Hepatitis A virus - MegaMicro

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Hepatitis A virus

Micro > Virology > RNA viruses > Single Stranded RNA viruses > Picornavirus
Overview:
Hepatitis A Virus is a naked, positive-sense single-stranded RNA virus with an icosahedral capsule. It is classified as a picornavirus.
Transmission:
HAV is spread primarily by a fecal-oral route. It can survive outside the body for months and is highly stable, resistant to detergents, acid, and high temperatures. Outbreaks generally occur from a single source as there is a long asymptomatic period of high viral shedding. It is more common in conditions of overcrowding or poor hygiene. Additional persons-at-risk include travelers to endemic regions, intravenous drug users, and MSM populations.
Pathogenesis:
After being acquired via ingestion, HAV penetrates through the lining of the gastrointestinal tract to reach the blood, which carries it to the liver. It binds and enters hepatocytes and Kupffer cells via the HAC cell receptor 1 glycoprotein. After replicating, it is released from the cells via exocytosis (it does not lyse infected cells). There is no chronic infection of HAV.

Prior infection with Hepatitis A confers protection against reinfection

Clinical manifestations:
Symptoms are caused via immune-mediated damage to the liver. Initial symptoms include fever, fatigue, nausea, loss of appetite, vomiting and abdominal pain. Dark urine, pale stool and jaundice may follow. While jaundice is observed in 70% to 80% of adults, it is observed in only 10% of cases involving children.

Generally is self-limited course. Hepatitis A does not lead to chronic infection

Diagnosis:
Diagnosis can be made based on a specific serological test, and may be supplemented by clinical symptoms, identification of the known infection source. Serology is done via enzyme-linked immunosorbent assay (ELISA) directed towards anti-HAV IgM.

Treatment:
Generally supportive.

Prophylaxis consisting of immune serum globulin may be given up to 2 weeks after the exposure in order to prevent the clinical illness. Cell-mediated immunity (NK cells and cytotoxic T-cells) are needed to clear the infection by eliminating infect liver cells.
Post-exposure prophylaxis can be attained by administering serum immune globulin, or (preferably) vaccine.
Vaccine:
A vaccine of killed HAV is recommended for all children as well as adults who are at high risk for infection. It is administered in two doses, 6 months apart, generally concurrently with the HBV vaccine.
Related concepts
1. Hepatitis
2. Fecal-oral
3. Picornavirus
4. Liver
5. jaundice

 
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