Applied and Environmental Microbiology
Pengbo Liu, Yvonne Yuen, Hui-Mien Hsiao, Lee-Ann Jaykus, and Christine Moe

Disinfection is an essential measure for interrupting human norovirus (HuNoV) transmission, but it is difficult to evaluate the efficacy of disinfectants due to the absence of a practicable cell culture system for these viruses. The purpose of this study was to screen sodium hypochlorite and ethanol for efficacy against Norwalk virus (NV) and expand the studies to evaluate the efficacy of antibacterial liquid soap and alcohol-based hand sanitizer for the inactivation of NV on human fingerpads. Samples were tested by RT-qPCR both with and without a prior RNase treatment. In suspension assay, sodium hypochlorite concentrations ≥160 ppm effectively eliminated RT-qPCR detection signal, while ethanol, regardless of concentration, was relatively ineffective, giving at most a 0.5 log10 reduction in genomic copies of NV cDNA. Using the ASTM standard fingerpad method and a modification thereof (with rubbing), we observed the greatest reduction in genomic copies of NV cDNA with the antibacterial liquid soap treatment (0.67-1.20 log10 reduction) and water rinse only (0.58-1.38 log10 reduction). The alcohol-based hand sanitizer was relatively ineffective, reducing the genomic copies of NV cDNA by only 0.14-0.34 log10 compared to baseline. Although the concentrations of genomic copies of NV cDNA were consistently lower on fingerpad eluates pre-treated with RNase compared to those without prior RNase treatment, these differences were not statistically significant. Despite the promise of alcohol-based sanitizers for the control of pathogen transmission, they may be relatively ineffective against the HuNoV, reinforcing the need to develop and evaluate new products against this important group of viruses.