Hepatitis A Virus (HAV)

Hepatitis A (HAV)

Definition and Etiology

Hepatitis A virus is responsible for most forms of acute and benign hepatitis. It is a member of the picornavirus family and contains RNA. It is heat-stable and primarily infects humans and other primates.

Epidemiology and Transmission

• Prevalence: Global, especially in developing countries.
• Transmission: Person-to-person via the fecal-oral route.
• Incubation period: 15–50 days.
• Communicability: Highest 1 week before and after the onset of symptoms. Fecal viral excretion is prolonged in infants.

Risk Factors:

• Contact with infected persons.

• International travel to areas with poor hygiene.

• Childcare centers.

• Foodborne outbreaks.

• Perinatal transmission: Rare; pregnancy does not generally increase complications for the mother or newborn.

Clinical Manifestations of HAV

• Age correlation: Often asymptomatic or mild in children <5 years. Older adolescents and adults are more likely to be symptomatic.
• Symptoms: Often resemble viral gastroenteritis; can be anicteric.
• Duration: Typical illness lasts 7–14 days.

Diagnosis of HAV

• Acute Infection: Detected via anti-HAV IgM. Detectable at symptom onset and remains positive for 4–6 months.
• Past Infection/Immunity: Anti-HAV IgG is detected within 8 weeks and confers long-term protection.
• Viral PCR: Commercially available.
• LFTs: Elevated transaminases (ALT/AST), bilirubin, alkaline phosphatase, 5’-nucleotidase, and γ-glutamyl transpeptidase (non-specific).

Complications and Treatment

• Complications: Full recovery is typical. Fulminant hepatic failure (ALF) is rare (more common in adults/immunocompromised). Prolonged cholestatic syndrome may occur.
• Treatment: No specific treatment. Supportive care (fluid and nutritional management) is the cornerstone.
  • Pruritus: Antipruritic agents for cholestasis.
  • Vitamins: Fat-soluble vitamin supplementation if needed.
  • Avoid: Acetaminophen, as it can exacerbate liver damage.
  • Note: Corticosteroids offer no benefit.

Prevention and Prognosis

• Prognosis: Excellent, with no long-term sequelae and lifelong immunity. No risk of chronic infection.
• Vaccination: Universal vaccination recommended for all children. Booster dose ≥6 months after the initial dose. Preferred over Ig for pre/post-exposure in those ≥12 months.
• Immunoglobulin (Ig): Used for travelers <6 months or those allergic to vaccines.

General Infection Control:

• Handwashing: Essential after diaper changes and before handling food.
• School Exclusion: From 2 weeks before to ~7 days after jaundice onset.
• Hospital Precautions: Contact and standard precautions for 1 week after symptom onset.

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IM

HEPATITIS A

Key Features

1. Most common cause of acute viral hepatitis.
2. Causes only acute hepatitis. No carrier state or chronic hepatitis. Usually, does not happen twice.

Transmission

• Fecal-oral route: Contamination of food and water due to poor hygiene by food handlers.
• Saliva of the infected person also contains the virus but in very small amounts.

Clinical Features

Prodromal Phase (Initial 1-2 weeks)

• Anorexia (loss of appetite)
• Nausea
• Malaise (general feeling of discomfort)
• Bad taste in the mouth
• Fever
• Jaundice is absent initially

Icteric Phase (Next 3-6 weeks)

• Jaundice (yellowing of skin and eyes)
• Pain in the right upper quadrant of the abdomen
• Dark urine
• Pale stools
• Tender hepatomegaly (enlarged liver)

Severity of Hepatitis A

• Asymptomatic: Usually in children
• Mild to Moderate Symptoms: Most cases
• Fulminant Hepatic Failure: Rare but serious complication

Investigations

• Liver Function Tests (LFTs):
  • High bilirubin (mainly direct bilirubin)
  • AST & ALT are very high
  • Alkaline Phosphatase slightly high
• Urine: Contains bilirubin
• Diagnostic Test: Hepatitis A antibody (anti-HAV)

Treatment

• No specific drug treatment. The disease is self-limited and usually results in complete recovery within 3 months.
• Strict isolation of the patient is not advised, but they should wash their hands thoroughly after defecation.
• Good nutrition: Eat whatever can be tolerated.
• Vitamin supplements
• Avoid alcohol and hepatotoxic drugs
• Symptomatic treatment

Prevention

• General Measures:
  • Good hygiene
  • Drink bottled water in high-risk areas
  • Avoid risky foods
• Immunization: Hepatitis A vaccine is recommended for:
  • Patients with other chronic liver disease
  • Patients traveling to a high-risk area for a long time

Rapid Fire Questions (Hepatitis A)

• Mode of transmission of Hep A? fecal oral
• Which test is diagnostic? anti-HAV
• In hepatitis, which type of bilirubin is elevated predominantly? Direct
• Which specific drug is used for Hep A treatment? no specific drug
• Who should get the Hep A vaccine? High risk area for CHD
• How to avoid getting infected? avoid risk factors
• A man tells you that he had Hep A 2 years ago. Now he is jaundiced. The doctor tells him that he has Hep A re-infection. Is the doctor right? no, antibodies protective for life

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Thera

Transmission:

• Fecal-oral: contaminated water or food (raw shellfish).
• Anal oral sex.
• Parenteral (not common).

Pathogenesis:

• hepatocytes destruction by the immune system,
• (the virus is not cytopathic).

Clinical features:

• Right upper quadrant pain, tender hepatomegaly, fever, malaise, anorexia, nausea, vomiting, jaundice (dark urine and pale stools), pruritus.
• Mortality rate is 0.1–0.3%.

Diagnoses:

• Antigens detection in stool.
• RNA detection in stool & blood samples by rt-PCR.
• Anti-HAV IgM in serum.
• IgM - Currently infected
• IgG - infected before

Treatment

• Generally self-limited.
• Symptomatic treatment: antiemetics, rehydration.
• Use medications that are metabolized by the liver with caution (e.g., acetaminophen “paracetamol”).

Prevention:

• Inactivated vaccine.