Table 1 Quantified risk factors associated with a high HEV seroprevalence in pig farms

Di Bartolo et al. [18]

Number of sows > 1000: HEV seroprevalence = 54.2 vs 18.9%

Li et al. [21]

HEV seroprevalence on family-scale farms = 90 vs 76% in large-scale farms (p < 0.01)

Jinshan et al. [15]

Number of pigs > 600: HEV seroprevalence ranged from 78 to 100%, vs 0 to 29%

Hinjoy et al. [20]

Medium-sized farms compared with large farms: OR 4.95 (1.79–13.70)

Presence of bird faeces inside the pig house: OR 2.87 (1.07–7.71)

Walachowski et al. [23]

Duration of the nursery down period < 4 days: OR 1.7 (1.04–2.9)

Distance between pit manure and slatted floor in fattening premises < 80 cm: OR 1.9 (1.1–3.5)

Mingling of pigs from different premises between farrowing and nursery stages: OR 1.8 (1.1–2.9)

Pen size in nursery rooms > 26 pigs/pen: OR 2.4 (1.2–4.8)

Rutjes et al. [22]

HEV seroprevalence on organic farms = 89 vs 72% on conventional farms (p = 0.04)

HEV seroprevalence on free-range farms = 76 vs 72% on conventional farms (p = 0.06)