DETECTION AND MOLECULAR CHARACTERIZATION OF ZOONOTIC VIRUSES IN SWINE ISOLATED IN ITALIAN PIG HERDS

Gastrointestinal disease is frequent in pigs, and among the different etiological agents involved viruses are considered the leading cause of diarrhea in this animal species. Furthermore about half of newly identified swine pathogens are viruses, most of which may be transmitted to humans by direct contact or by indirect transmission pathways. In this study, the prevalence of astrovirus (AstV), group A rotavirus (RVA), norovirus (NoV) and hepatitis E virus (HEV) infections in pigs were investigated. During 2012-2014 a total of 242 fecal samples were collected from pigs at different production stages (from 0 to 180 day-old) in eight swine farms located in northern, central and southern Italy. Seven out of 8 farms analyzed were positives for AstV, which was detected in 163/242 (67.4%) samples and represented the most prevalent virus; 61 animals (37.4%) showed diarrhea. HEV, was detected in 6 farms and in 45/242 (18.6%) of the samples analyzed. Twenty-three HEV infected pigs had diarrhea (45%). A lower prevalence was observed for RVA, only three farms resulted positives, it was found in 10/242 samples (4.13%), 6 out of these showed diarrhea (60%). On the contrary, no swine samples were found to be positive for NoV. This study compares for the first time in Italy the occurrence of astroviruses, rotaviruses and hepatitis E in a same population of pigs, and reports the molecular characterization of viral strains detected. The presence of enteric viruses also in asymptomatic swine identifies a possibly underscored risk of virus spreading among animals and addresses a potential source of infection for humans. Further studies are required in order to understand the role of these viruses in gastrointestinal diseases of pigs. Sequence analyses may permit to assess the zoonotic potential of the viruses detected in animal clinical samples.