Porcine Blood and Liver as Sporadic Sources of Hepatitis E Virus (HEV) in the Production Chain of Offal-Derived Foodstuffs in Poland

Abstract

Pig’s blood and liver are valuable edible slaughter by-products which are also the major ingredients of offal-derived foodstuffs. The aim of the study was an evaluation of the occurrence of hepatitis E virus (HEV) and porcine adenovirus (pAdV) as an index virus of faecal contamination in pig’s blood and liver for human consumption. In total, 246 samples of retail liver (n = 100) and pooled pig’s blood (n = 146) were analysed for the presence of HEV and pAdV. Blood samples were individually collected from 1432 pigs at slaughter age. Viral genomic material, including RNA of a sample process control virus was isolated from food samples using a QIAamp® Viral RNA Mini Kit. Virus-specific IAC-controlled real-time PCR methods were used for detection of target viruses. HEV RNA was found in 6 (2.4%; 95% CI: 0.9–5.2) out of 246 samples of tested foodstuffs. The virus was detected in pig’s blood (3.4%; 95% CI: 1.1–7.8) and liver (1.0%; 95% CI: 0.0–5.0) with no significant differences observed in the frequency of its occurrence between the two by-products (t = 1.33; p = 0.182 > 0.05); however PAdV was detected more frequently in pig’s blood than in liver (t = 4.65; p = 0.000 < 0.05). The HEV strains belonged to the 3f and 3e subtype groups and the pAdV strains were assigned to serotype 5. PAdV was detected in pigs regardless of the farm size from which they originated. The number of animals raised on the farm (the farm size) had no influence on the occurrence of HEV or pAdV infections in pigs (F = 0.81, p = 0.447 > 0.05 for HEV; F = 0.42, p = 0.655 > 0.05 for pAdV). Although HEV was detected in pig’s offal only sporadically, consumers cannot treat its occurrence with disregard as it demonstrates that HEV-contaminated pig tissues can enter the food chain.

Molecular Characterization and Phylogenetic Analysis of Hepatitis E Virus (HEV) Strains from Pigs Farmed in Eight European Countries between 2020 and 2022

“…Further studies, including full genome sequencing of unassigned strains needed for subtype attribution, will shed more light on HEV occurrence and subtype circulation in Austrian and Bulgarian pigs. A similar degree of variability was observed in Poland, where results of subtyping in pigs were reported for the first time and coincided with 3f and 3e subtypes detected in the production chain of offal-derived pork foodstuffs [64] and in the sole study on human Polish blood donors [65]. In contrary to this finding, Polish population of wild boars seems to have slightly different pool of infecting subtypes with respect to those detected in pigs [66], except for the 3i strains, which were also found in pigs in this study.…”

Detection of Hepatitis E Virus Infections in Wild Boars in Southwest Germany Using a Stepwise Laboratory Diagnostic Approach

“…Results corroborating seroconversion in artificially or naturally HEV infected pigs have been presented by several researchers, without statements on statistical calculations, however [49][50][51]. Furthermore, comparative studies on the detection of HEV RNA in the liver, which represents the target organ for HEV, and in serum positively screened wild boars showed almost identical results [18,52]. This makes serum a reliable sample matrix for the detection of HEV in infected wild boars based on antibody pre-testing.…”

Prioritization of pig farm biosecurity for control of Salmonella and hepatitis E virus infections: results of a European expert opinion elicitation

“…in both settings . This was another area with scarce evidence from published studies, with some studies showing no effect or alternative effects [ 10 ] and although studies suggest that the strict observance of safety rules by farm workers and visitors could reduce transmission of pig viruses such as HEV, direct evidence is lacking [ 44 ]. Lastly, using hygiene locks and changing rooms for indoor farms was ranked high for both pathogens.…”