Investigation of Hepatitis E virus seroprevalence in fattening pigs in Taiwan.

Hepatitis E virus (HEV) is an important zoonotic pathogen and a major cause of acute viral hepatitis worldwide. Domestic pigs are the primary reservoir of zoonotic HEV genotypes 3 and 4, making surveillance in pig populations important for understanding HEV epidemiology. However, updated data on HEV seroprevalence in Taiwanese pig populations remain limited. This cross-sectional study investigated the seroprevalence of HEV among fattening pigs in Taiwan. A total of 356 serum samples were collected from 32 commercial farms across five major pig-producing counties during 2024-2025 and tested for anti-HEV IgG by ELISA. Serum samples with sufficient residual volume (n = 274) were further tested for HEV RNA using RT-qPCR, and no HEV RNA-positive samples were detected. The overall individual-level seroprevalence was 57.6% (205/356, 95% CI: 52.4-62.7%), while 90.6% (29/32) of farms had at least one seropositive pig. Seroprevalence increased significantly with production stage, from 44.4% in early fattening pigs to 58.8% in middle and 66.5% in late fattening pigs. Compared with early fattening pigs, the odds of seropositivity were higher in middle fattening stages (OR = 2.89, 95% CI: 1.50-5.59) and late (OR = 5.24, 95% CI: 3.62-7.58). These findings demonstrate widespread HEV seropositivity among fattening pigs in Taiwan, suggesting that HEV infection commonly occurs before market age. The absence of detectable HEV RNA in serum is consistent with the transient nature of viremia reported in previous studies. Continued surveillance integrating both serological and molecular approaches, particularly including fecal samples for molecular testing, is warranted to better characterize HEV epidemiology in Taiwanese pig populations.