Week 5 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
- List the causes of release of erythropoietin by the kidneys.
High altitudes
Haemorrhage
Red blood cell destruction
Increased tissue oxygen demands
The ability of RBCs to carry O2 determines the release of erythropoietin
- List the functions of erythropoietin.
Sustains red blood cell production
Stimulates bone marrow cell that are committed to becoming red blood cells.