Inactivation rates of African swine fever virus by compound disinfectants

African swine fever is an important viral disease of domestic pigs and wild boars. Inactivation of the African swine fever virus (ASFV) contaminating equipment and premises is an effective biosecurity risk management measure to prevent the introduction of ASFV through contaminated fomites and the environment. Even though some chemical agents' virucidal activity against ASFV was previously demonstrated, compound disinfectants are still limited. For the fact that the ASFV titer in some excretions from pigs was far >4 log. Even after the application of disinfectants as instructed by the manufacturers, the excessive ASFV load in the excretions from pigs could contaminate fomites or the environment. To solve this dilemma, the concept of contact time of disinfectant for 1–log reduction was introduced, as the decimal reduction time or D value. Therefore, the objective of this study was to assess the inactivation rate of four compound disinfectants against ASFV as the D value. Four compound disinfectants (iodine and phenol, quaternary ammonium and alcohol, and two quaternary ammonium and glutaraldehyde compounds) currently used in the veterinary field were evaluated in a suspension test at 25 °C in the absence of interfering substances. Primary porcine alveolar macrophages were used to determine the titer of ASFV genotype II (strain VNUA/HY-ASF1/Vietnam/2019). The virucidal activity of four compound disinfectants achieved 4–log ASFV reduction. The mean D_0.5%, D_0.25%, and D_0.125% values of all disinfectants inactivating ASFV were 1.62–3.60, 2.60–3.8, and 2.89–3.90 min, respectively. The D value of disinfectants allows users to manipulate the appropriate concentration and/or contact time of the disinfectant, depending on the magnitude of ASFV contamination, to completely inactivate the ASFV titer on the fomites to minimise a potential biosecurity risk.