Inactivation of feline calicivirus, a surrogate of norovirus (formerly Norwalk-like viruses), by different types of alcohol in vitro and in vivo.

Hand disinfection is an important measure to prevent transmission of norovirus (formerly called Norwalk-like viruses) from hands or environmental surfaces to other objects. Therefore, three types of alcohol (ethanol, 1- and 2-propanol) were examined for their virus-inactivating properties against feline calicivirus (FCV) as a surrogate for norovirus. Tests were performed as quantitative suspension assays or as in vivo experiments with artificially contaminated fingertips. The in vitro experiments showed that 1-propanol was more effective than ethanol and 2-propanol for the inactivation of FCV: in tests with the 50 and 70% solutions of the different alcohols, a 10(4)-fold reduction was observed with 1-propanol after 30 s, whereas the other alcohols were effective only after 3 min contact time. The greatest efficacy did not occur at the highest concentrations (80%). The following concentrations (extrapolated data) showed the greatest virus-inactivating properties in the suspension test: ethanol 67%, 2-propanol 58% (exposure times of 1 min) and 1-propanol 60% (exposure time of 30 s). The results from fingertips experiments with 70 and 90% solutions and an application time of 30 s confirmed these findings: the 70% alcoholic solutions were more effective than the 90% solutions. In contrast to the suspension tests, 70% ethanol showed the greatest efficacy in vivo with a log(10) reduction factor (RF) of 3.78 compared with 70% 1-propanol (RF 3.58), 70% 2-propanol (RF 2.15) and hard water (RF 1.23). Ethanol and 1-propanol-based solutions with a high alcohol content thus appear most effective.