The Efficacy of Disinfection on Modified Vaccinia Ankara and African Swine Fever Virus in Various Forest Soil Types

African swine fever (ASF) has become a global threat to the pig industry and wild suids. Within Europe, including Germany, affected wild boar populations play a major role. Fencing and carcass removal in combination with the reduction in environmental contamination are key to control further spread. The handling of the ASF virus (ASFV) is restricted to high-containment conditions in Germany. According to the regulation of the German Veterinarian Society (DVG), modified vaccinia Ankara virus (MVAV) is the virus of choice to determine the efficacy of disinfection for enveloped viruses. The aim of this study was to use the MVAV as a guide to select the best possible disinfectant solution and concentration for the inactivation of ASFV in soil. Both viruses were tested simultaneously. In this study, two layers (top and mineral soil) of soil types from six different locations in Saxony, Germany, were collected. The tenacity of ASFV and MVAV were tested at various time points (0.5 to 72 h). The capabilities of different concentrations of peracetic acid and citric acid (approx. 0.1 to 2%) to inactivate the viruses in the selected soil types with spiked high protein load were examined under appropriate containment conditions. Around 2-3 Log(10) (TCID50) levels of reduction in the infectivity of both ASFV and MVAV were observed in all soil types starting after two hours. For MVAV, a 4 Log(10) loss was recorded after 72 h. A total of 0.1% of peracetic acid (5 L/m(2)) was sufficient to inactivate the viruses. A 4 log(10) reduction in the infectivity of MVAV was noticed by applying 1% citric acid, while a 2 log(10) decline was recorded with ASFV. In conclusion, comparing MVAV to ASFV for efficacy screening of disinfectant solutions has revealed many similarities. Peracetic acid reduced the infectivity of both viruses independently of the soil type and the existence of a high organic soiling.

Automated summary

African swine fever poses a global threat to the pig industry and wild suids, with affected wild boar populations in Germany playing a significant role. The study found that MVAV can be used as a guide to select the best disinfectant concentration, with 0.1% peracetic acid effectively inactivating ASFV.