PATHOLOGICAL OUTCOMES DURING AN OUTBREAK OF ENCEPHALOMIOCARDITIS VIRUS INFECTION IN A PIG FATTENING UNIT

Introduction: Encephalomyocarditis virus (EMCV) is a Cardiovirus with a worldwide distribution and a broad host range. Although rodents are considered the major virus reservoir, pigs are the domestic species most susceptible to the infection, with acute myocarditis in piglets and reproductive disorders in sows. Materials and Methods: An outbreak characterized by sudden mortality of pigs of 30 kg/BW (80 animals died) in a fattening herd lasting one month was observed in October 2015. Sudden death was the main clinical sign. For a few pigs trembling and anorexia were also reported. Necropsy was done on a selection of dead pigs, and bacteriological, molecular (PCR for PRRSV, EMCV, PRV) and histological investigations were performed. Results: Gross examination showed congestion, pulmonary oedema, pleural and pericardial fluid transudate. Grey-white necrotic foci were evident on myocardium and epicardium. Histology showed myocardial focal areas of necrosis, calcification and interstitial infiltrations of lymphocytes and neutrophils. In addition, hepatic haemorrhagic necrosis and pancreatic islets necrosis were observed. Only the RT-PCR for EMCV resulted positive. Conclusions: The present work describes the pathological findings associated with an outbreak of sudden mortality in pigs. The suspect of an EMCV infection, based on clinical signs and necropsy outcomes, was confirmed by histology and RT-PCR. From the onset of the first case, several relapses were observed in the farm on January, March and April 2016. The recurrence of the infection was described in a previous work. The presence of rodents can be associated with the introduction of the virus into the herd.