Introduction
African Swine Fever Virus (ASF) is a highly contagious pathogen causing
hemorrhages and higher fevers with mortality rates that approach 100%
(Ge et al., 2018). The recent fast spread of ASF across Russia, China,
and Eastern Europe has heightened awareness of ASF and other World
Health Organization reportable diseases as a threat to the United States
(US) pork production (Dee et al., 2018; Guinat et al., 2016). An
introduction in the US of Foot and Mouth Disease (FMD) or Classical
Swine Fever (CSF) have a projected loss of $2.6-$14 billion (Dee et
a., 2018; Paarlberg et al., 2009; Paarlberg et al., 2002). ASF
introduction estimates to cause the US pork industry $15 billion
revenue loss in the first two years and up to $50 billion over ten
years (Carriquiry et al., 2020). Quick and effective methods for disease
containment and elimination is a must to keep the financial burden of a
new introduction of a Foreign Animal Disease (FAD) in the country to a
minimum.
A diagnosis of a FAD like ASF in the US will evoke “stamping out
policy” by which the goal is to eliminate an outbreak by the
depopulation of all confirmed and exposed herds (World Organization for
Animal Health, 2019). A successful depopulation to eradicate disease
requires a means of disposing of infected carcasses in a manner that
properly eliminates the virus to prevent further pathogen spread and
exposure. FAD breaks in countries like the United Kingdom with FMD have
shown the limitations of current carcass disposal methods (Wilkinson,
2007). An on-farm mass burial has legislative restrictions due to
groundwater levels, burning presents public perception and human safety
concerns, and the use of rendering facilities and landfills is
troublesome due to the requirement of transporting infectious carcasses
off-site (Scudamore et al., 2002; Wilkinson, 2007). Composting, however,
is recognized as an environmentally friendly mortality management option
for routine and emergency use in Australia, New Zealand, the US, and
Canada (Guan et al., 2010; Wilkinson, 2007).
Studies on the degradation of swine viruses in compost material are
limited, even for common industry viruses such as Porcine Reproductive
and Respiratory Syndrome Virus (PRRSV) and Porcine Epidemic Diarrhea
Virus (PEDV). Traditional composting of covering full carcasses in a
carbon source is commonplace for regular daily mortality. However, the
method of grinding of carcasses (pre-processing) with carbon sources
before windrow formation may be better suited for mass depopulation.
Pre-processing requires less land space to complete than traditional
compost. Pre-processing also shows a faster completion in the composting
process than full carcasses with cattle, but limited information is
available for swine (Erickson et al., 2004). Many compost studies are
also done in temperature-controlled containers or buildings and not in
the outdoor setting that mass composting would likely occur (Guan et
al., 2010; Vitosh-Sillman et al., 2017). The ability to compost outdoors
and achieve the required high composting temperatures are of particular
concern in cold weather situations that exist during winter in the
Midwestern US, where the majority of the countries pork production
exists (Oppedahl, 2020). The risk of environmental contamination and the
spread of viruses is a concern for carcass disposal in FAD eradication
events for which little information is available for swine viral
pathogens. Thus the objectives of this study were to analyze
environmental contamination risk of pre-processing of swine carcasses,
ensure required temperatures to kill FAD swine pathogens in compost
under cold weather conditions, and to monitor the ability of compost to
denature common swine viruses.