Comparative efficacy of ethanol and isopropanol against feline calicivirus, a norovirus surrogate

Background: Improper disinfection of environmental surfaces contaminated by the feces or vomitus of infected patients is believed to be a major cause of the spread of noroviruses (NoV) in close institutional settings. Although several disinfectants are available. the search for safe and effective disinfectant continues. Because alcohol and alcohol-based products have been used as antiseptics and their efficacy against several enveloped viruses has been documented, we wanted to determine their efficacy against nonenveloped calicivirus. Methods: Feline calicivirus (FCV) was used as a surrogate for NoVs, using the carrier test. We evaluated the virucidal efficacy of various concentrations of ethanol and isopropanol against FCV, dried on an inanimate, nonporous contact surface for contact times of 1. 3. and 10 minutes. The virus was eluted after alcohol treatment and titrated in feline kidney cells. Percentage virus inactivation was calculated by comparing these titers with those obtained with virus eluted from controls. Results: Ethanol at 70% and 90% and isopropanol at 40% to 60% concentrations were found to be the most effective, killing 99% of FCV within a short contact time of I minute. Conclusion: Isopropanol was more efficacious than ethanol at 40% to 60% concentrations, suggesting that the use of an appropriate concentration of isopropanol or ethanol would help in controlling the transmission of NoVs from environmental contact surfaces.