Assessment of the risk of foodborne transmission and burden of hepatitis E in Switzerland

The objective of this study was i) to quantify the risk of hepatitis E for Swiss consumers by specified pork products and ii) to estimate the total burden of human food-borne hepatitis E in Switzerland. A quantitative risk assessment from slaughter to consumption was carried out according to the Codex Alimentarius framework. In the hazard characterization, assumptions were made due to the lack of a dose-response relationship for oral exposure to hepatitis E virus (HEV). The prevalence of HEV in 160 pig livers of 40 different Swiss fattening farms was examined and determined to be 1.3% (CI 0.3%; 4.4%). This result was used as input in the risk assessment model, together with data from other published studies. The annual burden of hepatitis E was estimated in terms of Disability Adjusted Life Years (DALY), using data about hepatitis E cases diagnosed between 2010 and 2015 at two major hospitals located in the canton Ticino. Only the risk of foodborne hepatitis E from products containing pork liver was evaluated, as those containing only pork meat could not be evaluated because of lack of data on HEV load in pork. Assuming that successful oral infection occurs in 1% of servings contaminated with high HEV loads (>105 genome copies), and that acute illness develops in 5% of susceptible consumers, the most likely annual number of foodborne hepatitis E cases in Switzerland was estimated to be 1481 (95% CI 552; 4488) if all products containing pork liver were considered. If only high-risk products, such as plain pork liver and liver sausages (e.g. Saucisse au Foie), were considered, the annual number of cases was estimated to be 176 (95% CI 64; 498). We were unable to calculate the total burden of hepatitis E in Switzerland due to lack of data. Yet, for the canton Ticino, it was shown that a significant increase had occurred from <5 DALY per 100,000 inhabitants before 2012 to >50 DALY per 100,000 inhabitants in 2015. This change could partly be due to an increased reporting and higher awareness among medical practitioners. Extrapolation to other regions could be accomplished if detailed information on food consumption patterns were available. Notification of HEV cases and attempts of cases source attribution would improve the basis for risk assessments.