Update May 24: The number of individuals reported ill from norovirus in Yolo County continues to rise. In a news release issued today, the county reported that 3,374 have been affected since May 1. Dr. Ron Chapman, the county’s public health officer, said a total of 74 cases have been reported at UC Davis. Two elementary schools in Woodland will close for one day on Friday to extend this Memorial Day long weekend in an effort to break the transmission of the illness.

Update May 12: The Yolo County Health and Human Services Agency reported in a news release that the number of people sickened by the outbreak of a gastrointestinal illness in the county is increasing "at a very alarming rate."  It also confirmed the illness as the highly contagious norovirus. A total of thirty-two cases at UC Davis are among 952 reported at 32 county schools since April 27. Mollie Teng, infection control chair and a primary care physician at Student Health and Counseling Services on campus, said that after the two confirmed cases at UC Davis, the public health department discontinued testing and now presumes that all of the campus's subsequent patients with similar symptoms have norovirus.

May 10: UC Davis student health and Yolo County health authorities are re-emphasizing the need for basic health precautions as an outbreak of a gastrointestinal illness continues to spread through the county home to UC Davis.

Dr. Ron Chapman, the county’s public health officer, said there have been hundreds of cases reported in students and teachers from county schools.

At UC Davis, several students have come to Student Health and Counseling Services and reported mild symptoms in keeping with stomach flu since Friday. More have telephoned the triage nurse at the student health facility. One case of norovirus has been confirmed.

Chapman said the outbreak across the county is in keeping with norovirus — a highly contagious form of stomach flu marked by nausea, vomiting, diarrhea and stomach cramps. It can last for one to three days, and there are no antibiotics with which to treat it.

In news release issued Friday, the county said its health and Human Services Agency was investigating whether reports of stomach flu at UC Davis and elsewhere were the result of norovirus. UC Davis issued an Aggie Alert notification to the campus community the same afternoon.

As precautions, the county’s release advises area residents to practice good hand-washing, particularly after using the bathroom and before eating, and thoroughly cleaning surfaces following guidelines of the U.S. Centers for Disease Control and Prevention.

Dean Blumberg, associate professor and chief of pediatric infectious diseases for UC Davis Health, said that alcohol-based hand gels may not work well against norovirus transmission. He emphasized the importance of washing hands with soap and water. 

"You need to wash for at least 30 seconds," Blumberg said. "Don't cut corners when washing your hands!"

Dr. Cindy Schorzman, medical director of student health services at UC Davis, said students with symptoms are being advised to:

• Stay home until symptoms are gone for 48 hours. 
• Drink plenty of fluids.
• Seek immediate medical care If symptoms worsen such that they become weak or unable to drink fluids.

Chapman said staying home 48 hours after symptoms are gone is key to halting the outbreak because the virus continues to replicate in the body even after symptoms end.

Blumberg of UC Davis Health said the major complication of norovirus infection is that it increases risk of dehydration.