Norovirus decontamination methods.


Date: Thu 13 Jun 2002
From: Paul Webber

An Alternative to Chlorine-based Biocides
The request for information from Dr. Wheeler [see: " Norwalk-like virus, decontamination: RFI 20020612.4475"] was forwarded to me for my opinion. The moderator requested a possible alternative to chlorine-based biocides to battle Norwalk virus and Norwalk-like viruses (NLV). Undoubtedly, chlorine bleach (NaHCl) at 5000 - 10 000 ppm will have a cidal affect on the pathogen but is, as is noted, very harmful to surfaces, equipment and users. Perhaps the concern for worker safety would even eclipse the sanitizing effects.

A Canadian-made and widely accepted possible alternative is Accelerated Hydrogen Peroxide (AHP). Several disinfectant products, including a high-level disinfectant, have been created with this remarkable (my opinion) technology. Developed and manufactured by Virox Technologies Inc () of Toronto, AHP has documented cidal affects against non-enveloped viruses. AHP disinfectants were tested against Poliovirus type 1 (Sabin) with standard organic and hard water challenges, and were found to reduce the pathogen by almost 99.999 percent with a 5-minute contact time. Documented evidence against poliovirus allows manufacturers to claim efficacy against all non-enveloped viruses, including Norwalk virus and NLV.

Further, the manufactures have shown that the in-use dilution of the disinfectant that employs AHP technology is safe on all colour-stabilized fabrics (including carpet, drapery, air filters, etc.) and most metals. Some soft metals, when left to soak for a longer period of time, exhibit corrosion. The product is marketed as safe for contact with skin, eyes, respiratory and digestive systems, and has no noticeable odour or colour additives.

I put forward that this may be an acceptable alternative to chlorine-based biocides. To my knowledge is it as yet unavailable in the United States, but widely distributed and used in Canada and other nations.

Date: Mon 17 Jun 2002
From: Marc-Alain Widdowson

Another Thought on Norwalk-like Virus Decontamination

There is a real gap in knowledge of which disinfectants (apart from very high concentrations of sodium hypochlorite (bleach) solution) can be used to decontaminate the environment in protracted "person-to-person" outbreaks of Norwalk-like viruses so often a problem in cruise ships.

A recent paper (2001) in the Journal of Food Protection (Gulati et al: 4 (9) 1430-4) uses feline calicivirus as a model for Norwalk-like viruses. The evidence presented suggests that phenolic compounds at concentrations of twice the manufacturer's recommendations (which are 1:256 dilution of 4.25 percent o-benzyl p-chlorophenol and 4.75% o-phenylphenol) might be the most effective disinfectant against Norwalk-like viruses. This compares with sodium hypochlorite, which even at concentrations of 800 ppm was not particularly effective.

I don't, however, know the effects of phenolics on soft furnishings.