The North Central Public Health District says a gastrointestinal illness outbreak in The Dalles that causes vomiting and diarrhea has led to 100 absences at several local elementary schools, and 22 cases at a local long term care facility.  The district says cases started slowing down by mid-week.  The Centers for Disease Control says it is the height of norovirus season, and cases nationally are at a 12-month high.  North Central Public Health District communicable disease investigator Sirisha Botta says while these are suspected cases of norovirus, only three are confirmed locally.  It takes a laboratory sample to confirm norovirus, and that is not often done.  Norovirus symptoms usually resolve in three days, but you are contagious for several days after you recover.  She adds the best protection against the highly contagious illness, suspected to be norovirus is careful hand washing.  Those who do come down with a gastrointestinal illness should drink plenty of liquids to replace fluid loss.