HAV infection is seen throughout the world and an estimated 1.5 million cases occur per year (1).
- prevalence of the disease is closely related to socio-economic condition
- it is endemic in majority of the low income countries (due to poor sanitation and food hygiene) where it’s often seen in children, who are likely to be asymptomatic
- in developed countries with temperate weather, incidence follow a cyclic pattern (2) although in UK there has been no peak in incidence since 1990 (3)
- improved standards of living and hygiene have led to a marked fall in the incidence of hepatitis A infection
- in 1996, the overall seroprevalence of hepatitis A in England and Wales was estimated to be 31%, and was 11% among those aged 10-19 years
- therefore, the majority of adolescents and adults remain susceptible to hepatitis A infection and will remain so throughout life, with the potential for outbreaks to occur
- a decrease in overall incidence of hepatitis A has been reported in the European Union (EU) (due to better living condition and reduced exposure to infection, especially in early childhood) (4)
Infections in adults are uncommon in endemic countries since most are immuned to the disease (due to exposure to the virus at a young age) (1).
Outbreaks may occur in developed countries whenever the virus is introduced due to lack of immunity (1).
- outbreaks among men who have sex with men (in UK) and among injecting drug users (in Scotland) have been reported (3)
- independent outbreaks occurred in Czech Republic, Latvia and Slovakia in 2008 with a significant proportion of patients being young adults (4)
Children of school age are most often affected. Adults are usually infected by spread from children.
The incidence of hepatitis A in England and Wales has decreased considerably during the past years from 1,337 in 1997 to 300 in 2014 (3):
- Travel abroad is a common risk factor for sporadic cases in the UK. The highest risk areas for UK travelers are the Indian subcontinent, Middle East, Africa and South East Asia, but the risk now extends to Eastern Europe.
- Outbreaks associated with food, particularly frozen berries, both within the UK and across Europe have increased in the last decade.
Epidemics may occur, usually associated with water or food contamination.
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