hep A (hepatitis A virus)

Last edited 02/2020

Hepatitis A virus hepatitis accounts for 20-25% of clinical hepatitis worldwide. It is due to a small, single stranded RNA picornavirus (1). HAV hepatitis may be referred to as infectious hepatitis.

• usually self limiting
• fulminant hepatitis can occur rarely (<1%) (1)
• does not lead to chronic hepatitis (2)
• the virus is resistant to freezing, detergents and acids but inactivated in temperatures higher than 185°F (85°C) or by formalin and chlorine (3)

HAV infections acquired in the UK usually presents as:

•  sporadic cases
•  community-wide outbreaks - results from person to person transmission  
•  point of source outbreaks - uncommon, related to contaminated food (2)

The risk of acquiring HAV infection is higher in:

• travellers to developing countries
• men who have sex with men
• users of illicit drugs
• those with clotting factor disorders
• persons who handle nonhuman primates (5)

Infection with HAV induces lifelong immunity (1).

Summary:

Reservoir:

• Human gastrointestinal tract

Epidemiology:

• Hepatitis A is no longer endemic in the UK and cases represent either importation following acquisition abroad or the importation of contaminated food. Frozen food or food components have been associated with outbreaks in mainland Europe, Ireland and the USA
• clusters, often in families or social groups, commonly occur around the primary case but onward transmission is otherwise uncommon

Transmission:

• Faeco-oral route
• transmission can also occur during sexual contact, particularly amongst MSM and through injecting drug use
• transmission within households is very common. Children <6 years are particularly effective transmitters, especially in schools

Incubation period:

• average = 28 days (Range 15-50)

Infectivity:

• two weeks before the onset of symptoms to one week after the onset of jaundice. Where jaundice is not reported, a history of dark urine or pale stools should be enquired about. If there are no symptoms of jaundice, onset of other symptoms (such as fatigue, nausea, and fever) should be used
• shedding may continue for many weeks but does not appear to be associated with transmission of infection
• a chronic carrier state is not known to follow acute infection

Reference:

• (1) Health Protection Agency (HPA) 2009. Guidance for the prevention and control of hepatitis A infection
• (2) Department of Health (DH) 2019. Immunisation against infectious disease - "The Green Book". Chapter 17 - hepatitis A  
• (3) Brundage SC, Fitzpatrick AN. Hepatitis A. Am Fam Physician. 2006;73(12):2162-8
• (4) Campos-Outcalt D. Hepatitis A: matching preventive resources to needs. J Fam Pract. 2004;53(4):292-5
• (5) PHE (2019). Recommendations for the Public Health Management of Gastrointestinal Infections