THE OUTBREAK OF PORCINE EPIDEMIC DIARRHEA IN TAIWAN

Abstract

Between January 20 and April 30 of 2014, a total of 103 diarrhea cases from 47 herds in 13 counties were submitted to the Animal Health Research Institute. In 20 of the 25 herds with detail history, severe diarrhea and vomiting occurred in pigs of all ages, with mortality approaching 100% in suckling pigs. The differential etiologies, including transmissible gastroenteritis virus (TGEV), porcine epidemic diarrhea virus (PEDV), and porcine group A rotavirus (GARV), were tested by reverse transcription polymerase chain reaction (RT-PCR). The RT-PCR of PEDV was positive in 79 cases of 34 herds. Attempts to isolate PEDV in Vero cells revealed that only 7 specimens from 7 herds showed the cytopathic effects (CPEs) of fusion and syncytia. These CPEs were indeed caused by PEDV, as confirmed by RT-PCR, sequencing, and electron microscopy. Sequence comparisons of diarrhea samples and isolated PEDV were assayed by MEGA 5.2 software. The newly isolated PEDV/Taiwan/2014 strains were clustered in group 2 as novel PEDV, together with strains PEDV/USA/2013, PEDV/China/2011–2013, PEDV/Thailand/2007–2008, and PEDV/Korea/2008–2009, whereas the classical CV777 strain was placed in a separate group 1. These results indicated that a novel PEDV was the cause of the recent new outbreak of diarrhea in Taiwan.