[Epidemiology and surveillance of hepatitis E in Italy: data from the SEIEVA surveillance system 2007-2019]

Background: hepatitis E is a disease spread all over the world, with endemic levels varying according to ecological and socioeconomic factors. In developing countries, large epidemics spread mainly through contaminated water; in developed countries, hepatitis E has always been considered a sporadic disease, closely associated to the travels to endemic areas, especially in Southeastern Asia. In the last years, this perception is significantly changing, because of an increasing number of autochthonous cases reported in many European countries. Objectives: to describe the epidemiological picture of hepatitis E in Italy from 2007 to 2019. Design: descriptive study based on the cases reported to the special surveillance of acute viral hepatitis (SEIEVA); case-control analytical study for the analysis of risk factors associated with hepatitis E. Setting and participants: hepatitis E cases reported to SEIEVA in the period 2007-2019. Main outcome measures: number of cases notified by year, percentages of cases exposed to known risk factors, odds ratios. Results: from January 2007 to June 2019, 385 hepatitis E cases were notified to SEIEVA. The annual number increased from 12 in 2007 to 49 in 2018, the increasing trend continued in 2019, when 39 cases were observed in the first 6 months of the year. Northern and Central Regions reported most of the cases; only a few were diagnosed in Southern Regions. Based on SEIEVA data, the trend of hepatitis E notifications has increased according to the increasing propensity to the differentiated diagnosis, at least until 2018. However, only 46% of suspected cases are tested to detect the presence of anti-HEV IgM antibodies, during the observation period; the percentage of tested cases is significantly lower in the South than in Northern and Central Italy (p<0.001). The reported cases have a median age of 48 years (range: 5-87) and are mostly males (80%); 32% was observed in foreign citizens mainly from endemic areas of South Asia (Bangladesh, India, and Pakistan). In 72.5% of cases, the infection was contracted in Italy. The most frequent risk factor is the consumption of raw or undercooked pork meat, especially sausages (70% of cases), significantly associated with hepatitis E risk (OR 3.0; IC95% 1.4-6.1). Other important risk factors are wild boar sausages consumption (40% of cases, OR 4.6, not statistically significant), and travels to endemic areas during the six weeks before the disease (31% of cases, OR 3.2; IC95% 1.6-6.4). Conclusions: hepatitis E can now be considered as endemic even in industrialized countries. In Italy, from 2007 an increasing number of cases has been reported. However, the real impact of HEV infection is still underestimated due to the limited number of clinical centres which perform tests for the search of anti-HEV IgM antibodies in cases of acute hepatitis. An ad hoc surveillance has been activated in January 2019 in some Local Health Units/Regions and extended to a national level starting from January 2020. This initiative is necessary in order to better dimension the burden of the disease associated with HEV infection, to study its epidemiology, and to increase awareness of this infection among health professionals.