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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?
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.
How is norovirus transmitted?
Noroviruses are easily spread to individuals by both direct and indirect contact with infected individuals. Direct contact usually occurs when people are taking care of infected patients (fecal/oral contact by changing diapers and/or bedding, for example). Norovirus can be transmitted or spread indirectly by body secretions (feces, saliva, or vomitus) to other individuals or to foods or liquids; individuals who are food handlers can easily cause outbreaks if they become infected and try to stay on the job. Norovirus can spread rapidly by indirect contact since the virus can remain viable for up to a few days on some surfaces.
Individuals can pass norovirus directly from person to person and indirectly by touching objects (utensils, for example) contaminated with norovirus or eating foods contaminated with norovirus. One study has showed that dogs may get the virus from one individual and then pass the virus to another human.
How will I know I am cured of norovirus?
The symptoms of norovirus infection usually last between 24 to about 72 hours, after which people usually recover completely. Although you may be "cured" of the type of norovirus that infected you, you are still susceptible to infection with other types of noroviruses. Individuals with a suppressed immune system, infants, young children, and the elderly may easily develop dehydration with norovirus infection; those with dehydration need to be treated urgently (with oral or intravenous hydration) to prevent additional problems and prolongation of infection.
When should I contact a medical caregiver about norovirus?
Norovirus infection can cause serious problems in those individuals who have more severe symptoms. Parents of children with signs of dehydration (for example, dry mucus membranes, reduced or no urine production) and adult individuals with similar problems need to contact a medical caregiver urgently. In addition, the following situations should trigger an urgent visit to a physician or an emergency department in any individual who may have norovirus infection:
- Children vomiting for more than one to two days
- Children under the age of 6 months with vomiting and/or diarrhea
- Mental-status changes in children or adults
- Individuals with other underlying medical problems (diabetes, congenital abnormalities, immune compromise, for example)
- Severe abdominal pain
- Blood in diarrhea fluid or vomit
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"Norovirus." Centers for Disease Control and Prevention. Aug. 30, 2016.
Top Is Norovirus Contagious Related Articles
Food PoisoningLearn how look for signs and symptoms food poisoning. Discover ways to keep your food safe from dangers including listeria, E. coli, salmonella and more.
Aches, Pain, FeverAlthough a fever technically is any body temperature above the normal of 98.6 F (37 C), in practice, a person is usually not considered to have a significant fever until the temperature is above 100.4 F (38 C). Fever is part of the body's own disease-fighting arsenal; rising body temperatures apparently are capable of killing off many disease-producing organisms.
DehydrationDehydration is the excessive loss of body water. There are a number of causes of dehydration including heat exposure, prolonged vigorous exercise, and some diseases of the gastrointestinal tract. Symptoms of dehydration include headache, lightheadedness, constipation, and bad breath. Treatment for dehydration is to replace lost fluids and electrolytes.
DiarrheaDiarrhea is a change is the frequency and looseness of bowel movements. Symptoms associated with diarrhea are cramping, abdominal pain, and the sensation of rectal urgency. Causes of diarrhea include viral, bacterial, or parasite infection, gastroenteritis, food poisoning, and drugs. Absorbents and anti-motility medications are used to treat diarrhea.
Food PoisoningFood poisoning is common, but can also be life threatening. The symptoms for food poisoning are fever, abdominal pain, headache, diarrhea, nausea and vomiting. Food poisoning has many causes, for example, chemicals (from toxic fish or plants) and bacteria (Staphylococcus aureus or Salmonella). Treatment of food poisoning depends upon the cause.
Gastroenteritis (Stomach Flu)Stomach flu (gastroenteritis) is a term referred used to describe a variety of gastrointestinal problems. The most common signs and symptoms of gastroenteritis are nausea, vomiting, diarrhea, and abdominal pain. The most common cause of gastroenteritis in the United States is Norovirus. Other causes of gastroenteritis include Rotavirus, Astrovirus, Adenovirus, and Sapovirus. There are bacterial causes of gastroenteritis such as Salmonella, Shigella, Campylobacter Aeromonas, E. coli, Clostridium, Vibrio, Campylobacter, and Yersinia spp. Parasites that cause gastroenteritis include Giardia, Cryptosporidium, Cyclospora, and Entamoeba. Treatment for gastroenteritis is generally home remedies such as keeping hydrated to prevent dehydration. At times, hospitalization may be necessary if dehydration occurs.
Headaches can be divided into two categories: primary headaches and secondary headaches. Migraine headaches, tension headaches, and cluster headaches are considered primary headaches. Secondary headaches are caused by disease. Headache symptoms vary with the headache type. Over-the-counter pain relievers provide short-term relief for most headaches.
Is the Stomach Flu (Gastroenteritis) Contagious
The stomach flu (gastroenteritis) refers to variety infections that occur in the GI (gastrointestinal tract). The stomach flu is caused by viruses (for example, Norovirus or "Cruise Ship Virus), bacteria (for example, Salmonella and E. coli), parasites (for example, Giardiasis or Giardia lamblia), medications like antibiotics, food allergies, and toxins.
Common symptoms of the stomach flu include vomiting, diarrhea, nausea, and abdominal pain. Generally, the stomach flu is treated at home by treating symptoms with home remedies and OTC medication.
Nausea and Vomiting
Nausea is an uneasiness of the stomach that often precedes vomiting. Nausea and vomiting are not diseases, but they are symptoms of many conditions. There are numerous cases of nausea and vomiting. Some causes may not require medical treatment, for example, motion sickness, and other causes may require medical treatment by a doctor, for example, heart attack, lung infections, bronchitis, and pneumonia.
Some causes of nausea and vomiting may be life threatening, for example, heart attack, abdominal obstruction, and cancers.
Treatment of nausea and vomiting depends upon the cause.
Norovirus InfectionNorovirus infection causes stomach flu, or gastroenteritis. It's a very contagious illness with symptoms that include nausea and vomiting, diarrhea, stomach cramps, fever, headache, chills, and muscle aches. Norovirus infection cannot be treated with antibiotics, so treatment focuses on maintaining proper hydration.
Stomach Flu vs. Food Poisoning
The stomach flu (viral gastroenteritis) and food poisoning are not the same infections. However, they do have a few similar symptoms, for example:
- Abdominal (stomach) pain and cramping.
Symptoms and signs of food poisoning show up earlier (2 hours up to a couple of days) in comparison to the stomach flu in which symptoms may take 4 hours up to 48 hours (2 days) before symptoms begin. Medical treatment for the stomach flu and food poisoning generally is not necessary. A bland diet, drinking plenty of fluids, and rest may be the only treatment necessary.