Enhanced inactivation of avian influenza virus at -20°C by disinfectants supplemented with calcium chloride or other antifreeze agents.

Avian influenza outbreaks have occurred during winter months, and effective disinfection of poultry premises at freezing temperatures is needed. The commercial disinfectants Virkon and Accel, supplemented with an antifreeze agent [propylene glycol (PG), methanol (MeOH), or calcium chloride (CaCl₂)], were evaluated for their effectiveness in killing avian influenza virus (AIV) at -20°C or 21°C. An AIV suspension was applied to stainless steel disks, air-dried, and covered with a disinfectant or antifreeze agent for 5 to 30 min. Virkon (2%) and Accel (6.25%) with 30% PG, 20% MeOH, or 20% CaCl₂ inactivated 6 log₁₀ AIV within 5 min at -20°C and 21°C. At these temperatures PG and MeOH alone did not kill AIV, but the 20% CaCl₂ solution alone inactivated 5 log10 AIV within 10 min. The results suggested that CaCl₂ is potentially useful to enhance the effectiveness of disinfection of poultry facilities after outbreaks of AIV infection in warm and cold seasons.