New York City's Health Department announced yesterday that cases of stomach flu have spiked in recent weeks. A significant jump to 500 emergency room visits for vomiting and diarrhea a day has occurred since November, when there were about 300 such visits daily.

“The best way to stop the spread of norovirus is to wash your hands regularly with soap and stay home from work or school if you are sick,” said Dr. Sharon Balter, Director of gastrointestinal disease for the Health Department’s Bureau of Communicable Disease. “Norovirus is common at this time of year and is not serious for most people, but it is important to take these steps to keep others from getting sick.”

New Yorkers are advised to stay home when they're sick and wash their hands frequently. People with diarrhea or vomiting should drink plenty of fluids to prevent dehydration. If dehydration symptoms are present, such as lack of urination, specialized medical care is required.

The Norovirus genus is responsible for about 50 percent of all gastroenteritis (stomach pain, diarrhea, and vomiting) around the world. The disease caused is called viral gastroenteritis, acute non-bacterial gastroenteritis or stomach flu.

Norovirus causes acute gastroenteritis that develops between 24 and 48 hours after exposure to the virus. Last month, the City of Nokia in Finland was plagued by the norovirus and other viruses and bacteria. An unauthorized valve connected by mistake the drinking water with the sewage water. This caused thousands to get sick because of the contamination, mostly by the stomach flu virus.