Table 2 Infection dynamics of HEV in pig farms, reported in eight longitudinal studies
From: Infection dynamics and persistence of hepatitis E virus on pig farms – a review
Reference | Size of study population | Age in weeks when 20% of pigs or less have maternal IgGs | Age of first shedder / viremic pig (weeks) | Age when most pigs shed HEV (weeks) | Cumulative incidence of infection (based on shedding / immune response) | Age range of detection IgG positive pigs (weeks) |
|---|---|---|---|---|---|---|
LeBlanc et al. [17] | 1 farm, 51 piglets from 51 litters | No maternal antibodies detected | 2 | 18 | 98.4% | NA |
De Deus et al. [18] | 1 litter | 9 | 1 (viremia) | 12 and 15 | NA | 15–22 |
Kanai et al. [19] | litter 1 with mat. IgG | 7 (based on ELISA index value instead of % of animals) | 4 | Continuously from 6 to 14 | 100% | 9–17 |
litter 2 without mat. IgG | No maternal antibodies detected | 4 | Continuously from 6 to 13 | 100% | 10–17 | |
Casas et al. [20] | Farm 1, 5 sows, 20 piglets | 8 (based on sampling only at week 7 and 13, no information about period in between) | 6 (estimate based on IgM) | NA | 80% (based on IgM, underestimation) | 18–25 |
Farm 2, 5 sows, 20 piglets | 12 | 12 (based on IgM) | NA | 37% (based on IgM) | 18 - NA | |
Farm 3, 5 sows, 20 piglets | 6 | 6 (based on IgM) | NA | 90% (based on IgM) | 13–18 | |
Farm 4, 5 sows, 20 piglets | 12 | 3 | NA | 53% (based on IgM) | 13 - NA | |
Farm 5, 5 sows, 20 piglets | 13 | 3 | NA | 90% (based on IgM) | 13 - NA | |
Farm 6, 5 sows, 20 piglets | 10 | 3 | NA | 100% (based on IgM) | 13 - NA | |
Feng et al. [21] | 1 farm, 32 pigs from unknown sows | 8 | Between 4 and 9 (viremia) | NA | 100% (based on seroconversion of all animals) | 11–17 |
Krog et al. [22] | group 1 and 2: low/intermediate mat. IgG | No maternal antibodies detected | 13 | 15 | 73% | 11–13 |
group 3 high mat. IgG | 7 (based on normalized OD values instead of % of pigs with IgGs) | 13 | 15 | 45% | 11–13 | |
Motoya et al. [23] | 1 farm, 7 piglets from one litter | Study started at 6 weeks of age, no maternal antibodies detected | 9 | 11–14 all shed | 100% | 11–15 |
Salines et al. [24] | Farm 1, 3 batches, 120 pigs in total | 6 (based on average optical density) | 14–18 | 19 | 41% | 18/22 - NA |
Farm 2, 3 batches, 120 pigs in total | 6 (based on average optical density) | 1 week in 1 batch; 6–10 weeks in 2 batches | 7 | 85% | 10/14 - NA | |
Farm 3, 3 batches, 120 pigs in total | 6 (based on average optical density) | 1 week in 1 batch; 10–14 weeks in 2 batches | 14 | 80% | 14/18 - NA |