Noroviruses are estimated to cause 23 million cases of acute gastroenteritis (commonly called the "stomach flu") in the U.S. each year, and are the leading cause of gastroenteritis. Of viruses, only the common cold is reported more often than viral gastroenteritis (norovirus).  Click below for handy download:

Noroviruses may cause more outbreaks of foodborne illness than all bacteria and parasites. They can cause extended outbreaks because of their high infectivity, persistence in the environment, resistance to common disinfectants, and difficulty in controlling their transmission through routine sanitary measures.

The norovirus is transmitted primarily through the fecal-oral route and fewer than 100 norovirus particles are said to be needed to cause infection. Transmission occurs either person-to-person or through contamination of food or water. Transmission can occur by touching surfaces or objects contaminated with norovirus and then placing that hand in your mouth; having direct contact with another person who is infected and showing symptoms; sharing foods or eating utensils with someone who is ill; exposure to aerosolized vomit; and consuming food contaminated by an infected food handler.

The virus is shed in large numbers in the vomit and stool of infected individuals, most commonly while they are ill. Some individuals may continue to shed norovirus up to two weeks after they have recovered from the illness.

  • Algerine

    Nice guide, but I hope this is just a draft. You have norovirus capitalized when it doesn’t need to be and the text is a little too technical, in my opinion. You may want to “dumb it down” a bit. Here’s how I would have written the first couple of parts:
    Norovirus, sometimes called Norwalk or Norwalk-like virus (NLV), is responsible for as many as 23 million episodes of acute gastrointestinal illness in the U.S. each year. Norovirus is highly infectious, and can spread rapidly, especially in contained environments
    such as cruise ships and nursing homes.
    Norovirus enters the body through the mouth. A person may become infected by consuming food or water contaminated with norovirus; touching contaminated surfaces or objects and then placing that hand in your mouth; or having contact with another person who is infected and showing symptoms, including breathing in airborne particles after the ill person has thrown up or has had diarrhea, or sharing foods or eating utensils with someone who is ill, including ill food handlers.
    Unlike many other viruses, people do not develop an immunity to norovirus; you can become sick again.
    Hope that helps.

  • Algerine

    p.s. Don’t know if you’ve seen it, but the CDC has released their draft guidelines for noro outbreaks in healthcare settings. It’s at It’s a fun read.

  • Angelina

    Best Food Safety Training for staff at the lowest cost. Food Safety training program proves extremely cost effective for companies in the Manufacturing; Catering and Retail industries. Visit