Risk factors associated with hepatitis E virus in pigs from different production systems

Pigs are considered important reservoirs of HEV and so constitute a major risk of transmission to humans, either via direct contact or by consuming raw or undercooked contaminated pork products. Once the scale of this disease on European pig farms has been estimated, the identification of risk factors associated with HEV infection in these species could help determine contingency strategies to minimize the risk of transmission to humans. Our objective was to evaluate risk factors associated with HEV in pigs under different production systems. We included 1040 pigs from 26 farms. The prevalence of HEV infection in the study population, evaluated by RT-qPCR, was calculated, then studied according to animal and farm characteristics. Factors associated with HEV infection were analyzed by multivariate analysis. One hundred and seventy-two pigs were infected by HEV, which gave an individual prevalence of 16.5% (95% CI: 14.4%-18.9%). Factors associated with higher prevalence of HEV infection were: extensive farming [23.9%; OR = 2.239 (1.036-4.837)], absence of sanitary ford [33.8%; OR = 3.597 (1.649-7.850)], no quarantine period [20.8%; OR = 2.723 (1.450-5.112)], and contact with domestic species [24.5%; OR = 3.893 (1.453-10.431)]. Our evidence showed that pigs reared on extensive farms are at a higher risk of HEV infection than those reared intensively. The use of control measures could reduce the risk of HEV infection in pigs and minimize the risk of zoonotic transmission.