Hepatitis A Virus

Key points to remember

• Hepatitis A is a contagious liver infection caused by the Hepatitis A Virus (HAV).
• It mainly spreads through the fecal–oral route, often from contaminated food or water.
• Common symptoms include fever, nausea, vomiting, fatigue, loss of appetite, jaundice (yellowing of the skin and eyes), dark urine, and pale stools. However, many young children may HAVe mild or no symptoms.
• The virus affects liver cells, and the body’s immune response, not the virus itself, causes most of the liver inflammation.
• HAV infection is self-limiting, and people who recover develop lifelong immunity.

Keywords

Hepatitis A Virus, HAV, RNA virus, Fecal–oral transmission, Picornaviridae, Jaundice, Vaccine-preventable disease, Endemic areas.

Definition and Structure

The Hepatitis A Virus (HAV) is a non-enveloped, icosahedral virus with a positive-sense, single-stranded RNA genome of about 7.5 kb.
It belongs to the Picornaviridae family. Unlike other hepatitis viruses, HAV lacks a lipid envelope, which makes it resistant to environmental stress, such as acid and heat.

Replication

HAV replicates in the cytoplasm of liver cells (hepatocytes). It uses an internal ribosome entry site (IRES) to translate its RNA and form viral proteins.
The virus is then released without destroying the host cell and is excreted in feces, allowing it to spread easily in unsanitary conditions.

Epidemiology

Hepatitis A is common in areas with poor sanitation and limited access to clean water.
According to the World Health Organization (WHO), thousands of deaths occur annually due to severe cases of HAV, although most recover completely.
Regions with high endemicity include sub-Saharan Africa, South Asia, and parts of Latin America.
In developed countries, HAV outbreaks occur mainly among travelers, men who HAVe sex with men (MSM), and due to food contamination.

Transmission

• Fecal–oral route: The main way HAV spreads, especially through contaminated food, water, or close personal contact.
• Person-to-person transmission: Common in households and childcare centers.
• Foodborne outbreaks: Linked to raw or undercooked seafood and unwashed produce.
  Good hygiene and sanitation significantly reduce transmission.

Pathogenesis

After ingestion, HAV travels to the liver, where it infects hepatocytes.
The virus itself causes minimal direct cell damage. Instead, the body’s immune system, particularly T-cells, attacks infected cells, leading to inflammation and liver injury.
This immune response clears the infection but can cause temporary liver dysfunction.

Immunity and Chronicity

• Lifelong immunity develops after recovery due to the presence of anti-HAV IgG antibodies.
• No chronic infection: HAV does not cause long-term liver disease or chronic hepatitis.
• Reinfection is rare, and relapsing cases resolve completely.

Clinical Features

The incubation period is about 15–50 days.
Children under 6 years usually have mild or no symptoms.
Older children and adults often experience:

• Fever and fatigue
• Nausea, vomiting, and abdominal pain
• Jaundice (yellowing of the eyes and skin)
• Dark urine and pale stools

Most patients recover within 2 months, though fatigue can last longer. Severe or fulminant hepatitis is very rare but may occur in older adults or those with pre-existing liver disease.

Diagnosis

Hepatitis A is diagnosed through blood tests:

• Anti-HAV IgM antibodies confirm acute infection.
• Anti-HAV IgG antibodies indicate past infection or immunity.
  Liver function tests often show elevated ALT and AST enzymes due to liver inflammation.

Treatment

There is no specific antiviral treatment for Hepatitis A.
Most cases require only supportive care, including:

• Adequate rest
• Hydration
• Nutritious food
• Avoiding alcohol and liver-toxic medications
  Hospitalization is necessary only in rare severe cases.

Prevention

Vaccination is the most effective way to prevent Hepatitis A.

• Inactivated HAV vaccines provide long-term protection.
• Recommended for children, travelers, healthcare workers, and high-risk groups.
  Post-exposure prevention:
• Vaccine or immunoglobulin given within 2 weeks after exposure can prevent infection.
  Hygiene tips:
• Wash hands before eating and after using the toilet.
• Drink safe, clean water.
• Avoid raw or undercooked foods in endemic areas.

Conclusion

Hepatitis A is a preventable and self-limiting liver disease caused by the Hepatitis A Virus. Good sanitation, vaccination, and public health awareness can nearly eliminate its spread. Early diagnosis and proper hygiene practices ensure complete recovery and protection from future infection.