Define Acute Viral Hepatitis. Describe its clinical features, investigations, management and complications.

Definition

• Acute viral hepatitis is an acute inflammation of the liver caused by the hepatotropic viruses (A, B, C, D and E).
• It is a common cause of jaundice in children; hepatitis A and E are the usual causes in India.

The Hepatitis Viruses

Clinical Features (phases)

• Prodromal (pre-icteric) phase — fever, malaise, anorexia, nausea/vomiting, distaste for food (and cigarettes in adults), and right-upper-quadrant discomfort.
• Icteric phase — jaundice, dark urine and pale stools, with tender hepatomegaly; symptoms often improve as jaundice appears.
• Convalescent phase — gradual recovery over weeks.
• Many children (especially with hepatitis A) have an anicteric or subclinical illness.

Investigations

• Liver enzymes — markedly raised transaminases (ALT > ast); raised bilirubin (conjugated + unconjugated).
• Serology — IgM anti-HAV (acute A), HBsAg and IgM anti-HBc (acute B), anti-HCV/HCV-RNA, IgM anti-HEV.
• Prothrombin time / INR — the best marker of severity/prognosis (a prolonged PT warns of liver failure).
• Ultrasound to exclude obstruction if the picture is atypical.

Management

• Mostly supportive — rest, adequate nutrition and hydration; there is no need for a special 'liver diet' or forced fat restriction.
• Avoid hepatotoxic drugs (paracetamol in high doses, alcohol) and unnecessary medication.
• Monitor for fulminant hepatic failure — worsening jaundice, bleeding, altered sensorium (encephalopathy).
• Specific antiviral therapy for chronic hepatitis B or C (not for acute A/E).

Complications & Prevention

• Complications — fulminant hepatic failure (esp. E, B); chronic hepatitis, cirrhosis and hepatocellular carcinoma (B, C).
• Prevention — hepatitis A and B vaccines; safe water, sanitation and hand hygiene (A, E); safe blood/needles and birth-dose HBV + HBIG to prevent vertical B.

Pathogenesis

Most hepatocyte injury is immune-mediated (the host's cytotoxic T-cell response to virus-infected liver cells) rather than a direct cytopathic effect, causing hepatocyte necrosis, cholestasis and the rise in transaminases.

Incubation & Course

• Hepatitis A — incubation ~2–6 weeks; almost always self-limiting in children.
• Hepatitis E — ~2–9 weeks; self-limiting but severe in pregnancy.
• Hepatitis B — ~1–6 months; risk of chronicity (highest when acquired young).

Differential Diagnosis of Jaundice

• Pre-hepatic — haemolysis (unconjugated, normal enzymes).
• Hepatic — other causes: drug-induced, autoimmune hepatitis, Wilson disease, leptospirosis, enteric fever.
• Post-hepatic — obstruction (choledochal cyst, stones) — pale stools, high GGT/ALP.

Warning Signs of Fulminant Failure

• Deepening jaundice with altered behaviour/drowsiness (encephalopathy).
• Bleeding, a prolonging PT/INR, and a shrinking liver — refer urgently.

Prognosis

• Hepatitis A and E in children usually recover completely without sequelae.
• The main risks are fulminant failure (a small minority) and, with hepatitis B/C, progression to chronic liver disease, cirrhosis and hepatocellular carcinoma.

Supportive Care in Detail

• Rest as needed; maintain hydration and a normal balanced diet (no forced fat restriction).
• Antiemetics for troublesome vomiting; avoid sedatives and hepatotoxic drugs.
• Daily assessment for jaundice, bleeding and mental status in significant cases.

Post-exposure Prophylaxis & Public Health

• Hepatitis A — vaccine (± immunoglobulin) for susceptible close contacts; ensure safe water and hand hygiene.
• Hepatitis B — vaccine + HBIG after significant exposure; birth-dose vaccine for newborns of carrier mothers.
• Hepatitis A/E — enteric precautions; both are notifiable in outbreaks.