Since the introduction of rotavirus vaccines, norovirus is the most common cause of acute sporadic and epidemic viral gastroenteritis in the United States in all age groups, including in children; the peak age is between 6 months and 18 months.
Infections occur year-round in the United States, but most 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 (1).
(See also Overview of Gastroenteritis.)
General reference
1. Mirza S, Hall A: Norovirus. In CDC Yellow Book 2024: Health Information for International Travel. Retrieved from Norovirus | CDC Yellow Book 2024. Accessed March 31, 2025.
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.
Patients may also have fever, headache, and myalgias.
Pearls & Pitfalls
|
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 (antimotility) agents 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) although dilute apple juice or the fluid preferred by the child can be a reasonable option (1). An antiemetic (eg, ondansetron) may be given if vomiting makes oral rehydration difficult, although recommendations are mixed on their use in children ((eg, ondansetron) may be given if vomiting makes oral rehydration difficult, although recommendations are mixed on their use in children (2, 3).
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 ileus or failure of oral rehydration therapy (4). In severe dehydration, IV rehydration should be continued until pulse, perfusion, and mental status normalize.
Antidiarrheal (antimotility) agents should not be given to children < 18 years of age with acute diarrhea (4). 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).
Antibiotics are not useful for norovirus gastroenteritis.
Treatment references
1. Freedman SB, Willan AR, Boutis K, Schuh S. Effect of Dilute Apple Juice and Preferred Fluids vs Electrolyte Maintenance Solution on Treatment Failure Among Children With Mild Gastroenteritis: A Randomized Clinical Trial. JAMA 2016;315(18):1966-1974. doi:10.1001/jama.2016.5352
2. Mirza S, Hall A. Norovirus. In CDC Yellow Book 2024: Health Information for International Travel. Retrieved from Norovirus | CDC Yellow Book 2024. Accessed March 31, 2025.
3. Nino-Serna LF, Acosta-Reyes J, Veroniki AA, Florez ID. Antiemetics in Children With Acute Gastroenteritis: A Meta-analysis. Pediatrics 2020;145(4):e20193260. doi:10.1542/peds.2019-3260
4. Shane AL, Mody RK, Crump JA, et al. 2017 Infectious Diseases Society of America Clinical Practice Guidelines for the Diagnosis and Management of Infectious Diarrhea. Clin Infect Dis 2017;65(12):e45-e80. doi:10.1093/cid/cix669
Key Points
Norovirus is the most common cause of acute viral gastroenteritis in the United States in all age groups.
Clinical course is short but can involve severe vomiting and diarrhea.
Laboratory testing for diagnosis include PCR-based panels and enzyme immunoassays (EIAs).
Oral rehydration is usually adequate, but antiemetics and sometimes IV fluids may be needed.
Antidiarrheal (antimotility) agents 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.
Drugs Mentioned In This Article
