Stomach Flu (viral gastroenteritis): Causes & Treatment

Stomach flu is a viral infectious disease, that affects the stomach and intestines. The medical term is viral gastroenteritis or gastroenteritis. “Gastro” means stomach and “enter” means small intestine. “Itis” means inflammation, which is usually due to an infection. And “viral” means that a virus has caused the infection.

The most common way to develop stomach flu (gastroenteritis) is through contact with an infected person or by consuming contaminated food or water. If you’re otherwise healthy, you’ll likely recover without complications. But for infants, older adults and people with compromised immune systems, stomach flu can be deadly.

Stomach flu is extremely common worldwide, but it’s hard to estimate exactly how many people get it each year. Many more viruses can cause it, and most people don’t get clinically tested for it. Health professionals estimate that norovirus, the most common cause, infects 685 million people every year.

Symptoms of stomach flu

For many people, stomach flu symptoms seem to come on suddenly and out of nowhere. You might throw up or have diarrhea many times on that first day.

Stomach flu(gastroenteritis) attacks your intestines, causing signs and symptoms such as:

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

With the cause, viral gastroenteritis symptoms may appear within 1-3 days after you’re infected and can range from mild to severe. Symptoms usually last just a day or two, but occasionally they may last up to 14 days.

Because the symptoms are similar, it’s easy to confuse viral diarrhea with diarrhea caused by bacteria, such as Clostridioides difficile, salmonella and Escherichia coli, or parasites, such as giardia.

Other symptoms may include:

• Fever.
• Chills.
• Fatigue.
• Body aches.
• Headaches.
• Swollen lymph nodes.

When to seek medical attention:

• You’re not able to keep liquids down for 24 hours
• You’ve been vomiting (can also be blood) or having diarrhea for more than two days
• 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 have severe stomach pain and also a fever above 104 F (40 C)

Also seek medical attention for your children or infants if:

• Has a fever of 102 F (38.9 C) or higher
• Seems tired or very irritable
• Has bloody diarrhea & also looks dehydrated

Nursing a child or 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.

You can also read about the causes and symptoms of syphilis.

Causes of stomach flu

There are many types of viruses that can cause viral gastroenteritis. This include:

• Noroviruses. Noroviruses are the most common cause of stomach flu worldwide, accounting for around 50 percent of cases and over 90 percent of outbreaks. They’re very contagious and are mostly transmitted via the fecal-oral route. People typically contract the infection by consuming contaminated food or water. You can also get it through indirect contact, such as touching a surface after a person with norovirus touched it. Restaurants and other food service settings are responsible for more norovirus outbreaks than any other type of setting.
• Rotaviruses. The infection rotavirus is more common in children than in adults. Rotaviruses can live on surfaces and the virus can also be transmitted through indirect contact or airborne transmission. Most people with rotavirus contract it after handling the stool of someone with the infection. While rotavirus still affects many children, cases and outbreaks have seen a steep decline since a vaccine was introduced in 2006.
• Adenoviruses. Like rotavirus, adenovirus infections primarily affect young children. However, this infection is less common. Adenoviruses are airborne. You can also get the infection through personal contact (such as shaking hands) or by touching a contaminated surface.
• Sapoviruses. Sapoviruses belong to the same virus family as noroviruses. They’re most common in children under 5 years old. Consuming contaminated food or water or coming into contact with the stool or vomit of someone with sapovirus can cause an infection.
• Astroviruses. Astroviruses also mainly affect children. They’re transmitted via the fecal-oral route. Drinking contaminated water can result in an astrovirus infection.

Stages of stomach flu

The following are the stages of gastroenteritis:

• Exposure. You’re most likely to get the viral gastroenteritis from someone in your community, especially in a closed environment like a school, nursing home or cruise ship. Since symptoms take some time to develop, you might hear about an outbreak later, after you were exposed.
• Incubation. Once you’ve contracted the virus, it’ll begin replicating inside your body. This is the incubation period. You won’t have symptoms until the virus replicates enough to alert your immune system. This usually takes a few days, depending on the virus.
• Acute infection. Viral gastroenteritis is an acute infection, which means it’s sudden and temporary. When your immune system registers the threat, it activates an inflammatory response to clear the virus. This is what causes symptoms of illness. When it succeeds, the symptoms will stop.
• Recovery. You’ll notice your symptoms lessening when your immune system has won the battle against the virus. Eventually, your symptoms will stop, and you’ll feel better. But you may continue to shed the virus in your poop (stool) for a few days, which means you’re still contagious.

You can also read about causes and transmission of Japanese encephalitis.

Transmission of stomach flu

The viruses that cause viral gastroenteritis are present in stool and vomit. These viruses can contaminate your food, water, and surfaces, especially if a person doesn’t practice proper hand hygiene after using the restroom.

You’re at risk of getting infected if you:

• touch a surface or object that contains the virus, and then touch your face or mouth
• consume food or water that contain the virus
• have close contact with someone with stomach flu

The norovirus in particular is so resilient it can survive for 2 weeks on surfaces and for 2 months or more in water. It can also withstand temperature changes and many common cleaning products. This can make it easier to spread from one person to another.

Risk factors of stomach flu

Viral gastroenteritis can occur anywhere and can affect people of all ages. Those who are more susceptible to it include:

• People with weakened immune system. If your resistance to infection is low, for instance, when your immune system is compromised by HIV/AIDS, chemotherapy or another medical condition, you may be especially at risk.
• Older people and adults. Adult immune systems tend to become less efficient later in life. Older adults in nursing homes are vulnerable because their immune systems weaken. They also live in close contact with others who may pass along germs.
• Young children or infants. Children in child care centers or elementary schools may be especially vulnerable because it takes time for a child’s immune system to mature.
• 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.

Each virus causing gastroenteritis has a season when it’s most active. If you live in the Northern Hemisphere, for instance, you’re most likely to have rotavirus or norovirus infections in the spring and winter.

Complications of stomach flu

Those with weaker immune system functions may have a severe infection and more likely to get or experience complications.

The most common complication of stomach flu is dehydration. This can happen when you lose too many fluids and electrolytes from diarrhea or vomiting, and you can’t drink enough or drink fast enough to replace them.

People with weaker immune systems (especially children) are more likely to become dehydrated, and it can be very dangerous for them. Stay alert for signs of dehydration, which can include:

• Lack of urine (pee) or dark-colored urine.
• Thirst.
• Lack of poop or hard, dry poop.
• Weakness or malaise.
• Sunken eyes.
• Dehydration headache.
• Dry lips and tongue.
• Crying without tears.

You can also read about risk factors and complications of typhoid fever.

Prevention of stomach flu

The proper way of preventing yourself from getting the spread of viral gastroenteritis is to follow the precautions below:

• Get vaccinated. There are two vaccines available to help prevent rotavirus infections in infants. It’s recommended that infants receive the first dose of the vaccine by 15 weeks of age and all vaccine doses by 8 months. An adenovirus vaccine is available for members of the U.S. military who are between 17 and 50 years old.
• Disinfect. If someone in your house experiences vomiting or diarrhea due to stomach flu, thoroughly disinfect and clean the area afterward. Use 5 to 25 tablespoons of bleach per gallon of water or another household cleaner approved for viruses such as norovirus.
• Wash your hands frequently. Wash your hands thoroughly after using the restroom or changing a diaper, before eating or handling food, and after touching surfaces or objects that may contain viruses.
• Keep surfaces clean. Focus on high-touch surfaces, such as doorknobs, appliance handles, remote controls, light switches, and countertops.
• Practice food safety. Wash all fresh produce before eating it. Make sure all foods are cooked to the appropriate temperature before consuming. Always handle or prepare food on a clean surface.
• Clean soiled laundry. If a person in your household has stomach flu, promptly clean soiled clothing, bedding, or towels promptly. Wash with detergent and hot water and use a clothes dryer.

How to prevent the spread of infection to other people in your environment or when traveling:

• Wash your hands thoroughly. This is particularly important after you’ve used the restroom and if you have diarrhea or vomiting.
• Keep your distance. Avoid coming into contact with people who are at an increased risk of serious illness. This includes babies, older adults, and people with a weakened immune system.
• Don’t share. Avoid sharing items such as eating utensils, drinking glasses, phones, or towels while you’re sick and for several days after your symptoms have subsided.
• Avoid handling food. Try not to handle or prepare food while you’re sick and for at least 2 days after your symptoms have gone away.
• Stay home. Plan to stay home from work or school for at least 2 days after your symptoms have subsided.

Diagnosis of stomach flu

Your healthcare provider will likely diagnose viral gastroenteritis (stomach flu) based on:

• A physical exam. Your doctor will examine your symptoms and sometimes on the presence of similar cases in your community.

• A rapid stool test. This test can detect rotavirus or norovirus, but there are no quick tests for other viruses that cause gastroenteritis. In some cases, your doctor may have you submit a stool sample to rule out a possible bacterial or parasitic infection.

You can also read about prevention and diagnosis of cholera.

Treatment of stomach flu

Your immune system gets rid of stomach flu through its own natural processes. It just takes a few days to do its work. Your symptoms, while unpleasant, are a sign that your immune system is working. The best thing you can do to help your immune system do its work is to stay home and rest, stay hydrated and eat a little if you can.

Medical treatment involves managing your symptoms and promoting hydration. You may be given intravenous (IV) fluids to help replace lost fluids and electrolytes. In some cases, healthcare providers may prescribe medications to reduce vomiting or diarrhea in adults.

Depending on the severity of the above symptoms, a healthcare professional might suspect bacterial gastroenteritis instead. In this case, they may perform a stool culture or prescribe antibiotics. They may also monitor your bloodwork for signs of infection, such as a high white blood cell count.

Most people recover without seeking medical attention. However, if you experience signs of serious dehydration, blood in your stool, persistent fever, or severe abdominal pain, get medical attention right away.

Home remedies

The following home remedies can help you or your child ease the symptoms of viral gastroenteritis and prevent more severe illness.

• Let your stomach settle. Stop eating solid foods for a few hours.
• Drink plenty of fluids. Diarrhea and vomiting can lead to dehydration. Aim to replace lost fluids and electrolytes by regularly drinking water, sports drinks, or broths.
• 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.
• 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.

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