| dc.description.abstract | Hepatitis E virus (HEV) is virus persistently present on most pig farms, which can infect both pigs and humans. Therefore, investigation of within-farm transmission of HEV is vital. Recent research suggests that investigating the variation of HEV infection on batch-level is promising to identify potentially effective mitigation measures. This study aimed to identify risk factors associated with occurrence of HEV-free batches of slaughter pigs on infected farms. Considering the faecal-oral transmission route of HEV, it was decided to focus on risk factors regarding between-batch transmission within farm compartments. A retrospective case-control study was performed on 73 Dutch pig farms. The presence of potential risk factors on farms was determined using a questionnaire and farm hygiene inspection. A total of 136 potential risk factors were investigated using an aggregated logistic regression modelling approach with the ratio of HEV-free and HEV-infected batches of slaughter pigs per farm as the outcome variable. The best model fit was achieved by the model containing the potential risk factors ‘building year of the oldest barn’, ‘the washing frequency of clothes’, ‘cleaning procedure includes sweeping of the floor of the central corridor’. Since this study identifies associations, the causal mechanisms underlying these findings need to be studied before effective mitigation strategies can be identified.
Hepatitis E virus (HEV) is a zoonotic virus that is persistently present on most pig farms. The epidemiology of HEV on pig farms remains to be elucidated. Considering the persistent presence of HEV on pig farms, it has been indicated that mitigation of HEV on pig farms should be focussing on within-farm transmission. The R0 of HEV is high and transmission between pigs occurs through the faecal-oral transmission route, resulting in inevitable transmission of HEV within pens. Consequently, we suggest that epidemiological research with a pen housing pigs may be promising. This study aims to enable pen-level epidemiological studies. Therefore, a cross-sectional exploration of the pen-level prevalence of HEV-shedding pigs was carried out. Faecal swab samples were taken from pigs in four age categories on four Dutch pig farms. Both the proportion of pens housing HEV shedding animals (between-pen prevalence) and the proportion of HEV shedding animals in positive tested pens (within-pen prevalence) were determined. Additionally, the prevalence of HEV-shedding pigs on farm-level and age cohort-level was calculated. HEV-shedding animals were identified on three of the four investigated farms, all in the age category ‘last week of fattening phase’. Both the between-pen prevalence and within-pen prevalence varied greatly between farms. The between-pen prevalence and within-pen ranged from 0 to 0.75 and 0.14 to 1, respectively. These results indicate that pen-level epidemiological research is not only a promising, but also a feasible method. Future research should take into account that HEV transmission dynamics may vary between farms. | |
