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Norovirus Gastroenteritis

By

Jonathan Gotfried

, MD, Lewis Katz School of Medicine at Temple University

Last full review/revision Sep 2021| Content last modified Sep 2021
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Norovirus is a common cause of diarrhea. Symptoms are vomiting, abdominal cramps, and diarrhea that usually resolve in 1 to 3 days. Diagnosis is based on clinical suspicion, and polymerase chain reaction testing as part of a multiplex panel for a variety of causes of acute gastroenteritis can be done. Treatment is supportive with oral fluids; in more severe cases, IV fluids may be needed.

Since the introduction of rotavirus vaccines, norovirus has become the most common cause of acute sporadic and epidemic viral gastroenteritis in the US in all age groups, including in children; the peak age is between 6 months and 18 months. Infections occur year-round, but 80% occur from November to April. Large waterborne and foodborne outbreaks occur. Person-to-person transmission also occurs because the virus is highly contagious. Norovirus causes most cases of gastroenteritis epidemics on cruise ships and in nursing homes. Incubation period is 24 to 48 hours.

Symptoms and Signs of Norovirus Gastroenteritis

Norovirus typically causes acute onset of vomiting, abdominal cramps, and diarrhea, with symptoms usually lasting 1 to 3 days. In children, vomiting is more prominent than diarrhea, whereas in adults, diarrhea usually predominates. Fluid losses vary from mild to severe dehydration Dehydration in Children Dehydration is significant depletion of body water and, to varying degrees, electrolytes. Symptoms and signs include thirst, lethargy, dry mucosa, decreased urine output, and, as the degree... read more .

Patients may also have fever, headache, and myalgias.

Diagnosis of Norovirus Gastroenteritis

  • Sometimes reverse transcriptase–polymerase chain reaction (RT-PCR) testing

Diagnosis of norovirus is usually based on clinical suspicion in a patient with typical symptoms, especially during an outbreak.

Laboratory testing can confirm the diagnosis of norovirus infection using RT-PCR on a stool sample. This test is usually done as a multiplex PCR panel including a number of causes of gastroenteritis. Caution must be used when interpreting a positive test result for norovirus because there can be asymptomatic shedding, which the very sensitive PCR test can detect. A positive test result for norovirus in a patient with atypical symptoms, such as bloody diarrhea, or in a patient testing positive for another pathogen suggests that norovirus is not the cause of the gastroenteritis.

Treatment of Norovirus Gastroenteritis

  • Oral or IV fluids

  • Sometimes antidiarrheal drugs and/or antiemetics

Supportive care, including rehydration with fluids and electrolytes, is the mainstay of treatment and is all that is needed for most adults. Oral glucose-electrolyte solutions, broth, or bouillon may prevent dehydration or treat mild dehydration. Children may become dehydrated more quickly and should be given an appropriate oral rehydration solution (several are available commercially—see Oral Rehydration Oral Rehydration Oral fluid therapy is effective, safe, convenient, and inexpensive compared with IV therapy. Oral fluid therapy is recommended by the American Academy of Pediatrics and the WHO and should be... read more ). An antiemetic (eg, ondansetron) may be given if vomiting makes oral rehydration difficult.

Isotonic IV fluids such as Ringer’s lactate and normal saline solution should be given when there is severe dehydration, hypovolemic shock, or altered mental status and failure of oral rehydration therapy or ileus (see also the Infectious Diseases Society of America's [IDSA] 2017 clinical practice guidelines for the diagnosis and management of infectious diarrhea). In severe dehydration, IV rehydration should be continued until pulse, perfusion, and mental status normalize.

Antidiarrheal agents should not be given to children < 18 years of age with acute diarrhea (see the IDSA guidelines). Antidiarrheals can be considered in adult patients with watery diarrhea (as shown by heme-negative stool), especially during an outbreak, suggesting a viral cause is likely. However, antidiarrheals may cause deterioration of patients with Clostridioides difficile or E. coli O157:H7 infection and thus should not be given to any patients in whom the cause of diarrhea has not been identified and in whom these disorders may be suspected (ie, based on recent antibiotic use, bloody diarrhea, heme-positive stool, or diarrhea with fever).

Key Points

  • Norovirus is the most common cause of acute viral gastroenteritis in the US in all age groups.

  • Clinical course is short but can involve severe vomiting and diarrhea.

  • Oral rehydration is usually adequate, but antiemetics and sometimes IV fluids may be needed.

  • Antidiarrheals are safe for adults with watery diarrhea but should be avoided in children < 18 years of age and in any patient with recent antibiotic use, bloody diarrhea, heme-positive stool, or diarrhea with fever.

More Information

The following is an English-language resource that may be useful. Please note that THE MANUAL is not responsible for the content of this resource.

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