Infectivity of swine manure from pits on sow farms at varying lengths of time post infection with porcine epidemic diarrhea virus (PEDV)

This project was designed to test manure from manure lagoons on sow farms across the midwest for the presence of viable PEDV in an effort to understand the risk of transmitting this virus during pit pumping. Of the pits we tested, we found that only one lagoon had evidence of infectious virus present, and this farm was at that time weaning PED positive piglets. These data continue to emphasize the need for proper biosecurity measures and planning during the pit pumping, especially when dealing with known PED positive sow farms.

In this study, we sampled 5 manure lagoon from barns in Iowa, Nebraska and North Dakota. At each site, manure was sampled by tossing a small bucket attached to a cord into the lagoon at three different locations. The manure samples were tested individually for PEDV at the University of Minnesota Veterinary Diagnostic lab by polymerase chain reaction (PCR) and also tested by swine bio-assay for presence of live virus.

All manure samples were positive for PED by PCR. One case also tested positive for Swine Delta Coronavirus on a herd that was co-infected with both viruses. We found that on average, lagoons had a PCR cycle time of 30, indicating a relatively high amount of viral genetic material. When tested by swine bio assay, one barn that was presently shedding PED (weaning PED positive piglest) was positive.

In the swine bio-assay, 20 mL of manure from one site was administered via a stomach tube to a single pig and was observed for 3 days. At the end of the study the pig was taken to the diagnostic laboratory and infection was confirmed by the diagnosticians there.

In conclusion, of the 5 lagoons sampled in this project, only one had evidence of viable virus. Therefore, it is recommended to continue to be very diligent regarding biosecurity and sequencing of manure pumping equipment. It is important to note, that it is possible for to have missed live PEDV in several of the lagoons simply due to issues of sample size. It is hopeful that careful planning and good communication may help minimize the spread of PEDV during future manure pumping events.