The area is experiencing a surge in an extremely contagious stomach flu, called norovirus, including a new strain that comes with the usual symptoms of nausea, vomiting and diarrhea.
Norovirus often strikes annually in late February and early March, so city health officials say they aren't surprised that hospital visits by people with norovirus-like symptoms are up.
In December, for example, Boston emergency rooms were getting about 26 patients a day complaining of stomach flu, according to the Boston Public Health Commission; in the first two weeks of February, that number had increased to 45 patients daily.
There have also been institutional outbreaks of the illness at Emmanuel College, Simmons College and a facility run by Boston Health Care for the Homeless, commission officials said. In addition, about a dozen Fitchburg State College students were sent to a nearby hospital earlier this week after coming down with what is believed to be norovirus.
There is one notable difference in this year's norovirus activity in the Boston region: Specimens of the virus from one of its institutional clusters were sent for testing to the Centers for Disease Control in Atlanta, "and they have identified that we have a new variant of norovirus circulating," said Dr. Anita Barry, director of the commission's Infectious Disease Bureau.
Barry said the emergence of a new strain means that more people than usual are getting sick. Catching norovirus can sometimes provide immunity from contracting the same strain again, but when a new variant appears most people don't have that natural protection, she said.
While the virus is showing elevated activity in Boston, it does seem to be waning, Barry added.
Norovirus is typically transmitted person-to-person through stool or vomit and its symptoms usually last 24 to 48 hours. The best ways to limit the spread of the illness are to wash your hands before eating and preparing food, after using the bathroom and after changing a child's diaper.
"The unfortunate thing about norovirus is it takes very little of it for someone to get sick," Barry said, "so it's pretty easily transmitted unless you are really scrupulous about hygiene."
There are no medicines that can treat norovirus or shorten the infection's duration, so people sickened with the illness are typically advised simply to drink plenty of fluids and get extra rest.
Health officials recommend that food workers who contract norovirus stay out of work for three days after their gastrointestinal distress disappears, since the illness can still be contagious three days after symptoms subside.
This program aired on March 2, 2010. The audio for this program is not available.