How long does it take a single virus to spread around a busy facility? As new research points out, disturbingly quickly.
Using tracer viruses, researchers from the University of Arizona in Tucson found that the contamination of just a single doorknob or table top can result in the rapid dissemination of viruses throughout office buildings, hotels, and healthcare facilities. After just two to four hours, the virus could be detected on 40-60% of workers and visitors to facilities and frequently touched objects.
For the study, the researchers used bacteriophage MS-2 as a surrogate for the human norovirus, the most common cause of stomach flu in the United States. Every year, noroviruses cause about 19 to 21 million illnesses, 56,000 to 71,000 hospitalizations, and nearly 800 deaths. Touching surfaces or objects contaminated with this virus — and then putting fingers in your mouth — is a common source of infection. The researchers used the MS-2 bacteriophage because it's similar to the norovirus in shape, size, and resistance to disinfectants.
During the experiment, the phage was strategically placed on one or two frequently touched surfaces at the start of the work day in office buildings, conference rooms, and healthcare facilities. Then, after specific periods (two to eight hours), the researchers sampled 60 to 100 fomites — surfaces capable of carrying infectious organisms for the phages (namely light switches, bed rails, table tops, countertops, push buttons, coffee pots handles, sink tap handles, door knobs, phones, and computer equipment).
"Within two to four hours between 40 to 60% of the fomites sampled were contaminated with virus," noted Gerba in a press release.
These results show that viral contamination of fomites in facilities occur quickly, but the researchers say a simple intervention can significantly help reduce exposure to viruses.
"Using disinfecting wipes containing quaternary ammonium compounds (QUATS) registered by EPA as effective against viruses like norovirus and flu, along with hand hygiene, reduced virus spread by 80 to 99 percent," says Gerba.
And in fact, subsequent tests during the intervention phase showed that the number of fomites on which the virus was detected was reduced by 80% or more, while the concentration of the virus was reduced by 99% or more.
It's important to note that the rate of infection among workers was not tracked (the experiment merely followed the spread of the phage around the building). What's more, the prescription — the use of disinfecting wipes — could eventually backfire by creating hardier viruses that are more resistant to such chemicals.
This research was recently presented at the 54th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC), an infectious disease meeting of the American Society for Microbiology.
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