(UPI) -- Current protocols for washing dishware in restaurants may not be enough to guard against the highly contagious norovirus, or stomach flu, U.S. researchers say.
"We know that when public food establishments follow the cleaning protocols, they do a very good job at getting rid of bacteria," Melvin Pascall, associate professor at Ohio State University, said in a statement. "Now we can see that the protocols are less effective at removing and killing viruses -- and this may help explain why there are still so many illnesses caused by cross-contaminated food."
Pascall and Jianrong Li, an assistant professor of virology at Ohio State, led a team to test the ability of the norovirus and common bacteria to survive food service cleaning.
The research team infused cream cheese and reduced fat milk -- two foods that are known for being difficult to clean off -- with murine norovirus, E. coli K-12 or Listeria. The scientists applied the dairy products to stainless steel utensils, ceramic plates and glassware and put the tableware through a variety of chlorine and quaternary ammonium -- such as Pine-Sol Cleaner or Fantastik All Purpose Cleaner -- sanitary protocols via commercial dishwasher or hand washing.
The study, published in PLoS One, found both the commercial dishwasher and manual washing reduced bacterial loads of E. coli K-12 and Listeria enough to meet safety standards, but neither technique was able to significantly reduce the presence of norovirus. Overall, hand washed dishes were more likely to contain traces of both bacteria and viruses than those cleaned in a commercial dishwasher, the study said.
"Even though the protocols were able to kill some of the virus, norovirus is highly contagious and it takes only a few viral particles to infect humans," Li said.