Viral Hepatitis Flashcards
What is the definition of acute and chronic hepatitis
Acute - Usually symptomatic with deranged LFTs (raised ALT and AST)
Chronic - When hepatitis virus presents for more than 6 months. Usually is asymptomatic
What are the routes of transmission for the different hepatitis viruses
A and E - Faecal oral route
B, C and D - Blood borne
What are the infectious and non infectious causes of acute hepatitis?
Infectious - Hepatitis viruses, EBV, CMV, toxoplasmosis, leptospirosis, Q fever, syphilis, malaria.
Non infectious m- Toxins, drugs, alcohol, autoimmune, Wilsons and haemochromatosis
What are the different laboratory diagnostic techniques for viral hepatitis?
Direct detection of the immune response via IgM or IgG.
Viral nucleic acid detection (RNA or DNA) or antigen detection (HBV and HCV)
What are the features of Hepatitis A?
RNA virus transmitted via faeco-oral route. Incubation period is 2-4 weeks. NO chronic carriage.
Age is the main determinant of severity. Most children are asymptomatic.
Self limiting illness with no treatments however good immunity after infection/vaccination
Explain the diagnosis of hepatitis A
In an acute infection patient will be IgM positive or have HAV RNA in blood/stool.
IN a previous hep A/vaccinated patient IgG will be detected
IgM and/or IgG against HAV
Describe features of the hepatitis A vaccine
- Inactivated virus which gives life long immunity after 2 doeses. Given to travellers, MSM, IVDU or chronic liver diseases.
When is hepatitis A immune globulin used?
If patient is vaccine allergic or if there is less than 4 weeks till travel. It offers 3-6 months of immunity. It is pooled immunoglobulin
Describe features of hepatitis E
RNA virus transmission occurs via faeco-oral route or contaminated pork products. Incubation period is 40days. 4 genotypes with most common being GT3.
Treatment is supportive, no vaccine and chronic hep E only in immunocompromised High mortality in pregnancy
What are the complications of a Hepatitis E infection?
Neurological complications which are associated with genotype 3. These include:
- Guilliane barre syndrome,
- Encephalitis,
- Ataxia,
- Myopathy
Describe features of hepatitis B and its routes of transmission
DNA virus which causes around 2million deaths per year. However is vaccine preventable.
Transmission occurs via - Mother to baby (most common), contaminated needles/syringes, child to child, organs and tissue transplants, bodily fluids or transfusion of blood products.
Describe features of acute hepatitis B infections
Incubation is 2-6months. Age at time of infection determines severity and risk of developing chronic hepatitis B. Infection at young age is likely to be asymptomatic but high risk of chronic. Infection at old age is likely to be symptomatic but not chronic
What are the complications of a hepatitis B infection
Chronic HBV which can cause:
- Cirrhosis,
- Decompensation,
- Hepatocellular carcinoma (can present with weight loss, abdo pain, fever, cachexia, bloody ascites, jaundice),
- Death
What are the laboratory tests in hepatitis B?
sAg (surface antigen) - marker of active infection.
sAb (Surface antibody) - marker of immunity.
cAb (core antibody) - present in anyone who has had active infection, negative in vaccination.
eAg (e antigen) suggests high infectivity.
eAb (e antibody) suggests low infectivity.
What are the two groups of chronic hepatitis B infections
eAg positive (early disease) - there will be a high viral load, high risk of chronic liver diseases and hepatocellar carcinoma and highly infectious.
eAg negative (late disease) - there will be low viral load, lower risk of CLD/HCC and less infectious.
What is the treatment for acute hepatitis B?
None. Infection usually resolves on its own
What is the treatment for chronic hepatitis B?
- None unless patients shows liver inflammation or fibrosis. In which case treatment is suppression of viral replication via: interferon (immuno-modulatory) or tenofovir/entecavir (Supress viral replication)
What are the prevention methods for hepatitis B?
- Education,
- Immunisation (HBV sAg vaccine)
- Prevention of mother to child transmission. If mother is positive then baby is given HBV vaccine in first 24hours of life and 6 total in first year. If mum has high viral load then given HBV immunoglobulin (if eAg +) or tenofovir in 3rd trimester.
Describe features of hepatitis D
Can only be acquired if co-infected with HBV sAg positive, as HDV requires HBV to replicate.
Infection increases risk of chronic liver disease. Treatment is via interferon only (bulevirtide maybe)
Describe features of hepatitis C
- RNA virus transmitted via injecting drugs, transfusions/transplants and rarely sexual.
There is no reliable immunity after infection, no vaccine or prophylaxis. - Incubation is 6-7 weeks. Around 30% clear the infection and 70% go on to develop chronic infections.
Explain the diagnosis of hepatitis C
- Most diagnoses occur by screening high risk groups (IVDU or immigrants)
- Anti HCV IgG positive means chronic infection or cleared infection. Whereas PCR or antigen positive means a current infection.
Explain the treatment of hepatitis C
Direct Acting Antivirals (DAAs) inhibit different stages of the replication cycle. Can cure almost everyone within 8-12 weeks of oral treatment.
Regimen of treatment is according to genotype and degree of cirrhosis.
