Cross-sectional survey of risk factors for edema disease Escherichia coli (EDEC) on commercial pig farms in Germany

Edema disease (ED) in swine, usually caused by certain Shiga toxin-producing Escherichia coli (EDEC) in the first few weeks after weaning, has a high mortality rate in affected piglets and can lead to high economic losses in rearing. In the published first part of the study, we found EDEC in 37.4% of all investigated farms keeping weaned piglets in Germany [1]. In this part of the project, we analyzed risk factors for the presence of EDEC on those farms by using an interview-based questionnaire. During the interview, data on farm structure and performance, health status of weaned piglets, farm management as well as feeding and water supply were collected from the farm managers. Univariable analyses using either cross tabulation and a 2-sided Fisher´s exact test (FET) or a one-way analysis of variance (ANOVA) identified factors potentially associated with farm-level EDEC presence. Multivariable logistic regression models (outcome: farm positive for EDEC) as well as negative binomial regression models (outcome: number of pens per farm positive for EDEC) were used to identify final risk factors. Higher age of piglets at the beginning of pre-starter feeding (in the farrowing area) increased the EDEC risk. Significantly, the risk increased for those farms that did not provide a pre-starter to the piglets until after day ten of life (odds ratio 4.64; p-value 0.015). The use of certain vaccines (STEC, Lawsonia intracellularis and Clostridium spp.) also yielded significant results. Farms with higher weaning weights and higher weights at the end of the flat deck period had a higher risk of EDEC presence, whereas the results in relation to weaning age were inconclusive. Many variables that are considered risk factors for ED have already been excluded due to lack of significance after univariable analysis. Nevertheless, early feeding of a pre-starter in the farrowing area seems to reduce the risk of detecting EDEC in weaned piglets, as well as it seems beneficial for farms to vaccinate sows against Clostridium spp. Our study also showed a higher risk of EDEC detection for farms with superior performance/ high piglet weights. The influence of the weaning age may be the subject of further investigations.