Impact of a porcine epidemic diarrhea outbreak on swine productivity in Japan: a retrospective cohort study

YAMANE, Itsuro; YAMAZAKI, Hisanori; ISHIZEKI, Sayoko; WATANABE, Yugo; OKUMURA, Hanako; OKUBO, Mitsuharu; KURE, Katsumasa; HAYAKAWA, Yuiko; FURUKAWA, Makoto; OOI, Munetaka; MIZUKAMI, Yoshihiro; ITO, Mitsugu

In the 38 PED-positive herds, PED was diagnosed in 23 herds in April, in 14 herds in May and in one herd in June. The median PED period was 43.5 days (range, 13 to >90 days). During the PED epidemic, clinical signs were identified in farrowing barns (36 herds, 94.7%), nursery barns (25 herds, 65.8%), finishing barns (23 herds, 60.5%) and pregnant sow barns (29 herds, 76.3%). The means and confidence intervals (CI) for AFI in the PED-negative, S-PED-positive and L-PED-positive herds were 580 (95% CI, 378-782), 464 (95% CI, 234-695) and 1,259 (95% CI, 620-1897), respectively, and the L-PED-positive herds had significantly higher AFI than the PED-negative herds (P<0.05). In the repeated-measure analysis, the time factor and the interaction between time and group were significant for PRWM, POWM, PWL and MP. However, only the time factor was significant for PBA and LMFY. The expression as "time factor was significant" means average values of all 3 groups differ significantly among different time points. For example, the average preweaning mortality was significantly higher in April-June 2014 than at other time points.