Hepatitis A and E Flashcards
Hepatitis A virus
(a) Family
(b) Genus
(c) Genome type
(d) Number of serotypes, genotypes
(e) Enveloped/Non-enveloped?
(f) Transmission
(a) Family: Picornaviridae
(b) Genus: Hepatovirus
(c) Genome type: positive sense single-stranded RNA virus
(d) Number of serotypes, genotypes: 1, 6
(e) Enveloped/Non-enveloped? Non-enveloped
(f) Transmission: feco-oral [may also be transmitted sexually]
What are some risk factors that may increase the probability of HAV infection?
🩺 Contaminated food and water
🩺 Close personal contact with HAV-infected persons
🩺 Institutionalization (e.g., prisoners, day care)
🩺 Occupation (daycare, prison guards, lab techs)
🩺 Male homosexuality
🩺 PWIDS (People who inject drugs)
Briefly discuss the pathogenesis of Hepatitis A.
🛸 HAV is primarily transmitted through ingestion of contaminated food or water, or through direct contact with an infected person’s faeces.
🛸 After entering the body, HAV is believed to replicate in the mucosal cells of the intestines [enterocytes].
🛸 The virus attaches to liver cells (hepatocytes) using a receptor called HAVCR (Hepatitis A Virus Cellular Receptor) and replicates within these cells.
🛸 HAV does not directly destroy liver cells. Instead, it replicates within them without causing immediate cell death.
🛸 The liver damage seen in Hepatitis A is primarily due to the body’s immune response. Cytotoxic T-cells attack the infected hepatocytes, leading to inflammation and liver damage.
🛸 The virus is released into the bloodstream (viremia) and bile. It is then excreted in the feces, which can contaminate food and water, continuing the cycle of transmission.
Further notes:
â—¾ HAVCR1 is also known as TIM-1 (T-cell Immunoglobulin and Mucin Domain 1). It is a type I transmembrane glycoprotein.
â—¾ It serves as a receptor for several viruses, including hepatitis A virus, Ebola virus, and dengue virus.
It is involved in regulating immune cell activity, particularly in response to viral infections.
â—¾ HAVCR1 is also known as Kidney Injury Molecule-1 (KIM-1) and is highly upregulated in injured kidneys.
â—¾ It is expressed in various tissues, including the kidneys, liver, lungs and immune cells.
Briefly discuss the clinical presentation of HAV infection.
🩺 Incubation period: 2-4 weeks
🩺 Asymptomatic phase: HAV infection may be asymptomatic, and especially in children
🩺 Prodrome phase: non-specific symptoms e.g. fever, nausea, anorexia, fatigue, headache, and general malaise
🩺 Icteric phase: jaundice, pain in the upper right quadrant of the abdomen, dark-colored urine, pruritus [itching due to bile salts deposited in the skin]
Although rare, Hepatitis A infection can cause fulminant hepatitis. What is fulminant hepatitis?
Fulminant hepatitis is a severe and rapid form of liver failure that develops within days or weeks. Early symptoms include fatigue, nausea, and stomach discomfort. Advanced symptoms include jaundice, confusion, encephalophathy [due to build up of toxins which the liver normally clears], sleepiness, personality changes and easy bruising.
What are primary tests in the diagnosis of HAV infection?
(1) HAV IgM Antibodies (ELISA) [a positive result indicates a recent or current HAV infection]
(2) HAV RNA (RT-PCR)
Why isn’t the presence of IgG antibodies taken as evidence for a current or recent HAV infection?
✔ IgM antibodies are produced first and indicate a recent or current infection. They appear early in the course of the infection and are the primary marker for actute Hepatitis A.
✔ IgG antibodies develop later and remain in the body for life, indicating past infection or immunity (from previous infection or vaccination).
treatment of Hepatitis A
treatment is supportive
List prevention measures against Hepatitis A.
(a) Adequate, safe drinking water
(b) Proper disposal and treatment of waste
(c) Personal hygiene
(d) Vaccination
What type of vaccine is the Hepatitis A vaccine?
Inactivated vaccine
Hepatitis E virus
(a) Family
(b) Genome type
(c) Number of serotypes, genotypes
(c) Enveloped/Non enveloped?
(d) Transmission
(a) Family: Hepeviridae
(b) Genome type: positive-sense, single-stranded RNA genome
(c) Number of serotypes, genotypes: 1, 8
(c) Enveloped/Non enveloped? Non-enveloped
(d) Transmission: fecal-oral route
HEV pathogenesis
🛸 HEV enters the body through the fecal-oral route, typically via contaminated water or food. It initially replicates in the gut mucosa.
🛸 The virus then spreads to the liver where it attaches to hepatocytes using specific receptors.
🛸 HEV replicates within hepatocytes. Unlike some viruses, HEV is non-cytolytic.
🛸 The liver damage seen in HEV infection is primarily due to the immune response. Cytotoxic T-cells attack the infected hepatocytes, leading to inflammation and liver damage.
🛸 The virus is released into the bloodstream and bile, eventually being excreted into the faeces.
[Symptoms are similar to HAV.]
Further notes:
HEV has been shown to utilize claudin-1 and occludin, which are tight junction proteins found on the surface of hepatocytes.
Hepatitis A and E have similar transmission routes, except for one key difference…
HEV can be acquired via zoonotic transmission.
Compare HAV and HEV in terms of severity and chronicity.
HAV: Typically causes acute, self-limiting hepatitis and does not lead to chronic infection.
HEV: Can cause acute hepatitis, but in some cases, especially in immunocompromised individuals, it can lead to chronic infection.
Discuss complications that may arise from HEV infection during pregnancy.
🩺 Liver Failure: Pregnant women with HEV are at a higher risk of developing acute liver failure.
🩺 Fetal Loss or Death: The infection can lead to fetal loss or even maternal death.
🩺 Up to 30% of pregnant women who contract HEV in the third trimester may die from the infection.
Further notes:
The third trimester is the final stage of pregnancy, spanning from week 28 until birth.
What are primary tests in the diagnosis of HEV infection?
(1) HEV IgM Antibodies (ELISA) [a positive result indicates a recent or current HEV infection]
(2) HEV RNA (RT-PCR)
Prevention measures against HAV and HEV are similar except for two aspects …
💉 Since HEV can be zoonotic, avoiding the consumption of undercooked or raw meat, particularly pork and other animal products that may be contaminated can reduce its spread.
💉 HEV vaccine is only licensed in China, whereas licensed HAV vaccine is globally available.
The most appropriate specimen for detection of Hepatitis A antibodies is ____________.
(a) urine
(b) liver biopsy
(c) saliva
(d) serum
(e) stool
serum
Which of the following is the most appropriate specimen for detection of Hepatitis A by PCR?
(a) Stool
(b) Liver biopsy
(c) Blood
(d) CSF
(e) Urine
(a) Stool
Which of the following statements concerning Hepatitis A is incorrect?
(a) Diagnosis is usually by virus isolation in cell culture
(b) Commonly causes asymptomatic infection in children
(c) Vaccination is useful in prevention
(d) The initial site of viral replication is the intestine
(e) It is a member of the Picornaviridae family
(a) Diagnosis is usually by virus isolation in cell culture
