Is Norovirus Contagious?

  • Medical Author:
    Charles Patrick Davis, MD, PhD

    Dr. Charles "Pat" Davis, MD, PhD, is a board certified Emergency Medicine doctor who currently practices as a consultant and staff member for hospitals. He has a PhD in Microbiology (UT at Austin), and the MD (Univ. Texas Medical Branch, Galveston). He is a Clinical Professor (retired) in the Division of Emergency Medicine, UT Health Science Center at San Antonio, and has been the Chief of Emergency Medicine at UT Medical Branch and at UTHSCSA with over 250 publications.

  • Medical Editor: Melissa Conrad Stöppler, MD
    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD

    Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

Norovirus Incubation Period

Norovirus may have a prolonged infection period that starts even before a patient gets sick. There is a short lag or incubation period (up to two days) between the time that people acquire the virus and the time they get symptoms. People may be contagious during this period.

What is norovirus?

Norovirus is an enterovirus that causes food poisoning symptoms in individuals. It is sometimes termed the "stomach flu," but it is not related to the true flu viruses (influenza viruses) that cause respiratory problems. Norovirus is considered by the U.S. Centers for Disease Control and Prevention (CDC) to be the most common cause of acute gastroenteritis in the United States (about 19-21 million infections per year with about 570-800 deaths). Although most cases are self-limiting, some patients (children or the elderly, for example) may develop dehydration or other serious consequences, including death.

Is norovirus contagious?

Noroviruses are highly contagious. These viruses can easily infect men, women, and children. There are many subtypes of norovirus so that if you are infected with one norovirus type, it does not protect you against infection with one of the other types. The CDC estimates that in the U.S., every person will get about five infections (five different norovirus types) during their lifetime.

What is the contagious period for norovirus?

Individuals are contagious as soon as the symptoms develop and may remain contagious between three days to two weeks after symptoms are gone.

How will I know if I have norovirus?

Norovirus causes diarrhea, nausea, vomiting, and stomach pain; other symptoms may appear such as fever, headache, and/or body aches. Patients usually report feeling extremely ill and weak.

Because norovirus is usually associated with contaminated foods or fluids, usually an outbreak of the disease is seen among many people who have consumed the same contaminated food or liquids. Consequently, you may suspect you have norovirus if people who have consumed the same foods that you have consumed display the same symptoms (for example, cruise-ship passengers). Other outbreaks happen when an infected individual lives in crowded conditions (for example, dorms or barracks).

Most outbreaks of norovirus are diagnosed clinically from the patient's history and physical exam. Viral cultures can prove the diagnosis, but by the time test results are available (a few days), the symptoms are usually decreasing or are gone.

Medically Reviewed by a Doctor on 11/7/2016

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