Hepatitis A

Hepatitis A is an acute infectious disease of the liver caused by the Hepatovirus A (HAV). This type of viral hepatitis is characterised by symptoms such as nausea, vomiting, diarrhoea, dark urine, jaundice, fever, and abdominal pain.

The disease has a usual onset of 2-6 weeks post-infection and typically lasts for about 8 weeks. Acute liver failure is a rare but severe complication, more common in the elderly.

Virology

Hepatitis A is caused by the Hepatovirus A, a non-enveloped virus containing a positive-sense, single-strand RNA. It belongs to the Picornaviridae family.

The virus spreads primarily through the faecal-oral route, often in areas with poor sanitation. It can survive in the environment for long periods and is resistant to detergents, acid, and high temperatures.

Signs and Symptoms

Symptoms of hepatitis A can mimic influenza and may include:

• Fatigue
• Fever
• Nausea
• Appetite loss
• Jaundice (yellowing of the skin and eyes)
• Dark urine
• Diarrhoea
• Light or clay-coloured faeces
• Abdominal discomfort

Most children infected with HAV are asymptomatic, whereas adults tend to exhibit more severe symptoms. Symptoms usually appear 2-6 weeks after infection and last less than 2 months, although some cases can persist for up to 6 months.

Diagnosis

Diagnosis of hepatitis A is confirmed through blood tests detecting HAV-specific IgM antibodies, which appear shortly after infection and remain for up to 14 weeks. Elevated levels of liver enzyme alanine transferase (ALT) in the blood are also indicative of liver damage.

Prevention

Preventive measures for hepatitis A include vaccination, good hygiene practices, and proper food handling. The hepatitis A vaccine is highly effective, providing immunity in over 95% of cases and lasting for more than 25 years.

It is recommended for children and high-risk adults, including those travelling to areas with high HAV prevalence.

Treatment

There is no specific treatment for hepatitis A. Management focuses on supportive care to maintain comfort and adequate nutrition.

This includes hydration and rest, with medications for nausea and diarrhoea as needed. Most people recover fully without long-term liver damage.

Prognosis

The prognosis for hepatitis A is generally good, with a low mortality rate. However, the risk of acute liver failure increases with age and underlying chronic liver disease.

Young children usually experience a milder form of the disease, while adults may have more severe symptoms.

Epidemiology

Globally, there are approximately 1.4 million symptomatic HAV infections annually, with a higher prevalence in regions with poor sanitation. The disease is common in developing countries, where most children are infected by age 10 and gain lifelong immunity.

In developed countries, hepatitis A often occurs in outbreaks among unvaccinated adults and travellers.

In summary, hepatitis A is a preventable disease with a generally favourable outcome, especially when good hygiene practices and vaccination are implemented. Understanding its transmission, symptoms, and preventive measures is very important for managing and controlling outbreaks.

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Self-assessment MCQs (single best answer)

What is the primary mode of transmission for Hepatitis A?

Which of the following symptoms is most commonly associated with Hepatitis A?

What type of virus causes Hepatitis A?

Which age group is most likely to have asymptomatic infections of Hepatitis A?

Which of the following is the most effective preventive measure against Hepatitis A?

How long does the initial dose of the Hepatitis A vaccine provide protection?

In which type of climate is Hepatitis A most prevalent?

What is the typical incubation period for Hepatitis A?

Which of the following lab findings is indicative of acute Hepatitis A infection?

Which of the following complications is most commonly associated with Hepatitis A in the elderly?