Viral Hepatitis Flashcards
What are the causes of hepatitis?
- Viral
- Non-viral (e.g toxoplasma gondil)
- Drugs (e.g paracetomol)
- Alcohol
- Poisons (e.g aflatoxins, amanita phalloides ‘mushrooms)
- Other (pregnancy, circulatory insufficiency)
What is common amongst Hepatitis viruses (A-E)?
- All are hepatotropic
i. e all demonstrate an ability to infect hepatocytes (liver cells)
What are the stages of viral replication?
- Adsorption
- Penetration
- Uncoating
- Replication of nucleic acid
- Maturation / assembly
- Release
What are the features of HAV?
- Picornaviridae family
- Single-stranded RNA virus
- Non-enveloped virus (naked)
- Only 1 serotype
- Notifiable disease
How is HAV transmitted?
- Faecal-oral route (100m viruses present / gram faeces)
- Poor hand hygiene
- Contaminated food or water
Where are anti-HAV numbers usually high?
Usually developing countries with poor sanitation
What virus can be contained within shellfish?
HAV
What is the incubation period of HAV?
2 - 4 weeks (prodromal phase)
When is HAV excreted in faeces?
1 - 2 weeks before symptoms
How does HAV reach the liver cells?
- Translocation from GI tract to blood
- Infection of liver cells
- Passage to biliary tract to GI tract
- Excretion in faeces
What are the clinical features of HAV?
- Fever, anorexia
- Nausea, vomiting
- Jaundice
- Dark urine, pale stools
- Liver moderately enlarged
- Spleen palpable in 10% patients
- Prognosis excellent (0.1%)
- Death if fulminant hepatic necrosis occurs
How is HAV diagnosed?
Presence of anti-HAV IgM
How is HAV treated?
- No specific treatment
- maintain comfort and nutritional balance
- Fluid and electrolyte replacement
How is HAV prevented?
- Vaccine
- Good hygiene
- Resistant to chlorination
- Killed by boiling for 10 mins
What are the main features of HBV?
- Hepadnaviridae
- Double-stranded DNA virus
- Enveloped virus
What are the HBV antigens?
- HBsAg - surface antigen
- HBcAg - core antigen
- HBeAg - envelope antigen
What antigen indicates high transmissibility?
HBsAg - surface antigen (appears late and provides immunity)
What antigen appears early in infection?
HBcAg - core antigen
What antigen indicates high infectivity?
HBeAg - envelope antigen (derived from core)
How is HBV transmitted?
- Sexual intercourse
- Intra-uterine, peri- and post-natal infection
- Blood or blood products
- Contaminated needles and equipment used by IV drug users
- In association with tattooing, body piercing and acupuncture
- Contaminated haemodialysis equipment
How long is the incubation period for HBV?
2 - 4 months
What percentage of patients with HBV develop liver conditions?
- 50% develop chronic active hepatitis
- 20% of these proceed to cirrhosis
- 1-4% of these risk developing liver cancer
What are the stages of HBV infection?
- Incubation period of 45 - 120 days
- Pre-icteric period of 1 - 7 days
- Icteric period of 1 - 2 months
- Convalescent period of 2 - 3 months in 80-90% of adult cases
What does icteric mean?
Jaundiced
What antibodies are protective against HBV?
- anti-HBs (high HBsAg is what causes chronic infection)
What indicates that HBV infection has become chronic?
Continued presnce of HBsAg and absence of antibodies to it
What do antibodies to core antigen (HBcAg) appear concomitantly with?
Rise in liver transaminases
When do antibodies HBeAg and HBsAg appear?
Only during convalescence
What are the clinical features of the HBV pre-icteric period?
- Malaise
- Anorexia
- Nausea
- Pain in RUQ (tender liver)
What is fulminant hepatitis?
Massive necrosis of liver parenchyma and a decrease in liver size (acute yellow atrophy)
What are the outcomes of acute HBV infection?
- Fulminant hepatitis
- Chronic hepatitis or asymptomatic carrier state
- Resolution of infection
What does the treatment of HBV involve?
- Pegylated interferon (peginterferon): superior compared to alph-interferon alone
- Nucleoside analogues such as oral lamivudine
How is HBV prevented?
- Vaccination: 3 injections over 6 months
- HBV immunoglobulin
- Blood screening
- Needle exchange programmes
- Sexual health education
What are the features of HCV?
- Flaviiviridae
- Single-stranded RNA
- Enveloped virus
How many HCV virus types are there?
6 (from nucleotide sequences)
What are the clinical features of HCV?
- Usually asymptomatic
- Fatigue
- Nausea
- Weight loss
- May rarely progress to cirrhosis
- Small proportion of patients may develop hepatocellular carcinoma many years after primary infection
How is HCV transmitted?
- Blood and blood products
- Blood cantaminated needles
- tatooing, body piercing, acupuncture
- Haemodialysis
Where does HCV replicate?
Mainly in hepatocytes
How long is the HCV incubation period?
2 weeks to 6 months
How is HCV screened?
- Blood test available for HCV based on NAAT
- Current incidence of transfusion-associated HCV is low
How is HCV treated?
- Ribavirin + pegylated alph-interferon
- Combination therapy
- Sofosbuvir (nucleotide analogue)
- Boceprevir (protease inhibitor)
- Telaprivir (nucleotide analogue)
- Daclatasvir (inhibits NS5A)
- No vaccine currently available
What are the features of HDV?
- Small (35nm) circular ss RNA virus
- Defective virus
- HDV picks up HBsAg as it buds from liver cell
- Needs HBV to be dangerous
What specific treatment is available for HDV?
None
What are the features of HEV?
- Caliciviridae
- SS RNA
- Non-enveloped virus
How many cases of HEV are there per year?
20 million
How is HEV spread?
Waterborne disease
Wha is the incubation period of HEV?
3 - 8 weeks
What group are especially at risk of HEV infection?
- Peak incidence in young adults
- Can be life-threatening in pregnant women
- Usually self-limiting in normal patients
What are the 2 types of HEV?
Genotyoe 1 and 2
1 - devloping countries
2 - developed
How is HEV prevented?
- Good sanitation adn hygiene
- Vaccine (Hecolin)
What are the other causes of viral hepatitis?
- Epstein-BArr virus
- Cytomegalovirus
- Yellow fever virus
- Adenoviruses
- Bunyaviruses
- Flaviviruses
