Increasing Hepatitis E Virus Seroprevalence in Domestic Pigs and Wild Boar in Bulgaria

Abstract

(1) Background: Hepatitis E virus (HEV) is a causative agent of acute viral hepatitis, predominantly transmitted by the fecal–oral route. In developed countries, HEV is considered to be an emerging pathogen since the number of autochthonous cases is rising. Hepatitis E is a viral disease with a proven zoonotic potential for some of its genotypes. The main viral reservoirs are domestic pigs and wild boar. Consumption of undercooked meat, as well as occupational exposure, are key factors for the spread of HEV. In order to evaluate the risks of future viral evolution, a detailed examination of the ecology and distribution of the virus is needed. The aim of the present study is to investigate the prevalence of anti-HEV IgG Ab in domestic pigs and wild boar in Bulgaria; (2) Methods: In this study, during the period of three years between 2017 and 2019, 433 serum samples from 19 different pig farms and 1 slaughterhouse were collected and analyzed. In addition, 32 samples from wild boar were also collected and analyzed during the 2018–2019 hunting season. All samples were analyzed by commercial indirect ELISA; (3) Results: Overall, HEV seroprevalence was 60% (95% CI 42.7–77.1) in domestic pigs and 12.5% (4/32) in wild boar. The observed seroprevalence of the slaughter-aged pigs was 73.65% (95% Cl 58.7–87.3). Prevalence in domestic pigs was significantly higher in the samples collected during 2019 (98% (95% Cl 96.1–99.9)) compared to those collected during 2017 (45.33% (95% CI 2.7–87.3)) and 2018 (38.46% (95% CI 29.1–49.7.); (4) Conclusions: Our findings suggest that domesticated pigs and wild boar might be the reason for the increased HEV transmission across Bulgaria. The genotypic characterization of HEV found in pigs, wild boar and humans will give a more accurate view of the zoonotic transmission of this virus.

High Seroprevalence of Hepatitis E Virus Infection Among East Balkan Swine (Sus scrofa) in Bulgaria: Preliminary Results

“…We supposed that EBS are more likely to become infected with HEV from domestic pigs. HEV seropositivity among domestic pigs in those districts is high, around 77.14-80.0% (slaughter-aged pigs, 6 months old) [7]. The HEV seroprevalence in wild boars in those districts has not yet been studied.…”

“…In 2019, a detailed seroprevalence study of HEV infection in pigs from southern Bulgaria documented an overall HEV seroprevalence of 60.3% (217 of all 360 tested sera) [6]. Takova et al, reported that 4 of the 32 meat juice samples from Bulgarian wild boar were positive for anti-HEV IgG antibodies [7]. The study of these authors had several important limitations: the research included a relatively small number of wild boars (n = 32), and information regarding their age and sex were not recorded.…”

Surveillance Study of Hepatitis E Virus (HEV) in Domestic and Wild Ruminants in Northwestern Italy

“…In Europe, investigations performed in swine herds revealed seroprevalences estimated between 30% and 100% [14][15][16][17][18][19][20][21][22][23] with molecular detection rates of 0.9% to 87.5% [24][25][26][27][28][29][30][31][32][33]. Similarly, epidemiological studies performed in wild boar populations reported antibody detection rates ranging from 12.5% to 57.4% and molecular prevalence of 0.3% to 68.2% [12,19,[34][35][36][37][38]. Transmission from deer to humans has also been described [39,40], although they mostly undergo spill-over HEV infections in contaminated habitat shared with wildlife reservoirs [12,41].…”

Efficient Production of Chimeric Hepatitis B Virus-Like Particles Bearing an Epitope of Hepatitis E Virus Capsid by Transient Expression in Nicotiana benthamiana

“…In developed counties, in the past decade, a number of autochthonous cases of HEV infection has been reported, and evidence for zoonotic transmission has been discovered [ 4 ]. The main HEV reservoirs are domestic pigs and wild boar [ 5 , 6 ]. Occupational exposure, as well as consumption of undercooked pork meat, are key factors for the spread of HEV in Europe [ 7 , 8 ].…”