Risk Profile of Hepatitis E Virus from Pigs or Pork in Canada

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.

Animal reservoirs for hepatitis E virus within the Paslahepevirus genus

Hepatitis E virus (HEV) is responsible for acute hepatitis in humans. It is a single-stranded, positive-sense RNA virus that belongs to the Hepeviridae family. The majority of concerning HEV genotypes belong to the Paslahepevirus genus and are subsequently divided into eight genotypes. HEV genotypes 1 and 2 exclusively infect humans and primates while genotypes 3 and 4 infect both humans and other mammals. Whereas HEV genotypes 5 and 6 are isolated from wild boars and genotypes 7 and 8 were identified from camels in the United Arab Emirates and China, respectively. HEV mainly spreads from humans to humans via the fecal-oral route. However, some genotypes with the capability of zoonotic transmissions, such as 3 and 4 transmit from animals to humans through feces, direct contact, and ingestion of contaminated meat products. As we further continue to uncover novel HEV strains in various animal species, it is becoming clear that HEV has a broad host range. Therefore, understanding the potential animal reservoirs for this virus will allow for better risk management and risk mitigation of infection with HEV. In this review, we mainly focused on animal reservoirs for the members of the species Paslahepevirus balayani and provided a comprehensive list of the host animals identified to date.

Swine Norovirus: Past, Present, and Future

Norovirus, an ssRNA + virus of the family Caliciviridae, is a leading disease burden in humans worldwide, causing an estimated 600 million cases of acute gastroenteritis every year. Since the discovery of norovirus in the faeces of swine in Japan in the 1990s, swine norovirus has been reported in several countries on several continents. The identification of the human-associated GII.4 genotype in swine has raised questions about this animal species as a reservoir of norovirus with zoonotic potential, even if species-specific P-types are usually detected in swine. This review summarises the available data regarding the geographic distribution of norovirus in swine, the years of detection, the genotype characterisation, and the prevalence in specific production groups. Furthermore, we discuss the major bottlenecks for the detection and characterisation of swine noroviruses.

First molecular detection of hepatitis E virus genome in camel and pig faecal samples in Ethiopia

BACKGROUND

Hepatitis E is an enteric and zoonotic disease caused by hepatitis E virus (HEV) that is mainly transmitted via the faecal-oral route through contaminated food or the environment. The virus is an emerging infectious agent causing acute human infection worldwide. A high seroprevalence of the disease was reported in pregnant women in Addis Ababa, Ethiopia, raising significant public health concern. The presence of HEV specific antibodies were also reported in dromedary camels in the country; however, the infectious virus and/or the viral genome have not been demonstrated to date in animal samples.

METHODS

To address this gap, a total of 95 faecal samples collected from both apparently healthy pigs of uncharacterised types (50 samples) in Burayu and Addis Ababa areas and camels (Camelus dromedarius, 45 samples) in west Hararghe were screened for the presence of HEV genome using universal primers in a fully nested reverse transcription polymerase chain reaction (nRT-PCR). The protocol is capable of detecting HEV in faecal samples from both pigs and camels.

RESULTS

The nRT-PCR detected HEV genes in six (12%) pig faecal samples and one camel sample (2.2%). Therefore, the results indicate that HEV is circulating in both pigs and camels in Ethiopia and these animals and their products could serve as a potential source of infection for humans.

CONCLUSION

The detection of HEV in both animals could raise another concern regarding its public health importance as both animals' meat and camel milk are consumed in the country. Further studies to determine the prevalence and distribution of the virus in different animals and their products, water bodies, food chain, and vegetables are warranted, along with viral gene sequencing for detailed genetic characterisation of the isolates circulating in the country. This information is critically important to design and institute appropriate control and/or preventive measures.

Infection dynamics and persistence of hepatitis E virus on pig farms - a review

Background

Hepatitis E virus (HEV) genotype 3 and 4 is a zoonosis that causes hepatitis in humans. Humans can become infected by consumption of pork or contact with pigs. Pigs are the main reservoir of the virus worldwide and the virus is present on most pig farms.

Main body

Though HEV is present on most farms, the proportion of infected pigs at slaughter and thus the level of exposure to consumers differs between farms and countries. Understanding the cause of that difference is necessary to install effective measures to lower HEV in pigs at slaughter. Here, HEV studies are reviewed that include infection dynamics of HEV in pigs and on farms, risk factors for HEV farm prevalence, and that describe mechanisms and sources that could generate persistence on farms. Most pigs become infected after maternal immunity has waned, at the end of the nursing or beginning of the fattening phase. Risk factors increasing the likelihood of a high farm prevalence or proportion of actively infected slaughter pigs comprise of factors such as farm demographics, internal and external biosecurity and immunomodulating coinfections. On-farm persistence of HEV is plausible, because of a high transmission rate and a constant influx of susceptible pigs. Environmental sources of HEV that enhance persistence are contaminated manure storages, water and fomites.

Conclusion

As HEV is persistently present on most pig farms, current risk mitigation should focus on lowering transmission within farms, especially between farm compartments. Yet, one should be aware of the paradox of increasing the proportion of actively infected pigs at slaughter by reducing transmission insufficiently. Vaccination of pigs may aid HEV control in the future.

A qualitative program evaluation of the Publicly Available International Foodborne Outbreak Database

Background

The Publicly Available International Foodborne Outbreak Database (PAIFOD) is a regularly updated repository that contains international outbreak data collected from multiple surveillance systems and sources. As of February 2020, the database contained more than 13,000 entries spanning over 20 years. PAIFOD is the only known database that captures international foodborne outbreak data.

Objective

To explore user perceptions and identify potential directions for PAIFOD and make recommendations for databases with food safety information.

Methods

Between January and March 2020, 16 semistructured telephone interviews were conducted with 24 previous, current and potential PAIFOD users. Interviewees were asked about their knowledge of and experience of using PAIFOD as well as about its strengths and limitations and recommendations for the database. An inductive thematic analysis approach was used to analyze qualitative data and generate themes.

Results

Four main themes were generated based on the 24 interviewees' accounts of their experience with and recommendations for PAIFOD: participants viewed PAIFOD as a useful tool; they weren't familiar with its contents or purpose; they stated it should become an open-access platform or linked with another information-sharing initiative; and they considered that PAIFOD had the potential to enhance the Agency's reputation by becoming widely recognized and used.

Conclusion

This work, along with the ever-changing landscape of foodborne surveillance, supports the need to ensure that PAIFOD is updated to meet the modern-day demands of food safety experts.

Critical Analysis of Pork QMRA Focusing on Slaughterhouses: Lessons from the Past and Future Trends

Foodborne microbial diseases have a significant impact on public health, leading to millions of human illnesses each year worldwide. Pork is one of the most consumed meat in Europe but may also be a major source of pathogens introduced all along the farm-to-fork chain. Several quantitative microbial risk assessment (QMRA) have been developed to assess human health risks associated with pork consumption and to evaluate the efficiency of different risk reduction strategies. The present critical analysis aims to review pork QMRA. An exhaustive search was conducted following the preferred reporting items for systematic reviews and meta-analyses (PRISMA) methodology. It resulted in identification of a collection of 2489 papers including 42 on QMRA, after screening. Among them, a total of 29 studies focused on Salmonella spp. with clear concern on impacts at the slaughterhouse, modeling the spreading of contaminations and growth at critical stages along with potential reductions. Along with strict compliance with good hygiene practices, several potential risk mitigation pathways were highlighted for each slaughterhouse step. The slaughterhouse has a key role to play to ensure food safety of pork-based products but consideration of the whole farm-to-fork chain is necessary to enable better control of bacteria. This review provides an analysis of pork meat QMRA, to facilitate their reuse, and identify gaps to guide future research activities.

Swine hepatitis E virus: Cross-species infection, pork safety and chronic infection

Swine hepatitis E virus (swine HEV) belongs to the species Orthohepevirus A within the genus Orthohepevirus in the family Hepeviridae. Four different genotypes of swine HEV within the species Orthohepevirus A have been identified so far from domesticated and wild swine population: genotypes 3 (HEV-3) and 4 (HEV-4) swine HEVs are zoonotic and infect humans, whereas HEV-5 and HEV-6 are only identified from swine. As a zoonotic agent, swine HEV is an emerging public health concern in many industrialized countries. Pigs are natural reservoir for HEV, consumption of raw or undercooked pork is an important route of foodborne HEV transmission. Occupational risks such as direct contact with infected pigs also increase the risk of HEV transmission in humans. Cross-species infection of HEV-3 and HEV-4 have been documented under experimental and natural conditions. Both swine HEV-3 and swine HEV-4 infect non-human primates, the surrogates of man. Swine HEV, predominantly HEV-3, can establish chronic infection in immunocompromised patients especially in solid organ transplant recipients. The zoonotic HEV-3, and to lesser extent HEV-4, have also been shown to cause neurological diseases and kidney injury. In this review, we focus on the epidemiology of swine HEV, host and viral determinants influencing cross-species HEV infection, zoonotic infection and its associated pork safety concern, as well as swine HEV-associated chronic infection and neurological diseases.

Cross-sectional Seroprevalence and Genotype of Hepatitis E Virus in Humans and Swine in a High-density Pig-farming Area in Central China

Hepatitis E virus (HEV) infection is a common public health problem in developing countries. However, the current prevalence of HEV and the relationship of HEV genotype between swine and human within high-density pig-farming areas in central China are still inadequately understood. Here, cross-sectional serological and genotypic surveys of HEV among the 1232 general population, 273 workers occupationally exposed to swine, and 276 pigs in a high-density pig-breeding area, were undertaken by ELISA and nested RT-PCR methods. Anti-HEV IgG was detected in 26.22% of general population and 48.35% of occupational workers. The prevalence of swine serum HEV-Ag was 6.52%. The prevalence of anti-HEV IgG was significantly higher among the workers occupationally exposed to swine than among the general population. An increased HEV seropositivity risk among the general population was associated with either being a peasant or male and was very strongly associated with the increase of age. Among the occupationally exposed group, the prevalence of anti-HEV IgG antibodies increased with age and working years. Among the 30 HEV-IgM-positive people, the infection rates of clerks in the public, peasants, pork retailers, and pig farmers were higher than those of others. A phylogenetic analysis revealed that all the isolates belonged to subgenotype 4_d, and four people and four pigs shared 97.04%-100% sequence homology. This study revealed a high HEV seroprevalence among the general population and workers occupationally exposed to swine in the Anlu City, and supports the notion that swine are a source of human HEV infection.

Hiding in Plain Sight? It's Time to Investigate Other Possible Transmission Routes for Hepatitis E Virus (HEV) in Developed Countries

Historically in developed countries, reported hepatitis E cases were typically travellers returning from countries where hepatitis E virus (HEV) is endemic, but now there are increasing numbers of non-travel-related ("autochthonous") cases being reported. Data for HEV in New Zealand remain limited and the transmission routes unproven. We critically reviewed the scientific evidence supporting HEV transmission routes in other developed countries to inform how people in New Zealand may be exposed to this virus. A substantial body of indirect evidence shows domesticated pigs are a source of zoonotic human HEV infection, but there is an information bias towards this established reservoir. The increasing range of animals in which HEV has been detected makes it important to consider other possible animal reservoirs of HEV genotypes that can or could infect humans. Foodborne transmission of HEV from swine and deer products has been proven, and a large body of indirect evidence (e.g. food surveys, epidemiological studies and phylogenetic analyses) support pig products as vehicles of HEV infection. Scarce data from other foods suggest we are neglecting other potential sources of foodborne HEV infection. Moreover, other transmission routes are scarcely investigated in developed countries; the role of infected food handlers, person-to-person transmission via the faecal-oral route, and waterborne transmission from recreational contact or drinking untreated or inadequately treated water. People have become symptomatic after receiving transfusions of HEV-contaminated blood, but it is unclear how important this is in the overall hepatitis E disease burden. There is need for broader research efforts to support establishing risk-based controls.