1. Viral Hepatitis Flashcards
Causes of hepatitis?
Viral (Hep A-E) Non-viral Drugs e.g. paracetamol Alcohol Poisons e.g. Aflatoxins Other e.g. pregnancy, circulatory insufficiency
What do hepatitis viruses A-E all have in common?
All are hepatotropic i.e. are able to infect hepatocytes (liver cells). However are all part of different virus families
6 stages of viral replication?
Adsorption Penetration Uncoating Replication of nucleic acid Maturation/ assembly Release
Hep A Virus: Viral features? Transmission? Shellfish as a source of infection? Stages of infection?
Viral features:
• Picornaviridae family
• Single-stranded RNA virus
• Non-enveloped virus (naked) • Only 1 serotype
Transmission:
– Faecal-oral route
– Poor hand hygiene
– Contaminated food or water
Shellfish as a source of infection:
If water is contaminated with sewage when shellfish filter water, the virus concentrations in flesh. Eating raw or partly cooked shellfish leads to infection
Stages of infection:
• Incubation period of 2-4 weeks leads into prodromal phase (a.k.a pre-icteric stage)
• 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
HAV:
Clinical features?
Treatment?
Prevention?
Clinical features: • Fever, anorexia • Nausea, vomiting • Jaundice • Dark urine, pale stools • No chronic carriage • Presence of anti-HAV IgM
Treatment?
• No specific treatment
• Maintain comfort and nutritional balance
• Fluid and electrolyte replacement
Prevention: • Vaccine • Good hygiene • Resistant to chlorination • Killed by boiling for 10 mins
Hep B Virus:
Viral features?
Antigens?
Viral features:
• Hepadnaviridae
• Double-stranded DNA virus
• Enveloped virus
Antigens:
- HBsAg= Surface antigen. Indicates high transmissibility and provide immunity
- HBcAg= Core antigen
- HBeAg= Envelope antigen. Indicates high infectivity
HBV:
Transmission?
Transmission:
• 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
HBV: Stages of 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
HBV, difference between an acute and chronic infection?
- HBsAg and HBeAg appear during incubation period
- 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
- Continued presence of HBsAg and absence of antibodies to it indicate that infection has become chronic
Chronic: No antibody for surface antigen. Surface antigen levels don’t drop down. Leads to infection
Stages of an acute HBV?
- 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
Clinical features of icteric period of HBV? Cause?
Yellowish pigmentation: Skin, sclerae, other mucous membranes
Caused by hyperbilirubaemia
What does fulminant mean?
Severe and sudden in onset
Clinical outcomes of acute HBV infection?
• Fulminant hepatitis
• Chronic hepatitis or asymptomatic carrier
state
• Resolution of infection
HBV treatment and prevention?
Treatment:
• Pegylated interferon (peginterferon): superior
compared to α-interferon alone
• Nucleoside analogues such as oral lamivudine
Prevention: • Vaccination: 3 injections over 6 months. Against the surface antigen • HBV immunoglobulin • Blood screening • Needle exchange programmes • Sexual health education
Hep C Virus:
Viral features?
Clinical features?
Viral features: • 6 virus types (from nucleotide sequences) • Flaviviridae • Single-stranded RNA • Enveloped virus
Clinical features: • Usually asymptomatic • Fatigue • Nausea • Weight loss • May rarely progresses to cirrhosis • Small proportion of patients may develop hepatocellular carcinoma many years after primary infection
HCV:
Transmission?
Stages of infection?
Transmission: • Blood and blood products • Blood contaminated needles • Tattooing, body piercing, acupuncture • Haemodialysis
Stages of infection:
• Virus replicates mainly in hepatocytes
• Incubation period 2 weeks to 6 months
HCV: Prevention and treatment?
Prevention:
- Screening: Blood test based on NAAT
- No vaccine
Treatment:
- Ribavirin + pegylated alpha-interferon.
- Combination therapy(HAART) : Sofosbuvir, boceprevir, telaprivir, daclatasvir
HBV: Clinical Features of Pre-icteric Period?
- Malaise
- Anorexia
- Nausea
- Pain in right upper quadrant (tender liver)
Hep D Virus:
Viral features?
Viral features:
• Small (35nm) circular single-stranded RNA virus
• Defective virus
• HDV picks up HBsAg as it buds from liver cell (i.e. only comes in co infection with HBV)
HDV: What is function of HBV? Transmission? What increases risk for HDV infection? Treatment?
What is relevance of HBV:
• Found as co-infection with HBV
• HBV serves as helper virus for infectious HDV production
Transmission: Percutaneously, sexually, from infected blood
What increases risk for HDV infection: Chronic HBV carriers are at risk for infection with HDV
Treatment: None
Hep E Virus: Viral features? Incidence? Transmission and symptoms? Prevention?
Viral features:
• Caliciviridae
• Single-stranded RNA
• Non-enveloped virus
Incidence: Young adults. Can be life-threatening in pregnant woman
Transmission and symptoms: • Waterborne disease • Incubation period 3-8 weeks • Usually self-limiting • Signs and symptoms are similar to other acute forms of hepatitis
Prevention:
• Good sanitation & hygiene
• Vaccine (Hecolin)
6 other causes for viral hepatitis?
- Epstein-Barr virus
- Cytomegalovirus
- Yellow fever virus
- Adenoviruses
- Bunyaviruses
- Flaviviruses
