Public health risks associated with hepatitis E virus (HEV) as a food-borne pathogen

Abstract

Hepatitis E virus (HEV) is an important infection in humans in EU/EEA countries, and over the last 10 years more than 21,000 acute clinical cases with 28 fatalities have been notified with an overall 10-fold increase in reported HEV cases; the majority (80%) of cases were reported from France, Germany and the UK. However, as infection in humans is not notifiable in all Member States, and surveillance differs between countries, the number of reported cases is not comparable and the true number of cases would probably be higher. Food-borne transmission of HEV appears to be a major route in Europe; pigs and wild boars are the main source of HEV. Outbreaks and sporadic cases have been identified in immune-competent persons as well as in recognised risk groups such as those with pre-existing liver damage, immunosuppressive illness or receiving immunosuppressive treatments. The opinion reviews current methods for the detection, identification, characterisation and tracing of HEV in food-producing animals and foods, reviews literature on HEV reservoirs and food-borne pathways, examines information on the epidemiology of HEV and its occurrence and persistence in foods, and investigates possible control measures along the food chain. Presently, the only efficient control option for HEV infection from consumption of meat, liver and products derived from animal reservoirs is sufficient heat treatment. The development of validated quantitative and qualitative detection methods, including infectivity assays and consensus molecular typing protocols, is required for the development of quantitative microbial risk assessments and efficient control measures. More research on the epidemiology and control of HEV in pig herds is required in order to minimise the proportion of pigs that remain viraemic or carry high levels of virus in intestinal contents at the time of slaughter. Consumption of raw pig, wild boar and deer meat products should be avoided.

Keywords: HEV; food‐borne; hepatitis E virus; liver; pork; wild boar.

Figure 1

Phylogenetic tree of representative members of the Hepeviridae family, which is divided into two genera: Orthohepevirus and Piscihepevirus

1. The name of different Orthohepevirus species (A–D) is added at the junction of the last common ancestor for each species. Genotypes of non‐zoonotic HEV species (red), genotypes including HEV strains originating from animals and humans (blue), genotypes infecting humans only (green), and genotypes infecting wild boar that are not linked to human infections (striped blue). Copyright ©2016 by the authors; licensee MDPI, Basel, Switzerland (Doceul et al., 2016).

Figure 2

Distribution of sequences available in the GenBank (April 2016) database along the HEV genome (Courtesy of H. Vennema, RIVM)

Figure 3

Number of reported human HE cases by year from 22 EU/EEA countries, 2005–2015 (ECDC, 2017)

1. *Data available for Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic, Estonia, Finland, France, Germany, Hungary, Italy, Latvia, the Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden and the UK.

Figure 4

Number of human HE cases by origin of infection, 15 EU/EEA countries, 2005–2015 (ECDC, 2017)

Figure 5

Inactivation curve for HEV, based on data from Emerson et al. (2005). These experiments showed, for HEV‐1 strain, that the initial infectivity decay is large, but is minimal during the second phase (Bouwknegt et al., 2013)