Evaluation of changes induced by temperature, contact time, and surface in the efficacies of disinfectants against avian influenza virus.

Avian influenza viruses (AIV) are highly susceptible to all disinfectants because they are enveloped viruses. Disinfectants effective against AIV have optimum efficacies at temperatures above 20°C. Very few studies on effective disinfectants at low temperatures have been done. Disinfectants were investigated at 4 different temperatures (25, 4, 0, and -10°C) and 2 contact times (1 and 5 min) with suspension tests. Virucidal activity of the disinfectants was evaluated by carrier tests (wood and stainless steel) at 25 and -10°C. The concentration of each disinfectant for efficient disinfection within a short time (<1 min) at 25 and -10°C was also reestablished. The results from the suspension test indicated that low temperatures inhibited the virucidal efficacy of citric acid (CA) and CA + quaternary ammonium compounds (CA+ QAC) for 1 and 5 min, whereas the remaining disinfectants were effective, regardless of the short contact times and low temperatures. The carrier test results suggested that dried virus on wood was more difficult to inactivate compared with that on stainless steel. However, sodium dichloroisocyanurate and glutaraldehyde could inactivate AIV on both wood and stainless steel at -10°C. Citric acid-based agents could not sufficiently inactivate AIV at -10°C; however, the limitation due to low temperatures was overcome by adjusting disinfectant concentration. For a successful disinfection during winter, the disinfectants that could have short contact times with optimum efficacy against the target organism should be selected.