CategorySwine Health - General Disease
Date Full Report Received08/31/2017
Date Abstract Report Received08/31/2017
InvestigationInstitution: Kansas State University
Primary Investigator: Dr. Megan Niederwerder
Co-Investigators: Dick Hesse
Funded ByNational Pork Board
Swine enteric coronavirus diseases (SECD), including porcine epidemic diarrhea virus (PEDV) and porcine deltacoronavirus (PDCoV), have been significant disease threats to the North American swine industry since being introduced approximately 4 years ago. This report serves to review the information gained on pathogenesis, management, transmission and risks of SECD over the last four years through research and industry experience. The spread of PEDV and PDCoV throughout major swine-producing states within weeks of being introduced underscores the susceptibility of the industry to introduction and rapid dissemination of infectious diseases. Clinical disease of these pathogens is age dependent, with neonatal pigs having the highest morbidity and mortality, and does not correlate with pathogen shedding as prolonged maintenance of the virus in clinically healthy animals is common. Long-term impacts of SECD through reduced weight gain and prolonged return to baseline production is likely an underestimated economic loss due to SECD. Transmission of SECD is primarily fecal-oral and the dose necessary for productive oral infection is extremely low; ingestion of aerosolized virus may also play a role, albeit to a lesser extent. Several factors likely contributed to the introduction and spread of SECD throughout the U.S., with contaminated feed, feed totes, transport vehicles, personnel and other fomites being identified as major risks. Disease control strategies after SECD introduction at the farm can be directed at management or eradication through controlled feedback exposure, vaccination, piglet depopulation, segregated early weaning, feed additives, and/or enhanced biosecurity. Programs designed to “Load-Close-Expose” the herd are likely the most commonly utilized management tools; however, a standardized and widely-accepted protocol for the safe and consistent administration of feedback is lacking. Mitigants of SECD such as disinfectants, medium chain fatty acids, formaldehyde, heat and radiation often inactivate the virus but maintain positive PCR values, highlighting an important distinction between infectious virus and viral RNA. A survey of swine professionals conducted for this review revealed that 1) the majority of respondents (75%) believe SECD can be eradicated from the U.S., 2) most herds have been successful at long-term elimination of SECD after exposure (80%) and 3) views on SECD do not significantly differ between swine dense and not swine-dense regions of the U.S. Overall, our current knowledge of SECD provides both opportunities and challenges for future management and potential eradication.