Norovirus illness often peaks in winter. The Michigan Department of Health and Human Services (MDHHS) has identified increases in norovirus activity recently and is urging Michigan residents to take precautions to stay healthy. Although several viruses can cause vomiting and diarrhea, norovirus is the most common. These viruses are easily spread through food, by person-to-person contact or through contaminated surfaces. Therefore, take caution if someone in your household is ill. Norovirus infection is sometimes described “stomach flu” but it is not related to influenza (flu), a respiratory viral illness that can cause fever, cough, chills, headache, muscle aches, runny nose and sore throat. Norovirus often causes nausea, vomiting, diarrhea and stomach cramping, but infected people may also have a low-grade fever, headache, weakness and muscle aches. Symptoms can begin as early as 12 hours after exposure to the virus or as late as 72 hours. The symptoms of norovirus usually last one to three days. In most cases, ill individuals fully recover without medical attention. However, norovirus infection may result in hospitalization due to dehydration, especially in the very young and elderly. Individuals with severe diarrhea should drink lots of liquids. Symptoms that are not seen with norovirus infection are bloody diarrhea or high fever. If these symptoms develop, contact your medical provider. The best way to limit the spread of these viruses is frequent hand washing for at least 20 seconds using soap and warm running water, being sure to completely clean all areas of hands and under fingernails. This is especially important after using the bathroom or before preparing or eating food. Preventing contamination of food, drinks, water and ice is also very important. People who have been sick with vomiting and diarrhea should not prepare or serve food to others for at least three days after their symptoms are gone. One-third cup of bleach diluted with one gallon of water is the most effective way to disinfect surfaces. Bleach should be used in well-ventilated areas. Hand sanitizers are ineffective against the virus. Norovirus can remain on a variety of surfaces for extended periods of time. Doorknobs, faucets, sinks, toilets, bath rails, phones, counters, chairs, tables, hand rails, light switches, keyboards and other high-touch surfaces should be disinfected more frequently, but especially within a 25-foot radius after a vomiting incident. Steam clean carpets and upholstery and launder clothes or linens contaminated with vomit or feces on the hottest setting. Additional information about norovirus can be found at CDC.gov/norovirus.