Bacon and other cured pork meats have been identified as risk factors for hepatitis E virus (HEV) in England by researchers.

They found consuming bacon, cured pork meats, and pigs’ liver were significantly associated with HEV infection, confirming previous links to processed pork products.

Scientists investigated risk factors for HEV infections in the blood donor population in England via a case-control study from April 2018 to March 2019. Study participants were 117 HEV RNA-positive blood donors and 564 HEV RNA-negative donors.

Collected information from cases and controls included travel history, animal and environmental exposures, alcohol intake, medication, and other conditions. They were also asked about the food they ate and purchasing preferences with detailed questions about the consumption of pork products.

The most commonly reported symptoms were fatigue, joint pain, and headaches. Overall, 76 of 117 cases and 552 of 564 controls were asymptomatic. There was a greater presence of HEV in male than female blood donors but the reason for this is uncertain, according to the study published in Emerging Infectious Diseases.

link to pork from outside UK
The incubation period of HEV can be two to nine weeks. Patients were asked about the 9-week period before the date of their HEV RNA positive blood donation and controls about the 9-weeks before their donation.

Of 19 food items included, 14 were significantly associated with HEV infection and most were animal products. No patients and four controls were vegetarians. The final model showed the only variables of note were bacon, cured pork meats such as sliced salami and cabanos, and pigs’ liver. It is not yet clear whether curing is sufficient to inactivate HEV.

“The identification of these pork products highlights the importance of accurate information about cooking requirements as well as the role and importance of animal husbandry to prevent HEV infection in pigs. Targeting HEV infection at the source would prevent foodborne transmission to the population,” said researchers.

Hepatitis E virus has eight types; genotype 3 (G3) and G4 are primarily foodborne. The increase of HEV in England in 2010 coincided with the emergence of a novel HEV phylotype. No evidence has been found of this phylotype in pigs in England. Viruses detected in human clinical samples in the UK have been closely related to those found in pigs in Europe. Scientists said evidence suggests the risk comes from pork products from outside the UK.

Researchers said preventing the consumption of pigs’ liver would only lead to a modest reduction in HEV cases because few people eat it. They also didn’t find a risk associated with having pork pies or ham and sausages from a certain UK supermarket chain. This could be because of changes in the supplier or source of pork for the supermarket since a 2013 study made this link or differences between the study populations.

FSA asks Campden BRI to look at HEV
An increasing trend of acute HEV was seen in the United Kingdom from 2010 to 2016; with 1,212 cases reported in 2015, 1,243 in 2016, 1,002 in 2018, and 1,202 in 2019. HEV is the most common cause of diagnosed acute viral hepatitis in England and the annual estimate of infections is 100,000 to 150,000.

Methods for sampling and testing pork and other food products are not robust enough to provide information about contamination with infectious viruses, according to the study.

The Food Standards Agency (FSA) has commissioned Campden BRI and Glasgow University to assess the best way to detect hepatitis E virus in pork meat and pork products by optimizing elements of existing HEV extraction and detection methods.

There are evidence gaps on HEV and standardized and reliable detection methods are needed to get a better understanding. The developed method would be able to quantify HEV from pork meat, offal and pork products with low-level detection if possible. The final report will be published after the project ends in December 2022.

It is planned the developed system will be put forward as a candidate for International Organization for Standardization (ISO) certification as a standard method.