Hepatatis A Vurus

Question 1

Classification

Answer 1

Family: Picornaviridae

Genus: hepatovirus

Species: hepatitis A

(Hint: occurs in the day time, without clothes)

Question 2

Characteristics

Answer 2

- Naked nucleocapsid virus 
>>> +ssRNA
- No viron polymerase 
- one serotype
- Acid stable —> reaches the gut

Question 3

Transmission

Answer 3

Fecal-oral route:

> Contaminated water (common in developing countries) 
To purify water: 
- chlorination 
- bleaching
- UV radiation 
- boiling 

> shell-fish contamination —> typical in developed countries

In contrast to HBV and HCV, blood-borne transmission of HAV is uncommon because viremia is brief and of low titer

Question 4

Pathogenesis

Answer 4

• The virus replicates in the GI tract then spreads to the liver during a brief veremic period
• the virus is not cytopathic for the hepatocyte
  > Hepatocellular injury is caused by immune attack by cytotoxic T cells

Question 5

Disease

Answer 5

Hepatitis A

Signs and symptoms:
- fever
- vomiting 
- jaundice —> only seen in adults 
  > in children —> anicteric hepatitis
Smokers develop aversion to smoking

Lasts for 1 month
Often self-limiting
No chronic or carrier state

Question 6

Microbiological diagnosis

Answer 6

• Isolation of the virus from clinical specimens is not done
• The most useful test to diagnose acute infection is IgM antibody

Question 7

Treatment and prevention

Answer 7

Treatment:
No antiviral drug is available

Prevention:

Vaccine —> killed vaccine

Administration of immune globulin during the incubation period can mitigate the disease