What is Gastroenteritis?

Nausea, cramps, stomach aches, and diarrhea — these are the uncomfortable signs of gastroenteritis, which is often called the stomach flu^[1]. Despite the moniker, the viruses that cause gastroenteritis are distinct from those that cause the flu. This means getting your flu shot won’t prevent you from catching this infection.

What is viral gastroenteritis? 

Viral gastroenteritis damages the gut, causes inflammation, and makes it harder for the body to absorb water leading to vomiting and or diarrhea and dehydration. Due to their weakened immune system, the stomach flu can lead to complications in children and the elderly. In developing countries, viral gastroenteritis  leads to more than 200,000 deaths of children per year^[1].

Fortunately, the stomach flu doesn’t last long and in most cases, is treatable at home. The infection typically lasts one to three days and treatment involves hydration and over-the-counter medicines that target the other symptoms.

What causes gastroenteritis?

Gastroenteritis can be caused by bacteria, viruses, or parasites. Viral gastroenteritis, normally called the stomach flu, is mostly caused by viruses like norovirus or rotavirus. Viruses are microscopic machines that hijack our body’s cells to make more copies of themselves. The damage that they cause along the way, as well as the body’s immune response lead to the symptoms of this condition.

Can you prevent gastroenteritis?

One of the main ways that the stomach flu passes between individuals is through the oral-fecal route, or by touch rather than airborne spread^[2,3]. This means that viral particles shed in the stool make their way back into the gastrointestinal tract. Good hand hygiene, including washing hands before eating and after using a washroom, and making sure to close the lid on the toilet before flushing will help reduce the spread of the virus^[2,3].

In addition, these viruses can stick to surfaces, food, and water. Making sure to wash your hands before preparing any food, cleaning fruits and vegetables, and ensuring meats are completely cooked before consumption can help stop the spread of stomach flu^[2,3].

One of the most effective ways to prevent one type of viral gastroenteritis in children is rotavirus vaccination^[4]. Since 2006, several safe and effective vaccines against rotavirus infection have been developed for use in children under two years old. They reduce the risk of hospitalization with diarrhea up to 86 percent. Note that this vaccine does not protect against other viruses, such as norovirus. Speak with a pediatrician to learn about what options are available for your child.

Symptoms of gastroenteritis

Both the rota and noro viruses causes similar symptoms which last several days, including^[1]:

• Vomiting. When it encounters something infectious or damaging, the gut responds by attempting to expel it through vomiting. 
• Diarrhea and dehydration^[5]. The rotavirus damages gut cells that would normally absorb water and other electrolytes, leading to diarrhea. 
• Abdominal cramps. Dehydration, damage to the gut and electrolyte imbalances could cause cramping.
• Low appetite. This could be caused by the body’s general “sickness response”, which fires up the immune system but dampers appetite. 
• Fever. This is the body raising the temperature to help the immune system fight off the virus. 

Rotavirus or norovirus? 

Rotavirus is the most common cause of gastroenteritis in children. The first symptom of this form of the stomach flu is vomiting^[1]. Children remain symptomatic for about three days but will continue shedding virus in their stool for up to 10 days, meaning that adults could catch it without careful hand hygiene. However, many people develop immunity to rotavirus infection early in life, so it is usually asymptomatic in adults. 

Norovirus is the most common cause in adults, but also occurs in children. For norovirus infection, vomiting usually follows abdominal cramps and diarrhea^[1]. The norovirus also usually resolves itself within 72 hours or three days.

Treating gastroenteritis

The goal of treating viral gastroenteritis is to rehydrate the body and medicate away any other bothersome symptoms. Treatment includes^[1]:

• Drinking fluids to prevent dehydration. Drinking water, teas, and warm soups can compensate for the fluid loss caused by diarrhea. Sports drinks can help replenish the electrolytes that are lost as well. 
• Medications to prevent vomiting. Over the counter medications like Pepto Bismol or generic formulations with the same active ingredient bismuth subsalicylate can help reduce vomiting.
• Probiotics and prebiotics to treat diarrhea. Probiotics are beneficial microbes that keep the commensal microbes living in the gut healthy. Prebiotics are foods that feed these microbes. Probiotics and prebiotics could reduce the frequency of diarrhea, especially if taken prior to getting sick. 
• Rest. Sleeping and resting helps the body focus on fighting off the infection faster.

What to eat while you’re sick and recovering

Simple and easy to digest carbohydrate based foods, such as bananas, rice, apples, and toast are common dietary recommendations for dealing with bouts of diarrhea. However, studies so far haven’t shown that this diet is actually better for recovery^[1]. If foods can’t be tolerated, ensure that fluids consumed include some carbohydrates and electrolytes. 

For recovery, it is recommended that you eat as normally as possible, starting with small amounts of food^[7]. Avoid highly processed, very spicy, or fried foods while recovering. Some people experience milk lactose intolerance immediately after gastroenteritis and have to limit dairy products for a short period of time. 

When should you see a doctor?

Most cases of viral gastroenteritis are safely treated at home. But in some cases, people might need to speak with their doctor or visit a hospital. These are some signs for concern^[1,6]:

• Difficulty hydrating or retaining fluids orally. In this case, saline or other intravenous fluids are needed to rehydrate. During the hospital admission, staff will carefully monitor your hydration and electrolyte levels. This can also occur as a result of prolonged bouts of diarrhea.
• Fever higher than 39 degrees. High fevers can be dangerous, especially for children, and can cause further dehydration. 
• Uncontrollable vomiting. If you or your child are unable to get vomiting under control, it may be necessary to receive stronger prescription medication. In some cases, it also requires hospital admission.
• Other conditions or comorbidities. Metabolic conditions such as diabetes, as well as pregnancy, and many other medical conditions could put you at extra risk.

Conclusion

Viral gastroenteritis — more commonly known as the stomach flu  — causes nausea, cramps, vomiting, and diarrhea. Improving hand hygiene, food handling practices, and vaccination can reduce the risk of catching the stomach flu. Most cases are treatable at home through hydration and over-the-counter medications.

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References

1. Stuempfig, N.D., Seroy, J. Viral gastroenteritis. (2022). StatPearls. Treasure Island (FL): StatPearls Publishing.
2. Guix, S., Pintó, R. M., & Bosch, A. (2019). Final consumer options to control and prevent foodborne norovirus infections. Viruses, 11(4), 333.
3. Mattison, C. P., Dunn, M., Wikswo, M. E., Kambhampati, A., Calderwood, L., Balachandran, N., … & Hall, A. J. (2021). Non-norovirus viral gastroenteritis outbreaks reported to the national outbreak reporting system, USA, 2009–2018. Emerging Infectious Diseases, 27(2), 560.
4. Burnett, E., Parashar, U. D., & Tate, J. E. (2020). Real-world effectiveness of rotavirus vaccines, 2006–19: a literature review and meta-analysis. The Lancet Global Health, 8(9), e1195-e1202.
5. Crawford, S. E., Ramani, S., Tate, J. E., Parashar, U. D., Svensson, L., Hagbom, M., Franco, M. A., Greenberg, H. B., O’Ryan, M., Kang, G., Desselberger, U., & Estes, M. K. (2017). Rotavirus infection. Nature reviews. Disease primers, 3, 17083.
6. Government du Quebec. Gastroenteritis (stomach flu).
7. Government du Quebec. Foods to eat when you have gastroenteritis.