Manure treatment and natural inactivation of porcine epidemic diarrhea virus in soils

Authors: STEVENS, ERIN - University Of Nebraska; SCHMIDT, AMY - University Of Nebraska; Miller, Daniel; LOY, JOHN - University Of Nebraska; Jin, Virginia

Submitted to: Waste to Worth Conference
Publication Type: Proceedings
Publication Acceptance Date: 1/5/2017
Publication Date: 5/16/2017
Citation: Stevens, E., Schmidt, A., Miller, D.N., Loy, J., Jin, V.L. 2017. Manure treatment and natural inactivation of porcine epidemic diarrhea virus in soils. Waste to Worth Conference. Manure Treatment and Natural Inactivation of Porcine Epidemic Diarrhea Virus in Soils.

Interpretive Summary: The porcine epidemic diarrhea virus (PEDv) outbreak in North America substantially impacted swine production in recent years. Although strictly limited to swine, it is easily transmitted to suckling piglets where it causes nearly 100% mortality. Because manure may remain a source of reinfection, proper management practices to limit outbreaks need to be developed and evaluated. Human biosolids are often treated with lime to kill pathogens; therefore a series of incubation were initiated to examine how lime could be used to control PEDv in swine manure. Lime source (ag lime vs. quick lime), various incubation times in manure slurry, and a soil incubation trial mimicking the climate in three US regions was conducted to simulate current manure application practices and their effect on PEDv survival. PEDv persistence was monitored by RNA extraction followed by quantitative rtPCR and was complemented with live swine bioassays for infectivity. Results indicate that quick lime addition to modestly increase manure slurry pH (above 8.5) quickly inactivates virus and would be an excellent management tool to limit PEDv re-infection. However, enhanced ammonia losses from the manure would be expected.

Technical Abstract: The outbreak of porcine epidemic diarrhea virus (PEDv) in North America has substantially impacted U.S. swine production in recent years. The virus it is easily transmitted among pigs and causes nearly 100% mortality in pre-weaned piglets. Because PEDv is an enteric virus spread via fecal-oral contact, there is concern that stored manure may remain a source of reinfection, so proper manure management practices to limit outbreaks need to be developed and evaluated. Lime addition to human biosolids is an accepted treatment to kill pathogens; therefore, a series of incubation studies were initiated to examine the feasibility of using lime for control of PEDv in swine manure. Studies examining lime source (ag lime vs. quick lime) and incubation time in manure slurry (0 to 24 h) were conducted. In addition, a soil incubation trial mimicking the climates in three U.S. regions was conducted to simulate current manure application practices and their effect on PEDv survival in manure-amended soil. PEDv persistence was monitored by RNA extraction followed by quantitative RT-qPCR and was complemented with live swine bioassays for verifying infectivity. Results indicate that quick lime addition to modestly increase manure slurry pH (above 8.5) quickly inactivates virus and would be an excellent management tool to limit PEDv re-infection. However, enhanced ammonia losses from the manure would be expected. Immediately following application of PEDv-positive manure (limed or unlimed) to soil, the concentration of PEDv decreased immediately to a non-detectable level. These results indicate that manure-amended soil with pH 6.9 or greater is not a vector for transmission of the PED virus.