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Swine hepatitis E virus (HEV) infection is widespread in pig herds worldwide. Infected pigs excrete large quantities of virus in the faeces, and HEV RNA has been detected in retail pig liver in several countries. In addition to the liver, HEV RNA has been detected in extra-hepatic sites in the pig including stomach, small intestine, colon, spleen, kidney, lung and muscle. Although asymptomatic in pigs there is growing evidence for zoonotic transmission of HEV as a cause of autochthonous hepatitis E in developed countries.
The European FP7 project VITAL (Integrated Monitoring and Control of Foodborne Viruses in European Food Supply Chains) aims to gather data on virus contamination of food and environmental sources, for quantitative viral risk assessment. Fourteen European laboratories are investigating fruit, vegetable, shellfish and pork food supply chains for specified viral contamination. The VLA role was to investigate HEV contamination in the pork food chain in England.
Samples were tested for the presence of HEV (target virus) and Porcine Adenovirus (PAdV; indicator of faecal contamination). Three points in the food supply chain were sampled, collecting faeces and liver samples at the production stage (abattoir), muscle samples at site of processing (meat processing plant) and sausage samples from point of sale. In addition, surface swabs were collected from these premises, in areas where viral contamination was considered more likely.
HEV was detected at all three points of the pork food supply chain, and with the exception of point of sale, the prevalence of HEV relative to PAdV would be consistent with a potential faecal contamination source. Six of 63 (9.5%) sausages tested had detectable HEV RNA: all six positive samples identified were from one of three batches of sausages that had been collected. In terms of foodborne transmission of HEV these represent the most significant findings. Available data suggests that the consumption of raw / undercooked sausage is a potential route of HEV transmission. Crucially, it is not known if HEV that was detected in this study was viable and this will now be investigated using in vitro cell culture. Information on the viability of the virus will be critical in the assessment of the risk to public health of HEV contamination in the pork food supply chain.
S. Grierson, F. Martelli, A. Berto, M. Banks. Investigation of the prevalence of hepatitis e virus contamination through the pork food supply chain in England. 6th International Symposium on Emerging and Re-emerging Pig Diseases: 53