Seroprevalence of hepatitis E virus antibodies among slaughtered pigs in Nigeria: an abattoir-based multi-state survey

Hepatitis E virus (HEV) is an emerging zoonotic pathogen in many parts of the world. Although pigs are important reservoirs of HEV, there is a paucity of multi-state data on HEV among domestic pigs (Sus scrofa domesticus) and the associated slaughter‑slab risk factors in Nigeria. This study, therefore, determined the seroprevalence of HEV antibodies among slaughtered pigs and evaluated zoonosis awareness and risk perception among pig workers across six selected Nigerian states to assess animal welfare and slaughter hygiene conditions at the sampled facilities. A multi-state cross-sectional study was conducted across six of the 36 states in Nigeria (Benue, Enugu, Kaduna, Kwara, Oyo and Plateau). Porcine plasma (n = 1,723) collected from 25 slaughter slabs was screened for total HEV antibodies using IDVET indirect multispecies ELISA. Socio-demographic data, including slaughter hygiene and animal welfare, were obtained through on-site observations, and 84 pig butchers/farmers were surveyed on awareness and risk perception of pig-borne zoonoses. Multivariable logistic regression was used to identify predictors of HEV seropositivity. Overall, HEV seroprevalence was 47.1% (n = 811), ranging from 26.0% in Kwara to 67.6% in Kaduna. In multivariable analysis, state, age, and gender were independently associated with HEV seropositivity: pigs in Kaduna (aOR = 2.10, 95% CI: 1.46-3.02; p < 0.001) and Plateau (aOR = 1.58, 95% CI: 1.10-2.27; p = 0.014) had higher odds of having anti-HEV antibodies. Older pigs aged 6-10 months (aOR = 3.40, 95% CI: 2.49-4.63) and > 10 months (aOR = 3.23, 95% CI: 2.35 - 4.44) had over three-fold higher likelihood of HEV seropositivity. Females had over three times the odds of having anti-HEV IgG compared with males (aOR = 3.23, 95% CI: 2.59-4.04). Slaughter slabs were rated average (20%, n = 5/25) or below average (36%, n = 9/25) for hygiene, with frequent faecal, blood and dirt contamination and limited use of personal protective equipment. Less than half (44%, n = 11/25) of the slaughtering facilities practised proper stunning and bleeding. Knowledge of pig-borne zoonoses among butchers/farmers was poor: 47.6% knew pigs could transmit diseases to humans, and specific disease recognition was limited. The high rates of HEV in slaughtered pigs in this study, combined with suboptimal slaughter hygiene and limited zoonoses awareness among pig workers, underscore a substantial potential for zoonotic transmission in Nigeria. Strengthening on-farm biosecurity, slaughter‑slab hygiene, and occupational health education within a One Health framework is essential to reducing HEV and other pig-associated zoonotic risks.