PSI-7 Prevalence and distribution of Senecavirus A in United States swine feed mills

Abstract

Abstract There is limited information about Senecavirus A (SVA) transmission in the feed supply chain. The objective of this experiment was to determine the prevalence and distribution of SVA in U.S. swine feed mills. A total of 375 samples were collected from 11 surfaces + one feed sample collected from 11 different feed mills in 8 different states. Due to the seasonality associated with pathogenic hazards, the same locations in feed mills were swabbed in Late Fall 2016, Winter 2016/17, and Summer 2017. Surfaces were swabbed according to the Centers for Disease Control protocols for collecting environmental samples using pre-moistened environmental swabs in 5 mL of neutralizing broth. Detection of SVA was performed via RT-PCR and reported in Cycle threshold (Ct). Data were analyzed using the freq procedure of SAS, with chi-square test to determine the prevalence of SVA within season or distribution among feed mill locations. Notably, no mills were manufacturing feed for SVA-positive herds at the time of analysis. Five of 375 samples analyzed positive for SVA, with Ct ranging from 37.4 to 39.9. There was a tendency (P = 0.069) for SVA prevalence to be greater in winter than late fall or summer. There was no detected impact (P = 0.409) of SVA distribution varying across location within feed mill. A sow farm being fed by the mill with SVA on worker shoes was subsequently diagnosed with SVA after the sample as collected. These results indicate that SVA was not widespread throughout the swine feed mills analyzed in this experiment. However, we are unaware of any other studies evaluating presence in feed mills. Little is known about SVV transmission, but the clinically affected farm fed out of the mill with SVV presence suggest further investigation, as feed or feed delivery may be a route of entry into farms.