Backyard pigs are a reservoir of zoonotic hepatitis E virus in southern Brazil.

Hepatitis E virus (HEV) is the causative agent of acute hepatitis worldwide. There is no seroprevalence study in backyard farms, which are characterized by suboptimal hygienic conditions in Brazil. We aimed to determine the seroprevalence and genetic diversity of HEV in backyard pigs in Brazil. Swine serum samples collected in 2012 (n=731) and 2014 (n=713) were analysed. The presence of anti-HEV immunoglobulin G in pig serum was evaluated by indirect enzyme-linked immunosorbent assay. Reverse transcription polymerase chain reaction was performed and phylogenetic analyses were carried out based on the partial ORF1 and ORF2 coding regions. Anti-HEV antibodies were detected in 77.6% (567/731; 95% confidence interval [CI] 74.5 to 90.6%) of serum samples in 2012 and 65.5% (467/713; 95% CI 62.0 to 69.0%) in 2014. The herd seroprevalence was 91.7% (187/204; 95% CI 91% to 99%) in 2012 and 83.7% (164/196; 95% CI 78% to 89%) in 2014. Further, HEV RNA was detected in 0.8% (6/713) of samples from 2014. Phylogenetic analysis showed three different genotype 3 subtypes with high similarity to human HEV strains. This study showed that backyard pigs are a reservoir of HEV and alerts us to the need to control infection and spillover from backyard farms. MF438128-MF438135.