Norovirus gastroenteritis

Disease Description (Causes and Symptoms)

• Cause: An acute gastrointestinal infection caused by norovirus, which is highly contagious and can spread from a small amount of virus. It is mainly transmitted through the fecal–oral route (contaminated food or water, contact with an infected person, or contaminated surfaces), and outbreaks increase during the winter.
• Pathophysiology: Infection of epithelial cells in the small intestine causes villous damage, malabsorption, and secretory changes, resulting in acute vomiting and watery diarrhea. Aerosolized virus may also spread to the surroundings during vomiting.
• Main symptoms: Vomiting, nausea, abdominal pain, diarrhea (watery; mucus and blood are uncommon), fever, chills, muscle aches, headache, and malaise after an incubation period of 24–48 hours. Vomiting tends to be more prominent in children, while diarrhea tends to be more prominent in adults. Most people recover within a few days.

Treatment Methods

• Basic principles: There is no specific antiviral medication. Most people recover naturally with supportive care.
• Fluid and electrolyte replacement: Mild dehydration can be treated with oral rehydration solution (ORS). In cases of vomiting or severe dehydration, intravenous (IV) fluids and electrolyte correction may be necessary.
• Symptom relief: If vomiting is severe, antiemetics (e.g., ondansetron) may be used. Loperamide may be used on a limited basis to relieve diarrhea, depending on a physician’s judgment in certain situations. Antibiotics are not necessary.
• Hospitalization criteria: Severe dehydration, electrolyte abnormalities, or deterioration of general condition in older adults, infants, or immunocompromised individuals.
• Infection control: Properly dispose of the patient’s vomit and feces, and disinfect contaminated surfaces and objects. Wash laundry with soap and hot water. It is recommended to avoid preparing food for 3 days after the patient recovers.
• Environmental disinfection tips (reference RAG): Norovirus is relatively resistant to heat, but it is inactivated by heating at 70°C for 5 minutes or 100°C for 1 minute. Disinfection of surfaces with a strong bleach, such as sodium hypochlorite, is recommended.

Checklist Before an Outpatient Visit (Including Items to Prepare and Example Questions)

Items to prepare/bring

• List of medications currently being taken (including prescription drugs, OTC medications, and supplements)
• Information about underlying conditions (diabetes, heart disease, kidney failure, immunocompromised status, etc.)
• The date and time symptoms began, and a record of how the symptoms have changed over time
• The number and characteristics of vomiting and diarrhea episodes (watery, presence of blood), and whether there is a fever
• Urine output and urination frequency (important for assessing dehydration), and changes in body weight (if possible)
• Recently consumed foods and history of eating out, and whether there are others with symptoms in a group setting (family or workplace)
• Recent test results, if any, or notes from a previous hospital visit

Key questions to tell the doctor in advance during the visit (examples)

• When exactly did the symptoms begin, and how have they progressed?
• How likely is dehydration or an electrolyte abnormality at present?
• What specific fluid-replacement and dietary measures can be taken at home?

General Example Questions to Ask the Doctor

• How long are these symptoms expected to last? When should I expect to recover?
• What are the side effects and precautions for the medication being prescribed (e.g., an antiemetic)?
• Is there any recommendation about when I should take sick leave (or stop handling food)?
• When should I go to the emergency room or return for another visit (e.g., signs of dehydration, bloody stool, little or no urine)?

Example Questions Tailored to the Disease

• Specifically, which disinfectant should be used at home, and how should it be used (such as concentration and contact time)?
• After recovery, when is it safe to resume preparing food or return to a childcare facility or long-term care facility?

(The information above is general guidance summarized based on clinical guidelines and standard practices. Recommendations may vary depending on the individual’s condition, so consult or visit a medical institution if symptoms are severe or concerning.)