Detection and characterization of swine hepatitis E virus from herds in North Carolina and Costa Rica

The evidence for the global existence of seropositive swine, genetic relatedness of swine and human isolates, inter-species transmission of swine and human strains, and high seroprevalence levels of Hepatitis E virus (BEV) antibodies amongst swine caretakers suggests a need to further examine public health risks for potential zoonotic spread of HEV.; The epidemiology of HEV infection in modern swine production systems and the extent to which HEV may be present in the fecal waste generated remains poorly characterized and has not been described in previous literature. In an attempt to address these issues, a cross-sectional study design was applied to farm sites in North Carolina (NC) and Costa Rica (CR) to represent developed and developing countries, respectively.; Despite differences in farm size, bio-security measures and other farm-related variables, all seven farms from CR and three of the five NC farms had at least one sample found to contain HEV RNA with the majority of the positive samples from pigs between the ages of 1.5 and 3 months. This represents the first evidence of HE infections in swine from Latin America. Also, HEV was detected in liquid swine waste from NC farms utilizing facultative lagoons or a treatment system consisting of a solids separator and constructed wetlands.; All isolates examined from NC and CR farms were most genetically similar within the capsid-encoding region, ORF 2, to other characterized strains of HEV belonging to genotype III. NC isolates from two different farms demonstrated approximately 91--98% nucleotide identity with US swine and human isolates compared to about 83--92% with the Canada, Japan, and CR swine strains. On the other hand, a third farm isolate most closely resembled the Japan swine HEV strain (89% nucleotide identity). The genetic diversity among the NC isolates was roughly 8%. CR isolates demonstrated 91.0--92.5% nucleotide identity with the swine and human US isolates compared to 84.4--87.7% with a Canadian swine isolate.; Phylogenetic analysis conducted with approximately 1470 ORF 2 nucleotides for a subset of the CR farm isolates revealed a distinct segregation with the human HEV isolate, US2.