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The number of reported cases of human hepatitis E virus (HEV) infection has increased since 2012. Pigs are considered an important source of viruses causing human HEV infection. It is possible that the prevalence of HEV among pigs at slaughter age (approximately 6 months old) has increased in the last decade. Therefore, we investigated the current prevalence of HEV among pigs in Japan. Although HEV RNA was detected in rectal content samples from pigs aged from one to 5 months, no HEV RNA was detected in any samples from 6-month-old pigs. The highest viral shedding prevalence (33%) was detected among 3-month-old pigs. This study shows that there has been no change in the prevalence of HEV among pigs at the slaughter age, in the prevalence of HEV by age group on pig farms, or in the phylogenetic classification of HEV isolates in the last decade. Therefore, factors downstream of the pork production stage may be contributing to the increased number of human HEV infection cases.

We investigated the prevalence of Campylobacter spp., Salmonella spp., Listeria monocytogenes, and hepatitis E virus (HEV) in swine liver. We collected swine livers from 110 pigs at an abattoir from September 2011 to March 2012 [corrected] . Pathogens were detected in the liver samples of 19 (17.3%) pigs. Campylobacter spp. were isolated from the liver samples of 14 (12.7%) pigs. In 10 of the 14 Campylobacter-positive pigs, bacteria were present in the internal regions of the liver. Salmonella spp. and L. monocytogenes were detected in the liver samples of 5 (4.5%) pigs and 1 (1%) pig, respectively. No HEV was detected in the swine liver samples tested. Regarding antimicrobial resistance in Campylobacter and Salmonella isolates, all isolates, except 1 Campylobacter jejuni isolate, were resistant to 1 or more antimicrobial agent. Campylobacter spp. resistant to erythromycin and/or enrofloxacin were isolated from the liver samples of 9 (8%) pigs. These results suggest that the consuming swine liver without proper heat treatment may increase the risk of foodborne illnesses.

This study was conducted to determine the prevalence of antimicrobial resistance in Shiga toxin-producing Escherichia coli (STEC) O157 (n = 241) and O26 (n = 11) isolated from beef cattle and to characterize their antimicrobial resistance profiles. Resistance to dihydrostreptomycin was detected most frequently (STEC O157, 9.5%; STEC O26, 54.5%), followed by resistance to oxytetracycline (7.9%; 45.5%) and ampicillin (5.4%; 36.4%). Resistance to one or more antimicrobial agents was detected in 13.3% (32/241) of the STEC O157 isolates and 54.5% (6/11) of the STEC O26 isolates. The antimicrobial resistance rate in the STEC O26 isolates was significantly higher than that in the STEC O157 isolates (P = 0.002, Fisher's exact test). The antimicrobial resistance rate in the STEC O157 isolates possessing both stx(1) and stx(2) genes was 26.3% (15/57), while that in the isolates possessing stx(2c) gene alone was 3.9% (3/77). These findings suggest that the antimicrobial resistance in STEC O157 is associated with serogroups and the Shiga toxin genotype.