WOOSTER, Ohio -- Two recent outbreaks of norovirus in Granville in central Ohio -- on top of other outbreaks across the country -- have Ohio State University food safety experts warning people to take precautions to prevent the spread of the foodborne illness.
Norovirus is the leading cause of foodborne disease in the United States, responsible for 58 percent of all cases -- nearly 5.5 million illnesses a year. Most cases are relatively mild, but norovirus causes 26 percent (or 15,000) of all foodborne illness-related hospitalizations and 11 percent (or 149) of foodborne illness-related deaths in the United States each year. (For more, see the Centers for Disease Control and Prevention web page at http://www.cdc.gov/foodborneburden/2011-foodborne-estimates.html.)
Qiuhong Wang, research scientist and adjunct assistant professor in the Food Animal Health Research Program (FAHRP) in Wooster, is part of a team studying the stability of noroviruses on leafy greens and their potential modes of transmission to humans. Other team members are Linda Saif, distinguished university professor, Malak Esseili and Zhenwen Zhang, all with FAHRP at the Ohio Agricultural Research and Development Center, the research arm of Ohio State's College of Food, Agricultural, and Environmental Sciences.
The virus is extremely stable, especially in winter months, Wang says. It can survive on surfaces or foods even after standard disinfection procedures are instituted, and the infectious dose is low, with as few as 18-1,000 viral particles able to cause infection.
To lessen the chance of illness from norovirus, Wang advises:
- Wash hands thoroughly. This is important not only to prevent foodborne illness, but also to decrease the risk of person-to-person transmission, which can occur not only during illness but for one to three weeks after an infected person's symptoms subside. Person-to-person transmission especially occurs during the winter when people are in closed settings with close contact among individuals -- this includes schools, colleges, day care centers, nursing homes, among military troops and on cruise ships. It's important to note, Wang says, that 20 percent of norovirus-infected people do not show any symptoms, but still can spread the virus to others. Most people don't wash their hands long enough -- at least 20 seconds. For guidance, see http://foodsafety.osu.edu/picture-lessons/keep-your-hands-clean/.
- Avoid raw produce. When foods are cooked, norovirus and other pathogens are killed. This could be especially important for individuals who are most at risk -- the elderly, young children, and people with cancer or who have other diseases or chronic conditions.
- When preparing leafy greens to be eaten raw, as in a salad, purchase a whole head of lettuce and rinse leaves thoroughly. The more leafy greens are processed, such as those in ready-to-eat bags, the more opportunity there is for contamination from norovirus.
Wang also is working with a team including Saif and Kwon il Jung, another research scientist with FAHRP, in collaboration with K.O. Chang of Kansas State University to try to develop antivirals to human norovirus. Using OARDC's germfree piglets, the team is testing potential new antivirals in initial trials. The team at OARDC also hopes to initiate new work in collaboration with a local Ohio company to test more effective disinfectants and hand sanitizers for norovirus.