hepatitis A

Viral infection with the hepatitis A has a low prevalence in Europe; however, a retrospective analysis found that while overall hepatitis A prevalence is decreasing, some regions still have a moderate to high risk of hepatitis A infection.

Hepatitis A is a disease caused by a viral infection of the liver by the hepatitis A virus. Many cases are asymptomatic; however, some individuals experience extreme nausea, vomiting, diarrhea, jaundice, and fever. Hepatitis A infection is also a risk factor for acute liver failure, which can cause death.

Hepatitis A is transmitted primarily through the fecal-oral route through person-to-person contact or consumption of contaminated food or water. The virus can also spread via sexual transmission or parenteral transmission by infected syringes or blood. Transmission has been reduced greatly by the development of a vaccine against the virus as well as improving sanitation and promoting proper hygiene in the food preparation industry.

Geographical areas can be characterised by high, intermediate, low, or very low levels of transmission of viral infections. The European Union (EU) and the European Economic Area (EEA) are two regions classified as having low and very low levels of hepatitis A prevalence, respectively. A vaccine against hepatitis A has been available in Europe since 1991, only reaching the USA in 1996. The World Health Organization (WHO) recommends universal vaccination for countries with intermediate levels of hepatitis A prevalence, and vaccination only in target risk groups in areas with low prevalence. However, the EU and EEA have a hepatitis A vaccination program of no-cost for all children regardless of this low rate of prevalence.

Despite the EU and EEA having a low viral prevalence, large differences between member states have been reported. A new systematic review published in The Lancet Infection retrospectively assessed prevalence and susceptibility in individuals in EU and EEA countries. To do so, they searched databases and public health institute websites for seroprevalence records published between 1975 to 2014. They defined seroprevalence (the level of virus in the blood) profiles as the proportion of the population with anti-hepatitis A antibodies at 15 and 30 years of age. They also assessed susceptibility profiles as the proportion of susceptible individuals at age 30 and 50.

Overall, this study showed a decreasing trend of seropositivity, or individuals with hepatitis A infection, over the past four decades. These decreases are likely due to the global use of the hepatitis A vaccine, improvements in hygiene, implementation of food-safety measures, and improved socio-economic conditions over time. However, they found that susceptibility to hepatitis A ranged between low and very high in adults and had a defined geographical gradient. Therefore, regional variability exists in the prevalence in Europe. This analysis is important for predicting future transmission rates and identifying preventative measures aimed at eradicating this virus.

Written by Neeti Vashi, BSc

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