Stomach Flu ( Viral Gastroenteritis )

Viral gastroenteritis is an intestinal infection that includes signs and symptoms such as watery diarrhea, stomach cramps, nausea or vomiting, and sometimes fever.

Overview

Viral gastroenteritis, sometimes known as the stomach flu, is most frequently contracted by direct contact with an infected person or by ingesting tainted food or drink. You'll probably recover smoothly if you're otherwise healthy. Viral gastroenteritis, however, has the potential to be fatal in young children, the elderly, and those with weakened immune systems.
There's no effective treatment for viral gastroenteritis, so prevention is key. Avoid food and water that may be contaminated and wash your hands thoroughly and often.

Alternative Names

Rotavirus infection; Norwalk virus; Gastroenteritis - viral; Stomach flu

Causes

Gastroenteritis can affect a single individual or a group of people who all consumed the same meal or water can develop gastroenteritis. The germs may enter your body directly through food or water or indirectly through things like plates and eating utensils. They can also be spread by direct touch from one individual to another.

In both adults and children, viral gastroenteritis is the most common cause of severe diarrhoea. Gastroenteritis can be brought on by a wide variety of viruses. The most typical ones are:

• Norovirus (Norwalk-like virus) is common among school-age children. It may also cause outbreaks in hospitals and on cruise ships.
• Rotavirus is the leading cause of severe gastroenteritis in children. It can also infect adults who are exposed to children with the virus, and people living in nursing homes.
• Astrovirus
• Enteric adenovirus

People with the highest risk for severe gastroenteritis include young children, the elderly, and people who have a suppressed immune system.

Symptoms

Although it's commonly called stomach flu, gastroenteritis isn't the same as influenza. The flu (influenza) affects only your respiratory system your nose, throat and lungs. Gastroenteritis, on the other hand, attacks your intestines, causing signs and symptoms such as:

• Watery, usually nonbloody diarrhea — bloody diarrhea usually means you have a different, more severe infection
• Nausea, vomiting or both
• Stomach cramps and pain
• Occasional muscle aches or headache
• Low-grade fever

Viral gastroenteritis symptoms can range from mild to severe and can manifest between 1-3 days of infection, depending on the cause. The typical duration of symptoms is a day or two, although on rare occasions they might persist up to 14 days.
Because the symptoms are similar, it is simple to mistake viral diarrhoea for diarrhoea brought on by bacteria or parasites like giardia or parasitic worms like salmonella, clostridioides difficile, and escherichia coli.

When to see a doctor

If you're an adult, call your health care provider if:

• You're not able to keep liquids down for 24 hours
• You've been vomiting or having diarrhea for more than two days
• You're vomiting blood
• You're dehydrated — signs of dehydration include excessive thirst, dry mouth, deep yellow urine or little or no urine, and severe weakness, dizziness or lightheadedness
• You notice blood in your bowel movements
• You have severe stomach pain
• You have a fever above 104 F (40 C)
• For infants and children

See your child's health care provider right away if your child:

• Has a fever of 102 F (38.9 C) or higher
• Seems tired or very irritable
• Is in a lot of discomfort or pain
• Has bloody diarrhea
• Seems dehydrated — watch for signs of dehydration in sick infants and children by comparing how much they drink and urinate with how much is normal for them, and watching for signs such as a dry mouth, thirst and crying without tears.

If you have an infant, remember that while spitting up may be an everyday occurrence for your baby, vomiting is not. Babies vomit for a variety of reasons, many of which may require medical attention.
Call your baby's doctor right away if your baby:

• Has vomiting that is frequent
• Hasn't had a wet diaper in six hours
• Has bloody stools or severe diarrhea
• Has a sunken soft spot (fontanel) on the top of his or her head
• Has a dry mouth or cries without tears
• Is unusually sleepy, drowsy or unresponsive.

Risk factors

Gastroenteritis occurs all over the world and can affect people of all ages.
People who may be more susceptible to gastroenteritis include:

• Young children. Due to the length of time it takes for a child's immune system to develop, children attending daycare facilities or elementary schools may be particularly at risk.
• Older adults. The effectiveness of adult immune systems typically declines with age. Because of their weakened immune systems, elderly residents of nursing homes are vulnerable. Additionally, they are in close proximity to people who could spread viruses.
• Schoolchildren or dormitory residents.Anywhere that groups of people come together in close quarters can be an environment for an intestinal infection to get passed.
•  Anyone with a weakened immune system. If your resistance to infection is low  for instance, if your immune system is compromised by HIV/AIDS, chemotherapy or another medical condition  you may be especially at risk.

There is a season when a certain digestive virus is most prevalent. For example, rotavirus and norovirus infections are more prevalent in the winter and spring if you live in the Northern Hemisphere.

Complications

Dehydration, or a serious loss of water and vital salts and minerals, is the most common side effect of viral gastroenteritis. Dehydration shouldn't be an issue if you're in good health and consume enough liquids to make up for the fluids you lose from vomiting and diarrhoea.
When they lose more fluids than they can replace, infants, elderly individuals, and persons with compromised immune systems are particularly susceptible to dehydration. It may be necessary to stay in the hospital so that lost fluids can be restored via an IV in their arms. Rarely can dehydration result in death.

Take precautions when traveling

When you're traveling in other countries, you can become sick from contaminated food or water. You may be able to reduce your risk by following these tips:

• Drink only well-sealed bottled or carbonated water.
• Avoid ice cubes because they may be made from contaminated water.
• Use bottled water to brush your teeth.
• Avoid raw food — including peeled fruits, raw vegetables and salads — that has been touched by human hands.
• Avoid undercooked meat and fish.

Diagnosis

The health care provider will look for signs of dehydration, including:

• Dry or sticky mouth
• Lethargy or coma (severe dehydration)
• Low blood pressure
• Low or no urine output; concentrated urine that looks dark yellow
• Markedly sunken soft spots (fontanelles) on the top of an infant's head
• No tears
• Sunken eyes

Tests of stool samples may be used to identify the virus that is causing the sickness. Most of the time, this test is not needed for viral gastroenteritis. A stool culture may be done to find out if the problem is being caused by bacteria.

Treatment

The goal of treatment is to prevent dehydration by making sure the body has enough water and fluids. Fluids and electrolytes (salt and minerals) that are lost through diarrhea or vomiting must be replaced by drinking extra fluids. Even if you are able to eat, you should still drink extra fluids between meals.

• Older children and adults can drink sports beverages such as Gatorade, but these should not be used for younger children. Instead, use the electrolyte and fluid replacement solutions or freezer pops available in food and drug stores.
• Do NOT use fruit juice (including apple juice), sodas or cola (flat or bubbly), Jell-O, or broth. These liquids do not replace lost minerals and can make diarrhea worse.
• Drink small amounts of fluid (2 - 4 oz.) every 30 - 60 minutes. Do not try to force down large amounts of fluid at one time, which can cause vomiting. Use a teaspoon or syringe for an infant or small child.
• Babies can continue to drink breast milk or formula along with extra fluids. You do NOT need to switch to a soy formula.

Try eating small amounts of food frequently. Foods to try include:

• Cereals, bread, potatoes, lean meats
• Plain yogurt, bananas, fresh apples
• Vegetables

If you have diarrhea and are unable to drink or keep down fluids because of nausea or vomiting, you may need fluids through a vein (IV). Infants and young children are more likely to need IV fluids.

Parents should closely monitor the number of wet diapers an infant or young child has while sick to watch for signs of dehydration.

People taking water pills (diuretics) who develop diarrhea may be told by their health care provider to stop taking the diuretic during the acute episode. However, DO NOT stop taking any prescription medicine without first talking to your health care provider.

Antibiotics do not work for viruses.

You can buy medicines at the drugstore that can help stop or slow diarrhea.

• Do not use these medicines without talking to your health care provider if you have bloody diarrhea, a fever, or if the diarrhea is severe.
• Do not give these medicines to children.

What to expect from your doctor

Some questions the doctor may ask include:

• When did symptoms begin?
• Have the symptoms been continuous, or do they come and go?
• How severe are the symptoms?
• What, if anything, seems to improve symptoms?
• What, if anything, appears to worsen symptoms?
• Have you been in contact with anyone with similar symptoms?

Lifestyle and home remedies

To help keep yourself more comfortable and prevent dehydration while you recover, try the following:

• Let your stomach settle. Stop eating solid foods for a few hours.
• Try sucking on ice chips or taking small sips of water often. You might also try drinking clear soda, clear broths or noncaffeinated sports drinks. In some cases you can try oral rehydration solutions. Drink plenty of liquid every day, taking small, frequent sips.
• Ease back into eating. As you're able, you can return to eating your normal diet. You might find that you can eat bland, easy-to-digest foods at first, such as soda crackers, soup, oats, noodles, bananas and rice. Stop eating if your nausea returns.
• Avoid certain foods and substances until you feel better. These include caffeine, alcohol, nicotine, and fatty or highly seasoned foods.
• Get plenty of rest. The illness and dehydration may have made you weak and tired.
• Try anti-diarrhea medications. Some adults may find it helpful to take loperamide (Imodium A-D) or bismuth subsalicylate (Pepto-Bismol, others) to manage their symptoms. However, avoid these if you have bloody diarrhea or fever, which could be signs of another condition.

For infants and children

When your child has an intestinal infection, the most important goal is to replace lost fluids and salts. These suggestions may help:

• Help your child rehydrate. Give your child an oral rehydration solution, available at pharmacies without a prescription. Talk to your doctor if you have questions about how to use it.

Don't give your child plain water — in children with gastroenteritis, water isn't absorbed well and won't adequately replace lost electrolytes. Avoid giving your child apple juice for rehydration — it can make diarrhea worse.

• Get your child back to a normal diet once hydrated. Once your child is rehydrated, introduce him or her to his or her normal diet. This might include toast, yogurt, fruits and vegetables.
• Avoid certain foods. Don't give your child sugary foods, such as ice cream, sodas and candy. These can make diarrhea worse.
• Make sure your child gets plenty of rest. The illness and dehydration may have made your child weak and tired.
• Avoid giving your child store-bought anti-diarrheal medications, unless advised by your doctor. They can make it harder for your child's body to get rid of the virus.

If you have a sick infant, let your baby's stomach rest for 15-20 minutes after vomiting or a bout of diarrhea, then offer small amounts of liquid. If you're breast-feeding, let your baby nurse. If your baby is bottle-fed, offer a small amount of an oral rehydration solution or regular formula. Don't dilute your baby's already-prepared formula.

Actions you can take in the interim

Drink a lot of water. You can resume eating your regular diet as soon as you're able. At first, you might discover that you can eat bland, easily digestible foods. The same strategy applies to ill children: provide lots of fluids. Start introducing your child to his or her regular diet as soon as you can. Continue feeding your child normally whether you are breastfeeding or using formula. Consult your child's doctor to determine whether using an oral rehydration solution, which is sold without a prescription at pharmacies, will be beneficial.

References:

• Norovirus. Centers for Disease Control and Prevention. https://www.cdc.gov/norovirus/.
• Rotavirus. Centers for Disease Control and Prevention. https://www.cdc.gov/rotavirus/index.html. 
• Viral gastroenteritis ("stomach flu"). National Institute of Diabetes and Digestive and Kidney Diseases. https://www.niddk.nih.gov/health-information/digestive-diseases/viral-gastroenteritis/definition-facts. 
• O'Ryan MG. Acute viral gastroenteritis in children in resource-rich countries: Management and prevention. https://www.uptodate.com/contents/search.
• Choose safe food and drinks when traveling. Centers for Disease Control and Prevention. https://wwwnc.cdc.gov/travel/page/food-water-safety.