Viral Causes of Hepatitis Flashcards
What viral family is HAV?
Picornavirus
What viral family is HEV?
Hepevirus
What viral family is HBV?
Hepadnavirus
What viral family is HCV?
Flavivirus
What is the transmission route of HAV?
Fecal-oral
What is the transmission route of HEV?
fecal-oral
What is the transmission route of HBV?
Parenteral
What is the transmission route of HCV?
Parenteral
What viruses other than hepatitis viruses cause liver infections? (6)
Epstein barr CMV Rubella Mumps ECHO viruses Yellow Fever
What is the structure of HAV?
icosahedral capsid that is enveloped in faeces and can be enveloped or non-enveloped in blood
Why is HAV enveloped in the blood but non-enveloped in the environment?
Budding allows for exit without lysis, immune escape in the body - confers resistance to neutralising antibodies,
no envelope outside the body in faeces confers stability and transmission of virus
How many serotypes does HAV have?
one serotype based on structural proteins VP1 and VP3
How many genotypes of HAV are there?
4 genotypes in humans (1, 2, 3, 7)
3 genotypes in monkeys (4, 5, 6)
HAV genomic RNA is translated into a. . ?
polyprotein which is cleaved into structural proteins and replicative proteins
How does HAV infection spread through the body?
HAV enters via the oral cavity, crosses the intestines and enters the blood where it can spread to the liver, enter the bile and enter the stool
What is the incubation period for hepatitis A?
2-6 weeks
What are the symptoms during the prodromal phase of HAV infection (1-7 days)? (7)
- Fever
- Fatigue
- Malaise
- Loss of appetite
- abdominal pain
- nausea
- vomiting
What are the symptoms of the symptomatic phase of HAV infection? (3 weeks) (4)
- Bilirubinuria
- Pale/clay coloured faeces
- Jaundice
- Liver enlargement
What are the complications of HAV infection? (3)
- cholestatic hepatitis
- relapsing hepatitis
- fulminant hepatic failure
How does HAV cause liver damage?
Immunopathology mediated liver damage
Cytotoxic T cells
What are the characteristics of HAV in regions of high endemicity? (2)
- disease rates are low as most people are infected at an age when infection is asymptomatic
- transmission mainly from person to person but also contaminated food/water
What are the characteristics of HAV in regions of intermediate endemicity? (2)
- disease rates are high as the age of infection is older
2. person to person transmission and large common source outbreaks
What are the characteristics of HAV in regions of low endemicity? (2)
- disease rates are low due to lack of exposure but large numbers of children and adults are susceptible
- person to person and occasionally food/water transmission
What are the characteristics of HAV in regions of very low endemicity?
- disease is limited to adults in defined risk groups such as international travellers
How is HAV diagnosed in a lab? (2)
- liver function tests eg ALT
- Serology
IgM anti-HAV
Total anti-HAV
How can HAV be prevented?
- improved standards of hygiene and sanitation
- immunization
passive - immune serum globulin
active - inactivated whole virus vaccines
What is the host range of HEV genotype 1 and 2?
Humans
What is the host range of HEV genotype 3?
Human
Pig
Rabbit
Deer
What is the host range of HEV genotype 4?
Human
Pig
What is the host range of HEV genotype 5 and 6?
Wild boar
What is the host range of HEV genotype 7?
Camel
What happens to HEV’s envelope?
Non-enveloped in the faeces, enveloped in the body
What is HEV’s genome?
positive sense ssRNA
What is the incubation period for HEV?
2-6 weeks
What type of infection can HEV cause? (3)
- asymptomatic
- icteric
- fulminant
What are the symptoms of HEV? (6)
- fever
- nausea
- abdominal pain
- jaundice
- long periods of viraemia
- faecal shedding
What is the mortality rate of pregnant women infected with HEV1 and HEV2?
20-25% mortality rate
What genotypes of HEV cause chronic infections in immunocompromised people?
HEV3 and HEV4
What are neurological complications of infection with HEV1 and acute and chronic HEV3? (4)
- Guillain-Barre
- Bell’s Palsy
- Acute transverse myelitis
- Acute meningoencephalitis
What are renal complications of HEV infection?
membranoproliferative glomerulonephritis (MPGN)
What are the muscular complications of HEV infection? (2)
- athralgia
2. myalgia
What are the haematological complications of HEV infection? (2)
- thrombocytopaenia
2. aplastic anaemia
What is the route of transmission of HEV1 and HEV2?
Faecal oral route in developing countries
What is the route of transmission of HEV3 and HEV4?
zoonotic transmission in developed countries
Which HEV genotype can be transmitted via blood?
HEV3
Which HEV genotype can be transmitted vertically from mother to child?
HEV1
How is HEV diagnosed in a lab?
serology - anti-HEV IgM
How can HEV be prevented?
improved sanitation
two commercial vaccines
How many genotypes of HBV are there?
HBVA-J (10)
What are the transmission routes of HBV? (3)
- Blood and Blood products
- Sexual contact
- Perinatal
What is the main mode of transmission of HBV in regions of high endemicity?
perinatal transmission
What is the main mode of transmission of HBV in regions of medium endemicity?
childhood and percutaneous transmission
What is the main mode of transmission of HBV in regions of low endemicity?
adult, sexual and percutaneous transmission
What are the HBV proteins? (4)
- S - surface proteins (HBsAg)
- C - core proteins (HBeAg, HBcAg)
- P - polymerase, reverse transcriptase
- X - HbX
What percent of adults have complete recovery from HBV within 1-3 months?
95%
What is the incubation period of HBV?
1-4 months
What are the characteristics of the immune tolerant phase (phase 1) of HBV infection? (4)
- HBeAg+
- High HBV DNA
- ALT normal
- Minimum or no inflammation
What are the characteristics of the immune active/clearance phase (phase 2) of HBV infection? (4)
- HBeAg+
- High/declining HBV DNA levels
- ALT high
- moderate to severe liver inflammation
What are the characteristics of the inactive phase (phase 3) of HBV infection? (5)
- HBe negative/anti-HBe positive
- ALT levels normal
- Low HBV DNA
- minimum inflammation in liver
- low risk of cirrhosis or HCC
What are the characteristics of the reactivation phase (phase 4) of HBV infection?
- HBe negative/ anti-HBe positive
- High HBV DNA and ALT levels
- Inflammation and fibrosis
- pre core mutations
increased risk of cirrhosis is associated with which HBV mutant?
HBe negative HBV mutant
What are the characteristics of occult HBV (phase 5)?
- unexplained liver disease in HBsAg negative, anti-HBc positive
- normal ALT levels
- detectable HBV DNA in blood or liver by sensitive molecular methods
How can severity of HBV liver disease be assessed through biochemical parameters? (7)
- liver enzymes
- alkaline phosphatase
- bilirubin levels
- albumin levels
- gamma globulins
- full blood count
- prothrombin time
How can severity of HBV liver disease be assessed through physical examination? (3)
- abdominal ultrasound is recommended for all patients
- liver biopsy
- transient elastography
What are the indications for treatment of chronic HBV?
- serum HBV levels > 2000 IU/mL
- Serum ALT levels > ~40 IU/mL
- moderate necroinflammation and/or moderate fibrosis or cirrhosis
What are the treatment strategies for HBV? (2)
- pegylated interferon
2. nucleoside analogues: lamivudine, entecavir, tenofovir
How is HBV monitored?
- HBV viral load assays
- genotyping assays
- drug resistance mutation assays
- liver enzymes
- serology for HBeAg and anti-HBeAg
How is an acute infection of HBV diagnosed?
IgM and anti-HBcAg
How can HBV be prevented?
vaccination
How can vertical transmission from mother to child be prevented?
HB Ig and vaccine should be given to infants born to HBV positive mothers
How many different genotypes of HCV are there
7 genotypes 1-7
What are the clinical manifestations of acute HCV?
- malaise
- nausea
- dark urine
- jaundice
What is the incubation period of acute HCV?
7 weeks
What percentage of HCV infections become chronic?
50-80%
What percentage of chronic HCV infections become cirrhosis?
20%
What are the skin complications of HCV infection? (2)
- porphyria cutanea tarda
2. lichen planus
What are the renal complications of HCV?
- membranoproliferative glomerulonephritis (MPGN)
What are the haematological complications?
cryoglobulinaemia
What are the CNS complications of HCV infection?
Depression
What are the neuromuscular complications of HCV infection? (2)
- arthritis
2. peripheral neuropathy
What are the vascular complications of HCV infection?
polyarteritis nodosa
What does “sustained virological response” mean?
refers to the absence of HCV RNA in serum 12 weeks after stopping treatment
What does “non-responder” refer to?
people in whom HCV RNA levels remain stable during treatment
What does “rapid virological response” mean?
undetectable HCV RNA at 4 weeks
What does “early virological response” refer to?
undetectable HCV RNA at 12 weeks
How is HCV diagnosed?
serology
ELISA measures antibodies against NS4, core, NS3, NS5
6-8 weeks after exposure
How is HCV monitored?
viral load