Pierce County, Washington. Pierce County is a county in the U.S. state of Washington. As of the 2010 Census, the population was 795,225, making it the second-most populous county in Washington behind King County. The county seat and largest city is Tacoma.
You can be contagious from a few days up to two weeks or more, depending on which virus is causing your stomach flu (gastroenteritis). A number of viruses can cause gastroenteritis, including noroviruses and rotaviruses.
Most of the time, you will become contagious about  24 to 72 hours after contracting the influenza virus and remain that way for up to five days after the onset of symptoms. But children or people with compromised immune systems can be contagious to those around them for up to two weeks.