Viral Gastroenteritis

Overview

Viral gastroenteritis, often called the "stomach flu," is an infection of the stomach and intestines caused by a virus. Despite the nickname, it is not related to influenza, which affects the respiratory system. It is very common and usually short-lived, but it spreads easily and can cause significant fluid loss.

Several viruses cause it, including norovirus, which often spreads in outbreaks, and rotavirus, a leading cause in young children. Most people recover within a few days without specific treatment, and the main goal is to prevent and treat dehydration.

Symptoms

Symptoms usually appear within 1 to 3 days of infection and last a few days. They commonly include:

• Watery, non-bloody diarrhea
• Nausea and vomiting
• Stomach cramps and pain
• Low-grade fever, headache, and muscle aches in some people

Watch for signs of dehydration, including extreme thirst, dry mouth, dizziness, dark urine, passing little urine, and, in children, fewer wet diapers, no tears when crying, and unusual drowsiness or irritability.

Causes

Viral gastroenteritis is caused by viruses that infect the lining of the digestive tract. It spreads through:

• Contaminated food or water
• Touching surfaces or objects carrying the virus and then touching the mouth
• Close contact with an infected person, including sharing food or utensils

Common culprits include norovirus, rotavirus, adenovirus, and astrovirus. The viruses are highly contagious and can spread quickly in households, schools, cruise ships, and care facilities.

Risk Factors

• Young children and infants, especially before rotavirus vaccination
• Older adults, particularly in care settings
• Weakened immune system
• Close-contact environments such as schools, dormitories, and cruise ships
• Poor hand hygiene and contaminated food or water

Diagnosis

Viral gastroenteritis is usually diagnosed from the symptoms and a physical exam, without special tests. Additional testing may be done in certain situations:

• Stool tests: Used during outbreaks or if a bacterial or parasitic cause is suspected, especially with bloody diarrhea or high fever.
• Assessment of hydration: Checking pulse, blood pressure, and other signs to gauge fluid loss, particularly in children and older adults.

Treatment

There is no specific cure; antibiotics do not work against viruses. Care focuses on rest and replacing lost fluids.

• Rehydration: Drink small, frequent sips of water and use oral rehydration solutions to replace water and salts. These are especially important for children and older adults.
• Gradual return to food: Start with bland, easy-to-digest foods as nausea improves.
• Rest while symptoms settle.
• Intravenous fluids: Needed in cases of severe dehydration that cannot be managed by drinking.

Anti-diarrheal and anti-nausea medicines are sometimes used in adults but should be used cautiously, and not in children without medical advice.

Prevention

• Wash hands thoroughly with soap and water, especially after using the bathroom and before eating or preparing food
• Clean and disinfect contaminated surfaces, since hand sanitizer is less effective against some viruses like norovirus
• Avoid sharing food, drinks, and utensils with someone who is ill
• Stay home while sick and for a couple of days after symptoms resolve
• Vaccinate infants against rotavirus as recommended

When to See a Doctor

Seek medical care if you cannot keep liquids down for 24 hours, have diarrhea for more than a few days, notice blood in vomit or stool, have a high fever, or show signs of dehydration such as dizziness, very dark urine, or little urination. For infants and young children, seek care promptly for persistent vomiting, no wet diapers for several hours, no tears when crying, sunken eyes, or unusual sleepiness, as children can become dehydrated quickly.

Related Topics

Frequently Asked Questions

References

1. Centers for Disease Control and Prevention (CDC). Norovirus.
2. MedlinePlus, U.S. National Library of Medicine. Viral gastroenteritis.
3. Mayo Clinic. Viral gastroenteritis (stomach flu).
4. World Health Organization (WHO). Diarrhoeal disease.