Determining the Efficacy of Disinfectants against Human Noroviruses among 20 Commercially Available Disinfectants in Korea and Japan

Introduction: Korea and Japan have seen increased norovirus outbreaks in the winter of 2012 from which multiple human deaths have been reported. The majority of transmission of norovirus occurs through environmental contamination and human-to-human contacts. Therefore, use of disinfectant can be important means to prevent transmission of norovirus. However, currently available disinfectants have been tested against either Murine norovirus and or Feline Calicivirus, both surrogates of human norovirus and therefore proper efficacy of disinfectants against human norovirus is unclear. We tested 20 commercially available disinfectants for their true efficacy against human norovirus.

Purpose: Our aim is to screen most commonly used top 20 commercial disinfectants for their true efficacy against human norovirus and report our results so that consumers are better informed about the products they are using in protection against spread of norovirus.

Methods: Using peptide sequence antigen, we produced monoclonal antibodies against two strains of norovirus, Norwalk virus (GI.1) and GII.4. The resulting two monoclonal antibodies were conjugated to magnetic beads to create immunomagnetic bead (IMS) reagent to capture human norovirus. This IMS reagent was used to capture intact norovirus after the treatment of disinfectant. The IMS method was shown to not only capture norovirus, but also effective in removing free RNA and PCR inhibitors. We tested the efficacy of varying concentrations of ethanol, sodium hypochlorite, quaternary ammonium compounds along with 20 commercially available disinfectants using IMS method followed by RT-qPCR. 

Results: The sensitivity of this procedure was approximately 100 virus particles for GI.1 and GII.4 virus, respectively. The average virus log reduction by various disinfectants was all below log 0- log 1.5 at best. However, only one product and sodium hypochlorite showed more than 4 logs of reduction against both GI.1 and GII.4. 

Significance: Our results indicate that majority of disinfectants are not effective against human norovirus. Many previous reports also showed that naked envelope viruses such as norovirus are resistant to vast types of disinfectants. Therefore, it is very important to report and inform consumers on true efficacy of various disinfectants against human norovirus, not the surrogates.