Approximately 85 students at George Washington University in Washington have been sickened by norovirus this week, according to the University's Student Health Service.

Since Monday, the virus has been found at GW's Foggy Bottom campus, Mount Vernon campus and other off-campus locations.

Norovirus is a gastrointestinal illness commonly found on cruise ships. It causes severe inflammation of the stomach and intestines. Also known as stomach flu, viral gastroenteritis and food poisoning, it is highly contagious, passed person to person through direct contact by food, drink or contaminated surfaces.

Symptoms include diarrhea, vomiting, low grade fever, muscle ache, headache, chills and stomach pain.

The DC Department of Health has been working with university to address the problem and says it's not unusual for these types of gatrointestinal viruses to occur around this time of year.

"Since January 1, 2012, DOH has investigated a total of four confirmed norovirus outbreaks [in Washington, D.C.], including the outbreak at GWU," said Najma Roberts, Public Information Officer for the DC Department of Health. "Now is typically the time of year in which the city experiences a rise in this type of illness and it can cease as quickly as it occurs. While norovirus outbreaks occur throughout the year, nationally over 80% of them occur during November to April."

According to the Centers for Disease Control and Prevention, people with the virus are contagious up to two weeks after they begin to have symptoms. Typically, most people get better within a couple of days, but this can be a serious illness for some and there is no treatment or vaccine.

The CDC estimates that there are more than 20 million cases a year. In fact, norovirus is the cause of more than half of all foodborne illness outbreaks.

The best way to prevent transmission of the virus, according to the CDC, is wash your hands thoroughly with warm soapy water; if infected, clean and disinfect possible contaminated surfaces and don't prepare food if you're sick.