Viral Hepatitis Flashcards
What does IgM show?
Acute/recent infection, or from donated blood
What does IgG show?
Past infection, immunisation response, presence of passively acquired antibody after receiving blood products
What is hepatitis?
Inflammation of liver
What are differential diagnoses of viral hepatitis?
- CMV and EBV (can cause a hepatitis)
- Parvovirus, adenovirus, enterovirus (can present with hepatitis instead of normal rash e.g. due to adenoviraemia)
- Yellow fever, dengue
Which Hep viruses don’t cause chronic infection?
Hep A and E (can in immunocompromised)
Which Hep viruses cause chronic infection and cirrhosis?
B (± D) and C
What conditions are chronic Hep B and C infections associated with?
- Persistent infection (carrier)
- Chronic liver disease
- Chronic active or persistent hepatitis
- Cirrhosis
- Hepatocellular carcinoma
What is cirrhosis?
When the liver is no longer functioning properly, small and shrunken
What investigations are done for viral hepatitis?
1) LFTs
2) Serology - antigen, IgM, IgG, alpha fetoprotein
3) Molecular - esp. when looking at prognosis and response to anti-viral agents
4) Imaging - fibroscan and ultrasound
5) Histopathology - liver biopsy (depending on other results)
What will LFTs show in hepatitis?
High aminotransferases (AST and ALT) in low 1000s and high BR
What does the presence of alpha fetoprotein indicate in chronic infection?
Hepatocellular carcinoma
What does imaging show in viral hepatitis?
Liver fibrosis, fatty deposits, general composition
What does a liver biopsy allow you to do?
Look at liver structure
What are the signs and symptoms of viral hepatitis?
- Malaise, fever, headaches
- GI symptoms (anorexia, N&V)
- Right upper quadrant abdominal pain (liver capsule inflamed, liver enlarged and stretched)
- Dark urine (can’t eradicate bilirubin) and clay coloured faeces (no bilirubin)
- Jaundice
What are treatments for viral hepatitis?
- Antiviral agents
- Immunomodulation e.g. interferon
- Supportive
- Passive immunity through blood products containing IgG to virus to neutralise virus (temporary)
What are 3 similarities between Hep A and E?
1) Faecal-oral transmission
2) Similar incubation period
3) Same methods used for lab diagnosis
What is the incubation period of Hep A?
3-5 weeks
What is the transmission route of Hep A?
Faeco-oral transmission (source outbreaks, person to person)
How do you diagnose acute Hep A infection?
Hep A IgM detection in blood
When are people with Hep A considered infectious?
2 weeks before to 7 days after jaundice onset
What is the incubation period of Hep E?
6 weeks
How is Hep E transmitted?
Faeco-oral, also undercooked meat products
How do you diagnose Hep E infection?
Hep E IgM in blood and RNA detection
What are similarities between Hep B, D and C?
1) Persistent infection
2) Diagnostic tests similar - serology and molecular
3) Management of chronic infection - antivirals, immunomodulators
What is the incubation period of Hep B?
6 weeks-6 months
How is Hep B similar to HIV?
It has a reverse transcriptase component
How much Hep B do you need to be infectious?
Nano amount
What does the soluble core of the virus contain that is associated with high infectivity?
e antigen (HBeAg)
How is Hep B transmitted?
1) Sexual intercourse
2) Blood and blood products
3) Injecting drug use
4) Tattoos
5) Body piercing
6) Acupuncture
What is a carrier of Hep B?
Someone who has had the virus for 6 months
How long does Hep B surface antigen (HBsAg) persist in the circulation for?
> 6 months
What are the two possible clinical states after acute infection?
1) Icteric (infection resolves), develop jaundice
2) Anicteric (carrier state) - don’t develop jaundice, cirrhosis, hepatocellular carcinoma
What is the level of HBsAB in acute, resolving and chronic infection?
< 10 mIU/ml
What is the level of HBsAB in past infection or vaccine response?
> 10 mIU/ml
What do you find in serology tests in acute infection?
HBsAg, HB core antibody, HB core IgM, HB e antigen
What do you find in serology tests in chronic infection?
HBsAg, HB core antibody ± HB e antigen/antibody
Why do you look for HBsAg in Hep B infection?
Want to neutralise it, showing specificity
Why is molecular diagnosis of HBV DNA superior?
- Most direct measure of HBV replication
- Clinical staging of chronic infection
- Assessment of infectivity
- Efficacy of antiviral agents
What are the 4 risk groups for chronic infection?
1) Infection early in life
2) Asymptomatic
3) Immune system defect
4) Male gender
How is Hep B prevented?
1) Passive immunisation - Hep B immunoglobulin given to babies at birth whose mothers have Hep B on top of vaccine
2) Active immunisation - recombinant vaccine
How is Hep B treated?
1) Antiviral therapy
2) Immunomodulators (SC injection)
What type of virus is Hep D?
Satellite virus
Why does Hep D need Hep B to replicate and cause infection?
- ssRNA virus enveloped by HBsAg so needs it to multiply
- Can only infect people in HBsAg is around
What is Hep D infection?
- Superinfection of Hep B
- Acute infection is self limiting bc cannot survive without HBsAg
What else is Hep B immunisation protective against?
Hep D and arguably liver cancer bc Hep B is a big cause of liver cancer
What are the routes of transmission of Hep C?
1) Injecting drug users sharing equipment
2) Blood and blood products
3) Contaminated needles e.g. tattoos, acupuncture, body piercing
(sex and MTC lower risk of transmission)
What is the incubation period of Hep C?
6-12 weeks
What are the clinical features of Hep C?
- Anicteric (75%), carrier state, 40-50% chronic liver damage
- 25% icteric (jaundiced)
- LFTs may be much lower than Hep B
- 20% cirrhosis
- Hepatocellular carcinoma
Why is Hep C hard to diagnose?
Most of the time no jaundice and LFTs lower (so screening v important)
How is Hep C diagnosed?
- Serology - HCV antibody
- Molecular - HCV RNA detection and quantification, HCV genotype, antiviral resistance
Is there a vaccine for Hep C?
No (would need to be 6-valent bc 6 genotypes)
Describe treatment of Hep C with antivirals
- Goal is to cure infection and prevent complications (can eradicate bc not in chromosome like Hep B)
- Aim is undetectable HCV RNA in blood by 12 weeks
- Cure rates > 90%
- Directly acting antivirals (DAA)
- Target HCV protease and other viral proteins
Which is the only hepatitis virus which is not ssRNA?
Hep B (dsDNA)
Describe Hep A
- Self limiting in 99%
- No chronicity
Is there a vaccine available for Hep A?
Yes
What indicates previous exposure to Hep A?
Hep A IgG
Do you treat everyone with Hep B?
No - there are different phases
When do you treat Hep B?
If ALT and viral load is elevated
Why do you treat Hep B?
To prevent complications
What is the natural course of Hep C?
Acute Hep C → chronic Hep C → cirrhosis → liver cancer/hepatic failure
What drug can cure Hep C without interferon?
Sofosbuvir
What can chronic viral infections (e.g. Hep C) be treated with to stimulate the immune system?
IFN-alpha (interferon, cytokine)
