Hepatitis A

Hepatitis A virus (HAV) is a picornavirus and an RNA virus. It usually causes mild, self-limiting acute hepatitis. There is no specific treatment.

Etiology

Like hepatitis E, transmission is faecal-oral. Transmission usually occurs due to:

• Contaminated food or water
• Close personal contact
• IV drug users
• Blood exposure (rare)

For hepatitis, bowels are vowels. Those hepatitides who are vowels have faecal-oral transmission.

Clinical features

HAV causes mild and self-limiting acute hepatitis. It is usually asymptomatic in children, and generally mild if symptomatic in any age. The incubation period is approximately 30 days.

Symptoms include non-specific symptoms and jaundice. Around 30% of adults experience jaundice symptomatic, while < 5% of children do, although non-specific symptoms are more frequent.

Progression to acute liver failure is very rare and occurs mostly in those with underlying liver disease. HAV cannot cause chronic hepatitis, but cholestatic hepatitis or relapsing hepatitis can occur.

Diagnosis and evaluation

Typical laboratory features of viral hepatitis can be present in hepatitis A as well as the other viral hepatitides:

• ESR low
• WBC low
• Lymphocytosis
• AST and ALT > 8x the normal value
• Mixed hyperbilirubinaemia
• ALP normal

Diagnosis is based on serology. IgM anti-HAV shows acute infection while IgG anti-HAV shows immunity to HAV, either due to past infection or vaccination.

Treatment

There is no specific treatment for HAV.

Prevention

HAV can be prevented by vaccine. The vaccine is not part of the childhood vaccination programme, but is recommended for:

• Travelers to intermediate and high HAV prevalence areas (tropics and subtropics)
• Men having sex with men
• IV drug users
• Persons with chronic liver disease

The vaccine is also indicated as post-exposure prophylaxis if within 14 days of the exposure. If the exposed person is immunodeficient, anti-HAV immunoglobulin (passive immunization) should be given as well.

Proper food and water safety as well as hygiene is also important for prevention.