Hepatitis A virus

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What is Hepatitis A virus?

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Hepatitis A is a picornavirus - meaning that it is made up of single-stranded RNA. Although many viruses can affect the liver and cause a 'hepatitis' picture, the Hepatitis A virus has its name because it is one of six viruses that specifically target the liver.

Who gets Hepatitis A virus?

Hepatitis A is the most common type of viral hepatitis occurring world-wide. Hepatitis A is most prevalent in the Autumn. Hepatitis A most commonly affects children and young adults.

Predisposing Factors

Hepatitis A is spread by the fecal-oral route - hence it is usually transmitted by the consumption of contaminated water, shellfish, or other food.

Hepatitis A virus can spread throughout a community because of poor hygiene and over-crowding.

HAV outbreaks usually originate from a common source - water supply, restaurant, day-care center.

Raw or improperly treated sewerage can taint the water supply and contaminate shellfish. Shellfish (e.g. mussels, clams, oysters) are filter-feeders and hence can concentrate the Hepatitis A virus (HAV).

Progression

Hepatitis A is ingested and enters the bloodstream through the epithelial lining of the intestines to reach the liver. The virus replicates in liver cells and is released into the bile, and then into the stool for about 2 weeks before the onset of clinical illness and up to 1 week after. The disease is most infective just before the onset of jaundice. Clinically the disease has an incubation period of 2-3 weeks. Symptoms are non-specific, but may include nausea, anorexia and a distate for cigarettes. Some patients recover at this stage and remain anicteric (without jaundice). Those that do not, become jaundiced 1-2 weeks later. As the jaundice deepens, their urine darkens and stools pale. In some cases there may be tender lymphadenopathy (enlargement of the lymph nodes) and a transient rash. Then the jaundice usually lessens and the majority of illnesses end in 3-6 weeks. Rarely the disease may be very severe with fulminant (rapid severity) hepatitis, liver coma and death.

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