Propylene glycol maintains the virucidal efficacy of disinfectants at sub-zero temperatures: implications for African swine fever biosecurity

Abstract African swine fever (ASF) is a highly contagious viral disease that continues to threaten global pig production. In the absence of an effective vaccine, strict biosecurity and disinfection remain the primary measures limiting virus transmission. However, in temperate climates winter conditions may significantly compromise disinfection efficiency, because many liquid formulations freeze at sub-zero temperatures, preventing proper surface coverage and virus–disinfectant contact. Background : The present study evaluated the role of propylene glycol as a cryoprotective additive in disinfectant formulations used against African swine fever virus (ASFV). Selected active substances recommended for ASF control were tested in a suspension assay based on the PN-EN 14675 standard using the Ba71V strain of ASFV. Experiments were conducted at 21 °C, −10 °C and −20 °C under low and high levels of soiling conditions. Results : Preliminary experiments demonstrated that 30% propylene glycol prevented the freezing of disinfectant formulations without compromising their virucidal activity. Sodium hypochlorite, glutaraldehyde, potassium peroxymonosulfate, caustic soda and acetic acid retained strong virucidal activity across all temperatures, achieving ≥4 log 10 reductions in virus titer. In contrast, phenol, benzalkonium chloride and formaldehyde showed limited measurable activity, mainly due to cytotoxic effects or reduced performance under the tested conditions. Conclusions : These findings indicate that incorporation of propylene glycol can maintain disinfectant stability at sub-zero temperatures without compromising the efficacy of highly active compounds. Glycol-stabilized formulations may therefore improve the reliability of winter biosecurity protocols aimed at limiting ASFV transmission.