SHIC-Funded Research Questions Feed Role in PDCoV Outbreaks

March 9, 2022 — Paul Sundberg

In research funded by the Swine Health Information Center (SHIC) and conducted at Kansas State University, two feed mills and three breed-to-wean facilities diagnosed with porcine deltacoronavirus (PDCoV) were investigated for possible connections related to the outbreak. Initial suspicion was feed manufacture and delivery processes were involved in disease transmission. Goals of the research were to understand if the feed mill was the origin of disease and then determine if trucks or people, either coming from the infected farms or coming from the feed mills, served as vectors to spread this virus.

Both feed mills were audited and environmental samples collected in areas deemed high risk for virus contamination. All breed-to-wean facilities had PDCoV detected as would be expected, while the only positive samples for enteric coronaviruses associated with feed mills were feed delivery trucks.

This diagnostic investigation did not find evidence within the feed supply chain indicating feed or feed delivery was associated with outbreaks of PDCoV. Due to the nature of timing, it is believed that the contamination identified at the infected sites was due to the intentional exposure through controlled oral exposure. Furthermore, it is not known what the specific mechanism of transmission was to these farms, although other routes must be considered such as personnel and other possible fomites such as incoming supplies. The goal of this investigation was to evaluate the likelihood of a link between feed manufacturing and delivery with the outbreak of clinical disease, so greater investigation into potential routes of entry were not explored.

This investigation highlights the importance of biosecurity during controlled oral exposure because viral contamination can be detected outside of the farm perimeter and common events such as feed delivery may serve as a mechanism for transfer of viral contamination back to the feed mill or to other farms. The current investigation emphasizes the importance of biosecurity in the feed supply chain at both the feed manufacturing and delivery stages, with particular focus needing to be directed towards personnel movement.

SHIC, launched by the National Pork Board in 2015 solely with Pork Checkoff funding, continues to focus efforts on prevention, preparedness, and response to novel and emerging swine disease for the benefit of US swine health. As a conduit of information and research, SHIC encourages sharing of its publications and research. Forward, reprint, and quote SHIC material freely. SHIC is funded by America's pork producers to fulfill its mission to protect and enhance the health of the US swine herd. For more information, visit http://www.swinehealth.org or contact Dr. Sundberg at psundberg@swinehealth.org.

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Paul Sundberg, Executive Director, Swine Health Information Center