Updated: February 11, 2007

Hepatitis A Virus (HAV)

HAV causes 'infectious/epidemic hepatitis'. This disease has been known for centuries and is spread by the faecal-oral route - outbreaks are frequently associated with consumption of shellfish.

HAV is a common cause of acute viral hepatitis, although the incidence has fallen since the introduction of a vaccine in the 1990s:

Graph

Clinically, HAV infection is very variable. >90% childhood infections are asymptomatic, but only 25-50% adult infections (as usual, the older you get, the worse it is). Incubation period from 10-50 days, fever, jaundice are main symptoms. 99% cases recover completely, a few cases experience permanent liver damage, fatalities ~0.1%.

The virus was first isolated by Purcell in 1973. In vitro, grows in a variety of cell lines, but rather poorly. HAV is a Picornavirus, formerly classified in the genus Enterovirus. Genome studies (sequence homology) showed that it did not belong in this genus and it has been reclassified in a genus of its own: Hepatovirus

Family (Subfamily)	Genus	Type Species
Picornaviridae	Enterovirus	Poliovirus
	Rhinovirus	Human rhinovirus A
	Hepatovirus	Hepatitis A virus
	Cardiovirus	Encephalomyocarditis virus
	Aphtovirus	Foot-and-mouth disease virus O
	Parechovirus	Human parechovirus
	Erbovirus	Equine rhinitis B virus
	Kobuvirus	Aichi virus
	Teschovirus	Porcine teschovirus

Both inactivated and attenuated vaccines are available, the inactivated form being more widely used. The availability of assays for and vaccines against HAV means that the incidence is likely to decrease in future. A combined hepatitis A and B vaccine (Twinrix^® - GlaxoSmithKline Biologicals) is now licenced for use in persons aged 18 years. This consists of the antigenic components used in Havrix (HAV) and Engerix-B (HBV) vaccines.

Prevalence

UK Department of Health current vaccination guidelines

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