
1-5%
How is HCV diagnosed?
Most are asymptomatic
Most diagnosed through screening of high risk groups
- drug users
- immigrants to UK from high prevalence countries
How is HCV treated?
Pegylated intferon alpha and ribavarin
Overall cure rate of 40-60% after 24-48 weeks of difficult treatment
What are direct acting antivirals (DDAs) used for?
Substantially increase chance of cure
Can eliminate virus by attacking different parts in replication (assembly, replication, receptor binding etc)
In Greater Glasgow and Clyde, regimen decided according to genotype and degree of fibrosis/cirrhosis
Dispensed from community pharmacies with nurse-led treatment clinics in hospital for follow up
Often prescribed with methadone on daily basis
