Since May 1, the norovirus outbreak in Yolo County in northern California has topped the 4,000 case mark as of Wednesday.


The Yolo County Health & Human Services Agency puts the case count at 4,001. The outbreak prompted the closure of several county schools just prior to the Memorial Day weekend.

Suspect norovirus cases have been reported in Santa Barbara, Santa Clara and Sacramento Counties.

The Centers for Disease Control and Prevention (CDC) estimates that there are between 19-21 million cases of norovirus illness each year in the U.S. Additionally, CDC estimates that norovirus contributes to 56,000-71,000 hospitalizations and 570-800 deaths each year in the U.S.

The spread of Norovirus can be prevented by practicing proper hand hygiene. Important strategies include washing hands with soap and water, especially after using the toilet and changing diapers, and always before eating and preparing or handling food.

Symptoms of Norovirus include fever, nausea, vomiting, diarrhea and stomach pain. Symptoms last for 1-3 days. However, after symptoms go away, people are still highly infectious, especially the first 48 hours. There is no treatment for Norovirus. The most important steps to prevent the spread of Norovirus is to stay home if you are sick, and for another 48 hours after symptoms go away, and to regularly wash hands.