RALEIGH — A new strain of norovirus could make this a busy year for the nasty intestinal disease.
Seven outbreaks have been confirmed across North Carolina so far in 2013, including in Wake County, and state health officials are trying to prevent more, said Dr. Zack Moore, a medical epidemiologist for the state health department. Norovirus is a group of viruses that typically cause severe diarrhea, vomiting and stomach pain, most commonly in winter months.
“The emphasis is on working with local health departments and making sure it’s stopped,” Moore said. “Most of our outbreaks are in old folks’ homes, and we’ve unfortunately had quite a bit of experience in stopping it in those settings.”
Years with new strains tend to have the highest numbers of cases because virtually no one has immunity, said Ralph Baric, a professor of epidemiology at the Gillings School of Global Public Health at UNC-Chapel Hill. The new strain this season is called Sydney 2012, because it is thought to have originated in Australia, he said.
“Every three or four years or so, a new global pandemic strain emerges,” Baric said. “… If a virus infects virtually everyone on the planet, then virtually everyone is immune to it. The only way a virus can persist is if it changes itself so that protective immunity can no longer recognize it.”
Noroviruses are most frequently transmitted through fecal contamination in food or water, person-to-person contact and contaminated surfaces, Moore said. The best way to keep from getting sick is to carefully wash your hands, especially after using the bathroom. Alcohol-based hand sanitizers do not kill the virus, he said.
Noroviruses are more contagious than most viruses. People shed millions of the virus particles in their stool and vomit, Moore said, but it only takes between 10 and 100 particles to infect someone.
“It’s such a common infection because it’s very hardy. It can live on surfaces in the environment if it gets onto them, and the usual types of disinfectants aren’t effective against it,” Moore said. “If there are areas that have been contaminated, you have to use a dilute bleach solution to kill the norovirus.”
Wake County has had two outbreaks since Jan. 1, said county Public Health Director Sue Lynn Ledford. She said this season might have had a slight increase, but nothing out of the ordinary. Both outbreaks have been in elderly care facilities.
“That’s one of the common places we see them, because there’s a lot of dealing with human body fluids,” Ledford said. “We’ve had a very good response from (the infected facilities). They are doing extremely well and called us promptly.”
The disease is common anywhere people are in close contact with one another, which can be problematic since norovirus is most dangerous to young children and the elderly. While norovirus will make the average person sick for a day or two, Baric said, symptoms can last as long as 10 days in an elderly person.
People who have symptoms of norovirus should isolate themselves and should not go to school or work, Moore said. Infected people can spread the virus for three days after symptoms stop, he said.