BOSTON (CBS) – It’s been a rough cold and flu season so far and now hospitals are being flooded with patients suffering a severe stomach bug.

In the MetroWest area, hundreds have visited emergency rooms over the past few weeks.

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Doctors say the norovirus, a highly contagious stomach flu is to blame.

Health officials say once it starts, it’s very difficult to contain.

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WBZ-TV’s Ken MacLeod reports

To avoid transmission at Marlborough Hospital, employees frequently scrub down door handles and other surfaces.

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Doctors say the best defense is to wash your hands on a regular basis. Hand sanitizer does not typically defend against the norovirus.