Farm biosecurity measures to prevent hepatitis E virus infection in finishing pigs on endemically infected pig farms

Predicting and preventing the next viral disease transmitted through food

The ability of viruses to infect humans following oral exposure and disrupt normal physiological or anatomical functions is a hallmark of their potential to cause foodborne disease. While the etiology of the vast majority of foodborne diseases remains undetermined, viruses are often identified as the culprit when the cause is ascertained. Many undiagnosed causes of foodborne illnesses, especially sporadic cases, may go undetected or be caused by yet-to-be-identified viruses. The potential for food to become a transmission vehicle for viral diseases that are not typically acquired following ingestion may be described within the epidemiological paradigm. This model considers the characteristics and interactions of the host (the human), the agent (the virus), and the environment (the food, the food producing animal or the food production environment). Importantly, these factors are not static and evolution of viruses, transformations in agrifood systems, and changes in environmental conditions and human health and behaviour may contribute to increased pathogenicity, virulence, or exposure. In the context of determining the potential for additional viruses to emerge as important causes of foodborne disease, factors that contribute to hazard characterization (e.g., receptor affinity and distribution) and exposure assessment (e.g., prevalence in food animals and food hygiene) are reviewed. Although it is not possible to predict the type, the timing nor the location of the emergence of the next important cause of foodborne viral disease, the deployment and implementation of actions and behaviours related to personal and food hygiene, sanitation, and safe food handling practices can reduce the likelihood and impact of known and emergent viruses on the safety of the food supply and human health.

A farm-to-consumption quantitative microbiological risk assessment for hepatitis E in pigs

Foodborne transmission appears to be a significant route for human hepatitis E virus (HEV) infection in Europe. We have developed a quantitative microbiological risk assessment (QMRA) for HEV infection due to consumption of three selected pork products (liver pâté, minced meat, and sliced liver), which models the steps from farm to human consumption in high detail, including within-farm transmission dynamics and microbiological processes such as cross contamination and thermal inactivation. Our model is unique in that it considers prevalence and viral load of two microbiological variables, HEV RNA and infectious HEV, expressing the latter in terms of the former through so-called "adjustment factors" where data are lacking. When the QMRA was parameterized for France and using infectious HEV, we found that sliced liver posed by far the highest risk of infection, with mean probability per portion3.35 × 10 - 4 [ 95 % CI ( 3.28 - 3.42 ) × 10 - 4 ] $3.35\times 10^{-4}\,[95\%\ \text{CI}\ (3.28-3.42)\times 10^{-4}]$ , corresponding to3447 ( 95 % CI 3372 - 3522 ) $3447\,(95\%\ \text{CI}\ 3372-3522)$ human cases annually. For minced meat, the probability of infection was3.68 × 10 - 8 [ 95 % CI ( 3.56 - 3.80 ) × 10 - 8 ] $3.68\times 10^{-8}\,[95\%\ \text{CI}\ (3.56-3.80)\times 10^{-8}]$ , with only21 ( 95 % CI 20 - 21 ) $21\,(95\%\ \text{CI}\ 20-21)$ human cases. While our model predicted appreciable levels of HEV RNA remaining in liver pâté at the point of consumption, the amount of infectious HEV and hence risk of infection was zero, emphasizing the importance of using the correct microbiological variable when assessing the risk to consumers. Owing to its highly mechanistic nature, our QMRA can be used in future work to assess the impact of control measures along the pork-supply chain at high resolution.

Environmental Surveillance of Hepatitis E Virus and Rat Hepatitis E Virus in Portugal and Spain, 2020-2022

Hepatitis E virus (Paslahepevirus balayani [HEV]) is an important cause of acute viral hepatitis globally, with zoonotic genotypes linked to transmission through consumption of raw or undercooked swine meat or products. Recently, Rocahepevirus ratti (RHEV), member of Hepeviridae family, has emerged as a potential public health concern, with some human cases being reported. The present study aimed to investigate the presence of HEV, as well as RHEV in wastewaters from northern Portugal and Spain (nPS). Given the reported decline in HEV detection in swine from several regions of the world, we also aimed to explore HEV and RHEV in fattened swine fecal samples from the same region of the wastewaters. Between April 2020 and January 2022, a total of 44 wastewater samples were collected from wastewater treatment plants in nPS, alongside 400 fattened swine fecal samples from five farms of the same regions. Wastewater and swine fecal samples RNA extracts were screened for HEV using pangenotypic RT-qPCR and for RHEV using a RT-qPCR assay followed by characterization using nested RT-PCR. Regarding wastewaters, three tested positive for HEV, while 39 out of 44 tested positive for RHEV. Wastewater analysis in the Iberian Peninsula revealed a predominance of RHEV and a near absence of HEV. The absence of both viruses was observed in the swine fecal samples. This combined analysis showing near/total absence of HEV in wastewaters/fattened swine samples warrants further studies. High levels of RHEV in wastewater might also pose environmental transmission risks, particularly for individuals with occupational exposure, emphasizing the need for enhanced zoonotic virus surveillance in urban areas.

Simulation model to estimate the burden of disease due to hepatitis E virus in Dutch pig meat and cost-effectiveness of control measures

Hepatitis E virus (HEV) can lead to liver disease in humans. In the Netherlands, the consumption of pig meat is thought to be the main contributor to the total burden of disease caused by HEV. In this study, the number of cases and lost disability-adjusted-life-years (DALYs) due to HEV in pig meat were estimated by simulating HEV through the pig supply chain, including the farm, transport, lairage, slaughtering, processing, and consumption stages. The first four stages were modeled using a susceptible-exposed-infected-recovered (SEIR) model. For the last two stages, pig meat and liver products were divided into six product categories commonly consumed by Dutch consumers. Depending on the product category, different ways of heating and storing, leading to the reduction of infectious HEV genome copies, were assumed. Furthermore, the model was challenged by four selected control options at the pig farm: the cleaning of driving boards, the use of predatory flies, the use of rubber mats, and the vaccination of finishing pigs. Finally, the cost-effectiveness of these control measures was estimated by estimating the costs per avoided DALY. For the baseline situation, it was estimated that HEV in pig meat would lead to 70 cases and 21 DALYs per year. All control measures led to a decreased number of DALYs, with vaccination leading to the largest decrease: five DALYs per year. However, the costs per avoided DALY ranged from €0.5 to €7.5 million, making none of the control measures cost-effective unless the control measures are also effective against other pathogens.

Hepatitis E Virus in the United States and Canada: Is It Time to Consider Blood Donation Screening?

Hepatitis E virus (HEV) is the most common cause of acute viral hepatitis in the world and can lead to severe complications in immunocompromised individuals. HEV is primarily transmitted through eating pork, which has led to an increased in anti-HEV IgG seropositivity in the general population of Europe in particular. However, it can also be transmitted intravenously, such as through transfusions. The growing evidence of HEV contamination of blood products and documented cases of transmission have given rise to practice changes and blood product screening of HEV in many European countries. This review covers the abundant European literature and focuses on the most recent data pertaining to the prevalence of HEV RNA positivity and IgG seropositivity in the North American general population and in blood products from Canada and the United States. Currently, Health Canada and the Food and Drug Administration do not require testing of HEV in blood products. For this reason, awareness among blood product prescribers about the possibility of HEV transmission through blood products is crucial. However, we also demonstrate that the province of Quebec has a prevalence of anti-HEV and HEV RNA positivity similar to some European countries. In light of this, we believe that HEV RNA blood donation screening be reevaluated with the availability of more cost-effective assays.

Changes in Hepatitis E Virus Contamination during the Production of Liver Sausage from Naturally Contaminated Pig Liver and the Potential of Individual Production Parameters to Reduce Hepatitis E Virus Contamination in the Processing Chain

In this study, changes in hepatitis E virus (HEV) contamination in the production of liver sausage from naturally contaminated pork liver were investigated. Furthermore, the potential effectiveness of individual production parameters in reducing viral loads was measured. When processing moderately contaminated liver (initial Cq-value 29), HEV RNA persisted in the finished sausages, even after heating for 90 min at 75 °C. A matrix-specific standard curve was created using a spiking experiment to accurately quantify HEV RNA in a particularly challenging matrix like liver sausage. Variations in product-specific production parameters, including mincing and heating times, showed some reduction in contamination levels, but even prolonged heating did not render all finished products HEV negative. The persistence of HEV contamination underscores the importance of ongoing monitoring in the pig population and raw materials to enhance food safety measures and reduce the likelihood of transmission through pork consumption. The detection of HEV RNA within all processing stages of pork liver in the production of liver sausage suggests that further research into the risk of infection posed by this detection and vigilance in managing HEV risks in the food chain, particularly in pork products, are required to protect public health.

Biosecurity measures to control hepatitis E virus on European pig farms

Hepatitis E virus (HEV) genotype 3 is a prevalent zoonotic pathogen in European pig farms, posing a significant public health risk primarily through the foodborne route. The study aimed to identify effective biosecurity measures for controlling HEV transmission on pig farms, addressing a critical gap in current knowledge. Utilizing a cross-sectional design, fecal samples from gilts, dry sows, and fatteners were collected on 231 pig farms of all farm types across nine European countries. Real-time RT-PCR was employed to test these samples for HEV. Simultaneously, a comprehensive biosecurity questionnaire captured data on various potential measures to control HEV. The dependent variable was HEV risk, categorized as lower or higher based on the percentage of positive pooled fecal samples on each farm (25% cut-off). The data were analyzed using generalized linear models (one for finisher samples and one for all samples) with a logit link function with country and farm type as a priori fixed factors. The results of the final multivariable models identified key biosecurity measures associated with lower HEV risk, which were the use of a hygienogram in the breeding (OR: 0.06, p = 0.001) and/or fattening area after cleaning (OR: 0.21, p = 0.019), the presence of a quarantine area (OR: 0.29, p = 0.025), testing and/or treating purchased feed against Salmonella (OR: 0.35, p = 0.021), the presence of other livestock species on the farm, and having five or fewer persons in charge of the pigs. Contrary to expectations, some biosecurity measures were associated with higher HEV risk, e.g., downtime of 3 days or longer after cleaning in the fattening area (OR: 3.49, p = 0.005) or mandatory handwashing for farm personnel when changing barn sections (OR: 3.4, p = 0.026). This novel study unveils critical insights into biosecurity measures effective in controlling HEV on European pig farms. The identification of both protective and risk-associated measures contributes to improving strategies for managing HEV and underscores the complexity of biosecurity in pig farming.