The stomach flu is likely caused by norovirus, a group of related viruses affecting the gastrointestinal tract. This highly contagious virus has several strains and spreads quickly from person to person, causing mayhem and illness.

Anyone can become ill with the norovirus at any time throughout the year. However, more outbreaks in the United States occur during winter, typically beginning in November and ending in April. The seasonality of norovirus is likely due in part to people spending more time indoors in close proximity during winter months, thereby increasing the chance of spreading the virus.

Individuals infected with the virus will show symptoms within 12 to 48 hours after exposure. Symptoms can range in severity, including body aches, abdominal pain, low-grade fever, tiredness, nausea, vomiting, and diarrhea. The duration of the illness typically lasts between 24 to 60 hours. Like other viruses, there is no treatment for norovirus; it must run its course. If persons affected are otherwise healthy, they will recover completely with no long-term health effects.

However, children under five, adults aged 85 years and older, expectant mothers, and those with a compromised immune system are at greater risk of experiencing more severe symptoms, which may lead to serious health problems. Drink plenty of liquids to prevent dehydration from fluids lost due to vomiting and diarrhea. Contact a healthcare provider immediately to seek medical treatment for symptoms such as severe vomiting, bloody stools, lethargy, dizziness, or low urine output.

Most people will become infected with norovirus at some point in their lifetime; studies indicate that more than 60 percent of the U.S. population will be exposed to at least one of these viruses by age 50. Being prepared can help to minimize the risk of spreading the infection to others.

Tips to prevent the spread of norovirus

• Wash hands: Handwashing is one of the best ways to prevent the spread of bacteria and viruses. Wet hands with clean running water, apply soap, and scrub hands for at least 20 seconds. Make sure to lather the backs of hands, between fingers, and under fingernails. Rinse hands under clean running water and dry them using a clean towel.
• When sick, stay home: Individuals infected with norovirus are contagious from when they begin to feel ill until at least three days after symptoms have resolved. Avoid being around others for travel, school, and work until at least 48 hours after symptoms have stopped.
• Do not prepare food for others when sick: The majority of norovirus outbreaks come from food and beverages that have been contaminated by someone handling food that is infected. Do not prepare food for others when sick until 48 hours after symptoms have stopped.
• Clean and disinfect contaminated surfaces: Use a chlorine bleach solution or other disinfectant registered as effective against norovirus by the U.S. Environmental Protection Agency (EPA). Norovirus can be spread through the air; to decrease the risk of contamination, clean and disinfect not only the soiled area but also an additional 25-feet radius around it.
• Use care around soiled items: Handle soiled items carefully, wear disposable gloves when cleaning contaminated areas, and always wash hands afterward.
• Wash clothes and linens separately: Remove any vomit or feces before washing items and wash as soon as possible. Wash items with laundry detergent and hot water at the maximum available cycle level length, and dry items using the highest heat setting on your dryer.
• Skip hand sanitizer: Hand sanitizers are ineffective against norovirus. Instead, wash hands with soap and water, scrubbing for at least 20 seconds. Use hand sanitizers in addition to handwashing to prevent transmission of other types of bacteria and viruses.

SOURCE: Diane Reinhold, Nutrition and Wellness Educator, University of Illinois Extension