Pig Handlers Research Articles

High Hepatitis E Virus Seroprevalence in Forestry Workers and in Wild Boars in France

Hepatitis E virus (HEV) is a fecally and orally transmitted human pathogen of worldwide distribution. In industrial countries, HEV is observed in an increasing number of autochthonous cases and is considered to be an emerging pathogen. A growing body of evidence suggests that HEV is a zoonotic disease, and pig handlers and pig veterinarians have been reported to be high-risk groups for HEV infection. The aims of the present study were to establish the prevalence of anti-HEV in wild boars in France and to identify whether forestry workers are at a higher risk of HEV infection. Three different anti-HEV tests were used to compare their effectiveness in detecting anti-HEV in the general population. The most sensitive test was then used to investigate HEV seroprevalence in 593 forestry workers and 421 wild boars. Anti-HEV was detected in 31% of the forestry workers and 14% of the wild boars. Detection of anti-HEV in humans was correlated with age, geographical location, and occupational activity and in wild boars was correlated with geographical location. HEV infection is frequent in woodcutters in France, and it varies geographically. Further studies are needed to confirm these findings and to elucidate the transmission route and the exact virus reservoirs.

Comparative Exoproteome Profile of MRSA-ST9 Isolated from Pigs and Pig Handler

MRSA-ST9-t4358 from pigs and pig handlers were analysed for exoproteins profiles. Similar protein patterns with variation in protein spot intensity were observed. No significant variation among the protein profiles indicates that transmission of MRSA-ST9 from pig to human or vice versa, do not strongly alter the gene expression patterns. Indirectly, virulence factors that acquired from pig environment might have chance to be expressed in human host.

Unexpected elevated alanine aminotransferase, aspartate aminotransferase levels and hepatitis E virus infection among persons who work with pigs in accra, Ghana.

BackgroundSeveral studies have suggested that elevated serum alanine aminotransferase (ALT) and asparte aminotransferase (AST) may be markers of hepatitis E virus (HEV) infection. Thus, individuals with elevated ALT and AST may have ongoing subclinical infection of HEV. We estimated the prevalence of anti-HEV antibodies and serum ALT and AST levels among persons who work with pigs in Accra, Ghana.ResultsThree hundred and fifty- persons who work with pigs provided blood samples for unlinked anonymous testing for the presence of antibodies to HEV, ALT and AST levels. The median age of participants was 32.85 ± 11.38 years (range 15-70 years). HEV seroprevelance was 34.84%. Anti-HEV IgG was detected in 19.26% while anti-HEV IgM was detected in 15.58% of the persons who tested positive. On multivariate analysis, the independent determinants of HEV infection were, being employed on the farm for less than six months [odds ratio (OR) 8.96; 95% confidence interval (95% CI) 5.43-14.80], having piped water in the household and/or on the farm (OR 13.33; 95% CI 5.23-33.93) and consumption of alcohol (OR 4.91: 95% CI 2.65-9.10). Levels >3× the expected maximum were found for both ALT and AST among individuals who tested positive for anti-HEV IgG (ALT, 210.17 ± 11.64 U/L; AST, 127.18 ± 11.12 U/L) and anti-HEV IgM (ALT, 200.97 ± 10.76 U/L; AST, 120.00 ± 15.96 U/L).ConclusionConsistent with similar studies worldwide, the results of our studies revealed a high prevalence of HEV infection, ALT and AST values in pig handlers.

Detection of Haemagglutination–Inhibiting Antibodies against Human H1 and H3 Strains of Influenza A Viruses in Pigs in Ibadan, Nigeria

Agricultural and commercial activities have continued to bring people and pigs into regular, close contact in Ibadan, Nigeria. This study was therefore designed to investigate the transmission of human influenza viruses to pigs in Ibadan, using serological surveillance. Serum specimens were collected from ninety-one (91/199) apparently healthy, unvaccinated Landrace pigs at three locations within Ibadan from April to June, 2008. Two strains of human influenza virus A: A/Brisbane/59/2007 (H1N1) and A/Brisbane/10/2007 (H3N2) were used in Haemagglutination-Inhibition Assay for antibody detection. Prevalence of HI antibodies to the two subtypes was 90.1%. Antibodies to influenza A/Brisbane/59/2007 (H1N1) were significantly (P < 0.05) more prevalent (80.2%) than those of influenza A/Brisbane/10/2007 (H3N2) (51.6%). Titres of HI antibodies to influenza A/Brisbane/59/2007 [mean = 3331.5] were significantly higher (P < 0.05) than those of influenza A/Brisbane/10/2007 [mean = 2212.3]. This study shows that these pigs were exposed to human strains of influenza A(H1N1) and A(H3N2) either prior to or during this study. The implications of these high prevalence and antibody titres are discussed in relation to influenza virus infection among pig handlers in Ibadan, Nigeria. We recommend that periodic investigation of circulating strains of influenza viruses in pigs and humans who handle pigs regularly in Nigeria and molecular characterization of such isolates be carried out to ensure early detection of interspecies transmission and potential future pandemic strains.

Heatitis E virus infection among pig handlers in Accra, Ghana

To determine the correlates of hepatitis E virus infection (HEV) in a sample of persons who work with pigs. Cross-sectional study. Three pig farms in the Greater Accra Region of Ghana. Persons who work with pigs seen at the selected pig farms between the months of January and May 2008. One hundred and five persons who work with pigs voluntarily completed a risk-factor questionnaire and provided blood samples for unlinked anonymous testing for the presence of antibodies to HEV. The median age of participants was 36.5 +/- 15.0 years (range 12-65 years). Of the 105 subjects tested, HEV seroprevelance was 38.1%. On multivariate analysis, the independent determinants of HEV infection were being employed on the farm for less than six months (odds ratio (OR) 9.1; 95% confidence interval (95% CI) 1.0-81.4 and having piped water in the household and/or on the farm (OR 3.9; 95% CI 0.4-90.8). Consistent with similar studies worldwide, the results of our studies revealed a high prevalence of HEV infection in persons who work with pigs. Further studies need to be done to isolate, characterise the virus and define the clinical and epidemiological significance of HEV infection in this population.

Prevalence of ST9 Methicillin-Resistant Staphylococcus aureus among Pigs and Pig Handlers in Malaysia

Methicillin-resistant Staphylococcus aureus (MRSA) of sequence type 398 (ST398) has frequently been detected in pigs and pig handlers. However, in Malaysia, sampling 360 pigs and 90 pig handlers from 30 farms identified novel ST9-spa type t4358-staphylococcal cassette chromosome mec type V MRSA strains that were found to transiently colonize more than 1% of pigs and 5.5% of pig handlers.

Operational Trials of Remote Mosquito Trap Systems for Japanese Encephalitis Virus Surveillance in the Torres Strait, Australia

Japanese encephalitis virus (JEV) appears nearly annually in the Torres Strait in far northern Queensland, Australia, and is a threat to invade the Australian mainland. Surveillance has involved the use of sentinel pigs that develop detectable viremias and antibody titers to JEV. However, pigs are amplifying hosts for JEV, and thus pose a health risk to the public and to pig handlers who bleed the pigs. A remote mosquito trap system would not have these risks. We report on trials using a remote mosquito trap system for the surveillance of JEV in the Torres Strait. The Mosquito Magnet (MM) Pro, MM Liberty Plus, and a novel updraft trap, the NAQS Mozzie Trap, were run at Badu and Moa islands in the Torres Strait and at Bamaga in the northern Cape York Peninsula from 2002-2005. TaqMan real-time polymerase chain reaction (PCR) was used to detect JEV nucleic acid in weekly mosquito collections. Sentinel pigs located at Badu were also bled and the serum processed by reverse transcriptase (RT)-PCR for JEV antigen and enzyme-linked immunosorbent assay (ELISA) for anti-JEV antibodies. JEV was detected in mosquito collections each year but not in each trap. No JEV was detected in trapped mosquitoes before detection in sentinel pigs. The mosquito trap system cost ca. AU$10,000 per site, about AU$5,000 less than a pig-based system. However, trap failures caused by mosquito-clogged motors, electrical faults, and blocked gas lines reduced the efficacy of some mosquito traps. Nonetheless, a remote mosquito trap system, employing stand alone traps and PCR for viral antigen detection, can be a safe, economical way to detect arbovirus activity in remote areas.

Serological evidence of hepatitis E virus infection in different animal species from the Southeast of Brazil

Serological evidence of hepatitis E virus infection (HEV) has been observed in both humans and different animal species living in non-endemic areas, suggesting that animals could be important reservoir for virus transmission to man. Antibodies to HEV have been detected in some Brazilian population groups. Nevertheless, sporadic cases of acute HEV infection have never been reported. We collected 271 serum samples from several domestic animals and also from pig handlers from Southeast of Brazil in order to investigate the seroprevalence of HEV infection. Anti-HEV IgG was detected in cows (1.42%), dogs (6.97%), chickens (20%), swines (24.3%), and rodents (50%), as well as in pig handlers (6.3%). The recognition of swine HEV infections in pigs in many countries of the world led us to investigate a larger sample of pigs (n = 357) from the same Brazilian region with ages ranging from 1 to > 25 weeks. IgG anti-HEV was detected in 100% of 7-day old pigs. Following a gradual decline between weeks 2 and 8 (probably due to loss of maternal IgG), the prevalence then steady increased until it reached 97.3% of animals older than 25 weeks. Besides the detection of anti-HEV antibodies in different animal species, the results showed that swine HEV infection seems to be almost universal within this Brazilian pig population. This is the first report that shows evidences of HEV circulation in Brazilian animal species and pig handlers.

Hepatitis E virus: Cross-species infection and zoonotic risk

Abstract Hepatitis E virus (HEV), the causative agent of hepatitis E, is an important human pathogen responsible for a major proportion of enterically transmitted cases of acute viral hepatitis in many developing countries. Among the known hepatitis viruses, the high mortality rate of up to 25% observed in pregnant women is unique to HEV. Recent studies have shown that a significant proportion of healthy individuals in the United States and many other industrialized countries are positive for HEV antibodies, although acute hepatitis E occurs only sporadically in these countries. Increasing data have indicated that hepatitis E is a zoonotic disease, and that there exist animal reservoirs for HEV. Animal strains of HEV, antigenically and genetically related to human HEV, have been isolated and characterized from pigs (swine HEV) and chickens (avian HEV). Human HEV, swine HEV, and avian HEV have all been shown to infect across species. In addition to pigs and chickens, antibodies to HEV have also been detected in a number of other animal species, including rodents, chickens, dogs, cats, sheep, goats, cattle, and non-human primates; suggesting that these animal species have been exposed to HEV or a related agent. However, thus far, pigs are the only recognized potential animal reservoirs for HEV. It has been shown that pig handlers are at increased risk of zoonotic HEV infection. More recently, sporadic and cluster cases of acute hepatitis E have been linked to the consumption of raw or undercooked pig and deer meats, thus providing more direct evidence of zoonotic HEV transmission. This article briefly reviews the animal strains of HEV, their ability to infect across species, and potential zoonotic risks.

Molecular investigation of hepatitis E virus infection in domestic and miniature pigs used for medical experiments.

Hepatitis E virus (HEV) infection is highly prevalent among domestic pigs in Japan. It has been reported that pig handlers such as farmers and veterinarians are at increased risk of contracting HEV infection. Pigs are regarded as the most acceptable candidate animals for xenotransplantation and, recently, they are being used as experimental animals. We investigated the prevalence of IgG class antibodies to swine HEV (anti-HEV) and HEV RNA among 152 2-month-old domestic pigs and 38 miniature pigs of 4 to 10 months of age that had been brought to our center for medical experiments from five swine farms (A-E) in Japan. Serum samples were tested for anti-HEV by in-house enzyme immunoassay, and for HEV RNA by reverse transcription-polymerase chain reaction using primers targeting the open reading frame 2 (ORF2) region. One percent (one of 84), 6% (one of 16), and 38% (20 of 52) of the domestic pigs from farms A, B and C, respectively, had detectable HEV RNA, and the 22 HEV isolates recovered from the viremic pigs were 89.8 to 100% identical to each other in the 412-nucleotide sequence of ORF2 and segregated into three clusters within genotype 3. Although one pig from farm A had detectable HEV RNA reproducibly, the HEV isolate recovered from this pig was up to 100% similar to those recovered from pigs from farm C, and the sera from all 84 pigs from farm A were negative for anti-HEV. These results suggested that farm A is free from HEV infection. As the viremic pig from farm A had been raised for 1 month in a barn at our center before serum sampling, it is most likely that the pig acquired HEV infection in the barn at our center where HEV-viremic pigs from farm C had been reared for several days approximately 3 months earlier. The 38 miniature pigs from farms D and E were negative for both anti-HEV and HEV RNA. In an attempt to further investigate the prevalence of HEV infection, pigs that were being raised in four swine farms (farms A, C, D, and E) were tested for anti-HEV. Although 96 (86%) of the 112 pigs from farm C were positive for anti-HEV, none of the 48 pigs in farm A and 138 miniature pigs in farms D and E was positive for anti-HEV. These results suggest that three of the five swine farms tested were free from HEV, and that periodic testing for anti-HEV and HEV RNA of pigs used as experimental animals and pigs raised in swine farms from which pigs are purchased, is useful for providing HEV-free pigs to researchers who are engaged in studies using pigs.

Swine hepatitis E virus: cross-species infection and risk in xenotransplantation.

Swine hepatitis E Virus (swine HEV), a ubiquitous agent recently discovered in pigs, is antigenically and genetically closely related to the human HEV. Swine HEV infection in pigs generally occurs at about 2-3 months of age, and about 80%-100% of the pigs in commercial farms in the USA were infected. Swine HEV infections have now been recognized in pigs in many other countries of the world. Interspecies transmission has been documented, as swine HEV infects non-human primates and some strains of human HEV infect pigs. Recent seroepidemiological studies showed that swine veterinarians and other pig handlers are at higher risk of HEV infection compared to normal blood donors. In addition, novel strains of human HEV recovered from hepatitis patients in the USA, Japan and Taiwan are genetically more closely related to strains of swine HEV from respective countries than to other strains of human HEV. The ubiquitous nature of the virus in pigs and the demonstrated ability of cross-species infection raise a potential concern for swine HEV infection in xenotransplantation with pig organs. This chapter discusses the recent advances in HEV research with emphases on potential zoonosis and xenozoonosis.

Nipah Virus Infection: Pathology and Pathogenesis of an Emerging Paramyxoviral Zoonosis

In 1998, an outbreak of acute encephalitis with high mortality rates among pig handlers in Malaysia led to the discovery of a novel paramyxovirus named Nipah virus. A multidisciplinary investigation that included epidemiology, microbiology, molecular biology, and pathology was pivotal in the discovery of this new human infection. Clinical and autopsy findings were derived from a series of 32 fatal human cases of Nipah virus infection. Diagnosis was established in all cases by a combination of immunohistochemistry (IHC) and serology. Routine histological stains, IHC, and electron microscopy were used to examine autopsy tissues. The main histopathological findings included a systemic vasculitis with extensive thrombosis and parenchymal necrosis, particularly in the central nervous system. Endothelial cell damage, necrosis, and syncytial giant cell formation were seen in affected vessels. Characteristic viral inclusions were seen by light and electron microscopy. IHC analysis showed widespread presence of Nipah virus antigens in endothelial and smooth muscle cells of blood vessels. Abundant viral antigens were also seen in various parenchymal cells, particularly in neurons. Infection of endothelial cells and neurons as well as vasculitis and thrombosis seem to be critical to the pathogenesis of this new human disease.

Emerging and re-emerging epidemic encephalitis: a tale of two viruses.

Two major epidemics of viral encephalitis occurred in Asia in 1997 and 1998. The first was a re-emergence of neurovirulent strains of enterovirus 71, which caused severe encephalomyelitis in children in Malaysia, Taiwan and Japan, on a background of hand, foot and mouth disease. Necropsy studies of patients who died of enterovirus 71 infection showed severe perivascular cuffing, parenchymal inflammation and neuronophagia in the spinal cord, brainstem and diencephalon, and in focal areas in the cerebellum and cerebrum. Although no viral inclusions were detected, immunohistochemistry showed viral antigen in the neuronal cytoplasm. Inflammation was often more extensive than neuronal infection, suggesting that other factors, in addition to direct viral cytolysis, may be involved in tissue damage. The second epidemic of viral encephalitis was the result of a novel paramyxovirus called Nipah, which mainly involved pig handlers in Malaysia and Singapore. Pathological evidence suggested that the endothelium of small blood vessels in the central nervous system was particularly susceptible to infection. This led to disseminated endothelial damage and syncytium formation, vasculitis, thrombosis, ischaemia and microinfarction. However, there was also evidence of neuronal infection by the virus and this may also have contributed to the neurological dysfunction in Nipah encephalitis. Some patients who seemed to recover from the acute symptoms have been re-admitted with clinical findings suggestive of relapsing encephalitis. As these two epidemics indicate, the emergence and re-emergence of viral encephalitides continue to pose considerable challenges to the neuropathologist, in establishing the diagnosis and unravelling the pathogenesis of the neurological disease.

Prevalence of antibodies to the hepatitis E virus in pigs from countries where hepatitis E is common or is rare in the human populationThis article is a US Government work and, as such, is in the public domain in the United States of America

Hepatitis E virus (HEV) is a very important public health concern in many developing countries where epidemics of hepatitis E are common. Sporadic cases of clinical hepatitis E not only occur in these countries but also occur uncommonly in patients with no known epidemiological exposure to HEV in industrialized countries. The source of infection in industrialized countries is unknown but it has been suggested that animals might serve as a reservoir for HEV in both settings. We recently identified and characterized an HEV strain (swine HEV) that infects large numbers of pigs in the United States. To assess the potential of pigs to serve as a global reservoir of HEV, we measured the prevalence of HEV antibodies in pigs in two countries where hepatitis E is endemic and two countries where it is not. Swine herds in all four countries contained many pigs that were seropositive for IgG anti-HEV, although the percentage of seropositive pigs varied greatly from herd to herd. A very limited number of pig handlers in the two endemic countries were also tested and most of them were found to be seropositive for HEV. The results from this study suggest that hepatitis E is enzootic in pigs regardless of whether HEV is endemic in the respective human population. J. Med. Virol. 59:297–302, 1999. Published 1999 Wiley-Liss, Inc.

Prevalence of antibodies to the hepatitis E virus in pigs from countries where hepatitis E is common or is rare in the human population

Hepatitis E virus (HEV) is a very important public health concern in many developing countries where epidemics of hepatitis E are common. Sporadic cases of clinical hepatitis E not only occur in these countries but also occur uncommonly in patients with no known epidemiological exposure to HEV in industrialized countries. The source of infection in industrialized countries is unknown but it has been suggested that animals might serve as a reservoir for HEV in both settings. We recently identified and characterized an HEV strain (swine HEV) that infects large numbers of pigs in the United States. To assess the potential of pigs to serve as a global reservoir of HEV, we measured the prevalence of HEV antibodies in pigs in two countries where hepatitis E is endemic and two countries where it is not. Swine herds in all four countries contained many pigs that were seropositive for IgG anti-HEV, although the percentage of seropositive pigs varied greatly from herd to herd. A very limited number of pig handlers in the two endemic countries were also tested and most of them were found to be seropositive for HEV. The results from this study suggest that hepatitis E is enzootic in pigs regardless of whether HEV is endemic in the respective human population. J. Med. Virol. 59:297-302, 1999. Published 1999 Wiley-Liss, Inc.