Background African swine fever (ASF) is a lethal contagious disease affecting both domestic pigs and wild boars. Even though it is a non-zoonotic disease, ASF causes economic loss in swine industries across continents. ASF control and eradication are almost impossible since effective vaccines and direct antiviral treatment are not available. The persistence of ASFV on fomites plays an important role in the indirect transmission of ASFV to pigs encountering ASFV-contaminated fomites. ASFV persistence on porous and non-porous fomites (glass, metal, rubber, and cellulose paper) at different environmental temperatures was determined. The persistence of ASFV of fomites was determined by the rate of ASFV inactivation in terms of DT, or the time required to reduce ASFV per 1 log at each selected environmental temperature (T). DT is used to compare the persistence of ASFV on the fomites. Results The mean D25, D33, and D42, of dried infectious ASFV on glass, metal, rubber, and paper were in the ranges 1.42–2.42, 0.72–1.94, and 0.07–0.23 days, respectively. The multiple DT were used to develop a DT model to predict the DT for some other environmental temperatures. The DT models to predict the persistence of dried infectious ASFV on glass, metal, rubber, and paper are log DT = (− T/21.51) + 1.34, log DT = (− T/20.42) + 1.47, log DT = (− T/14.91) + 2.03, and log DT = (− T/10.91) + 2.84, respectively. A spreadsheet as a quick and handy tool predicting the persistence time of dried infectious ASFV on fomites at various environmental temperatures based on these DT models is available for public to download. Conclusion Persistence of dried infectious ASFV on paper are significantly the longest at lower environmental temperatures whereas that of dried infectious ASFV on paper is significantly the shortest at higher environmental temperature.

The indirect transmission of the African swine fever virus (ASFV) is through contaminated fomite, feed ingredients, pork- and pig-derived products, including swill, as ASFV is highly stable within suitable organic material. Some previous studies have indicated that ASFV outbreaks were associated with swill feeding, particularly in smallholder pig farms. These outbreaks emphasize the significance of the appropriate heat treatment of swill to eliminate ASFV residual titer. The World Organization for Animal Health (OIE) recommended the heat treatment of swill at a temperature of at least 90°C for at least 60 min, with continuous stirring, while the Food and Agriculture Organization (FAO) recommended heat treatment at 70°C for 30 min. The lack of scientific evidence regarding ASFV inactivation by heat treatment of swill leads to such inconsistent recommendations. Therefore, the objectives of this study were to assess the thermal inactivation of ASFV in three swill formulae and to develop a DT model to predict DT at some other inactivation temperatures. The significant reduction of ASFV in swill occurred at temperatures as low as 60°C. DT or decimal reduction time (DRT) is defined as the time required to reduce the virus titer by 1 log, and this was also used as a comparative index of heat resistance. The mean D60, D70, D75, and D80 of ASFV in three swill formulae were in the ranges 23.21–33.47, 5.83–10.91, 2.15–2.22, and 1.36–1.47 min, respectively. These DT could be widely used for any nutritive composition of swill other than the three swill formulae in this study since there was no statistical difference of all DT of ASFV across three swill formulae. Based on D70 and the predicted D90 from the DT model in this study, including the highest ASFV titer in pork products, the calculated inactivation times at 70 and 90°C were 119 and 4 min, respectively.

African swine fever virus (ASFV) causes a fatal infectious disease affecting domestic pigs and wild boars. ASFV is highly stable and easily transmitted by consumption of contaminated swine feed and pork products. Heat treatment of feed ingredients is a means to minimize the risk of contamination through swine feed consumption. The objectives of this study were to determine the thermal inactivation of ASFV in non-animal and animal origin feed ingredients. The rate of thermal inactivation is represented by decimal reduction time (DT) or time required to reduce ASFV per 1 log at temperature T. The mean D60, D70, D80 and D85 of meat and bone meal (MBM), soybean meal (SBM), and maize grain (MZ) are in the ranges 5.11–6.78, 2.19–3.01, 0.99–2.02, and 0.16–0.99 min, respectively. DT is used to compare the heat resistance of ASFV in the feed ingredient matrices. The mean DT of ASFV in MBM, SBM and MZ was not statistically significant, and the heat resistance of ASFV in MBM, SBM, and MZ was not different at 60, 70, 80, or 85 °C. The multiple DT was used to develop a DT model to predict DT at various inactivation temperatures. The DT models for MBM, SBM, and MZ are log DT = − $$\left( {\frac{T}{32.08}} \right)$$ T 32.08  + 2.69, log DT = − $$\left( {\frac{T}{31.77}} \right)$$ T 31.77  + 2.55, and log DT = − $$\left( {\frac{T}{18.96}} \right)$$ T 18.96  + 4.01. To expand and ease the field applications, a spreadsheet predicting the DT and the inactivation time (with 95% confidence interval) from these DT models is available to download.

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