Viral Hepatitis Flashcards
Identify the main causes of hepatitis, and the pathogens involved with each.
• Viral • Non-viral e.g. Toxoplasma gondii • Drugs e.g. paracetamol • Alcohol • Poisons e.g. Aflatoxins e.g. Amanita phalloides (mushrooms) • Other e.g. Pregnancy e.g. Circulatory insufficiency
Define hepatotropic. Which of the hepatitis viruses are hepatotropic ?
Demonstrate an ability to infect hepatocytes (liver cells)
All of them (A through E)
Identify all the main hepatitis viruses.
Hepatitis A (HAV) Hepatitis B (HBV) Hepatitis C (HCV) Hepatitis D (HDV) Hepatitis E (HEV)
Which family do the hepatitis viruses belong to ?
All belong to different virus families (i.e. all possess entirely different properties)
Identify the main stages of viral replication.
- Adsorption
- Penetration
- Uncoating
- Replication of nucleic acid
- Maturation / assembly
- Release
HEPATITIS A
- Family
- Structure
- Number of serotypes
HEPATITIS A -Family: Picornaviridae family -Structure: Single-stranded RNA virus Non-enveloped virus (naked) -Number of serotypes: only 1 serotype
How does transmission of Hep A occur ?
• Spread by:
– Faecal-oral route
– Poor hand hygiene
– Contaminated food or water
What is the number of Hep A viruses present per gram of feces ?
100 million viruses present /gram faeces
How does shellfish lead to transmission of Hepatitis A virus ?
- Sewage contaminated water
- Filter action of shellfish leads to concentration of virus in flesh
- Harvested shellfish carry high numbers of viruses
- Eating raw or partly cooked shellfish leads to infection
Identify the main stages of HAV infection.
- Incubation period of 2-4 weeks (prodromal phase)
- Virus excreted in faeces for 1-2 weeks before symptoms
- Translocation from GI tract to blood
- Infection of liver cells
- Passage to biliary tract and back to GI tract
- Excretion in faeces
Identify the main clinical features of HAV.
- Fever, anorexia
- Nausea, vomiting
- Jaundice
- Dark urine, pale stools
- Liver moderately enlarged
- Spleen palpable in 10% patients
- No chronic carriage
- Diagnosed by presence of anti-HAV IgM
- Prognosis excellent (mortality 0.1%) in young adults
- Death if fulminant hepatic necrosis occurs
Describe the treatment of HAV.
- No specific treatment
- Maintain comfort and nutritional balance
- Fluid and electrolyte replacement
Describe prevention of HAV.
• Vaccine
• Good hygiene
(Resistant to chlorination)
• Killed by boiling for 10 mins
HEPATITIS B
- Family
- Structure
HEPATITIS B -Family: Hepadnaviridae -Structure: • Double-stranded DNA virus • Enveloped virus
Identify the main antigens involved with Hepatitis B, and explain their significance.
• HBsAg - surface antigen
– Indicates high transmissibility
– HBsAb provides immunity and appears late (not in carriers)
• HBcAg – core antigen
– HBcAb appears early in infection
• HBeAg - envelope antigen
– Derived from core
– Indicates high infectivity
How does transmission of Hepatitis B occur ?
- Sexual intercourse
- Intra-uterine, peri- and post-natal infection
- Blood or blood products
- Contaminated needles and equipment used by intravenous drug users
- In association with tattooing, body piercing and acupuncture
- Contaminated haemodialysis equipment
Who is at risk of Hepatitis B infection ?
• Anyone coming into contact with blood / body fluids from someone infected with HBV
• At greatest risk are those who:
– Have sex with an infected person
– Have multiple sex partners
– Have a sexually transmitted infection
– Are men who have sex with men
– Inject drugs or share needles, syringes, or other drug equipment
– Live with a person who has chronic hepatitis B
– Are infants born to infected mothers
– Are exposed to blood / body fluids in their job
– Are hemodialysis patients
– Stay for a prolonged period of time in areas of the world with moderate to high rates of hepatitis B
Identify the main stages of HBV infection.
• Incubation period of 2-4 months
• 50% patients develop chronic active hepatitis
- 20% of these proceed to cirrhosis
1-4% of these risk developing liver cancer
Identify the main stages of HBV acute infection, and state how long each one lasts.
- Incubation period of 45 – 120 days
- Pre-icteric (preceding appearance of jaundice) period of 1 – 7 days
- Icteric period of 1 – 2 months
- Convalescent period of 2 – 3 months in 80-90% of adult cases
Describe the evolution of levels of Hepatitis B antigens, and of antibodies to those antigens, in both acute, and chronic hepatitis.
ACUTE HEPATITIS
• HBsAg and HBeAg appear during incubation period (then levels go back down)
• Viral DNA becomes detectable
• Antibodies to core antigen (HBcAg) appear concomitantly with rise in liver transaminases
• Antibodies to HBeAg and HBsAg only appear during convalescence
CHRONIC HEPATITIS
• Continued presence of HBsAg and absence of antibodies to it indicate that infection has become chronic
Describe the clinical features of the
1) Pre-icteric Period of HBV
2) Icteric Period
1) Pre-icteric period • Malaise • Anorexia • Nausea • Pain in right upper quadrant (tender liver)
2) Icteric period • Yellowish pigmentation (caused by hyperbilirubaemia) – Skin – Sclerae – Other mucous membranes
Identify the clinical outcomes of acute HBV infection.
• Fulminant hepatitis (“patient’s condition rapidly deteriorates, with hepatic encephalopathy, necrosis of the hepatic parenchyma, coagulopathy, renal failure, and coma”)
• Chronic hepatitis or asymptomatic carrier
state
• Resolution of infection
Describe the treatment for HBV.
• Pegylated interferon (peginterferon): superior
compared to α-interferon alone
• Nucleoside analogues such as oral lamivudine
Describe the prevention for HBV.
- Vaccination: 3 injections over 6 months
- HBV immunoglobulin (prophylactic drug)
- Blood screening
- Needle exchange programmes
- Sexual health education
HEPATITIS C
- Family
- Structure
- Number of genotypes
HEPATITIS C -Family: Flaviviridae -Structure: • Single-stranded RNA • Enveloped virus -Number of genotypes: 6 virus types (from nucleotide sequences)
Identify the main clinical features of HCV infection.
- Usually asymptomatic
- Fatigue
- Nausea
- Weight loss
- May rarely progresses to cirrhosis
- Small proportion of patients may develop hepatocellular carcinoma many years after primary infection
How does HCV transmission occur ?
- Blood and blood products (current incidence of transfusion-associated HCV is low)
- Blood contaminated needles
- Tattooing, body piercing, acupuncture
- Haemodialysis
Describe the main stages of HCV infection.
- Virus replicates mainly in hepatocytes
* Incubation period 2 weeks to 6 months
Which of the hepatitis viruses can we screen for ? How so ?
Hepatitis C
Blood test available for HCV based on NAAT
Describe the treatment for HCV.
INTERFERON
- Reduces liver transaminases in 80% of patients
- Ribavirin works well in combination with pegylated α-interferon
COMBINATION THERAPY -Often one of these in addition to ribavirin and pegylated α-interferon Sofosbuvir (nucleotide analogue) Boceprevir (protease inhibitor) Telaprivir (nucleotide analogue) Daclatasvir (inhibits NS5A)
How is prevention of Hep C achieved ?
- No vaccine currently available
* Preventing transmission
HEPATITIS D
-Structure
HEPATITIS D
-Structure:
Small (35nm) circular single-stranded RNA virus
HDV picks up HBsAg as it buds from liver cell
Define a defective virus. Which of the hepatitis viruses is a defective virus ?
“Viruses which lack a complete genome so that they cannot completely replicate or cannot form a protein coat.”
Hepatitis D
HDV
- Transmission
- Risk factors for infection
- Treatment
HDV
-Transmission: Transmitted percutaneously, sexually, from infected blood
- Risk factors for infection: Chronic HBV carriers are at risk for infection with HDV (HDV is found as co-infection with HBV; HBV serves as helper virus for infectious HDV production)
- Treatment: No specific treatment is available
HEPATITIS E
- Family
- Structure
HEPATITIS E -Family: Caliciviridae -Structure: • Single-stranded RNA • Non-enveloped virus
How does HEV transmission occur ?
• Waterborne disease
Describe the epidemiology of HEV.
• Peak incidence in young adults
State the incubation period, signs and symptoms of HEV infection.
HEV
- Incubation period 3-8 weeks (but HEV usually self-limiting)
- Signs and symptoms are similar to other acute forms of hepatitis (BUT can be life-threatening in pregnant woman)
Describe prevention of HEV infection.
- Good sanitation and hygiene
* Vaccine (Hecolin)
Identify other viruses (besides the hepatitis viruses) which can cause viral hepatitis.
- Epstein-Barr virus
- Cytomegalovirus
- Yellow fever virus
- Adenoviruses
- Bunyaviruses
- Flaviviruses
