Gastroenteritis: Causes, Symptoms, Complications, Diagnosis, Treatment and Prevention

It is inflammation of the stomach or intestines (the gastrointestinal tract).

It is usually caused by an infection.

Gastroenteritis can cause diarrhea, make a person feel sick, vomit, and have pain in the abdomen.

When gastroenteritis is viral, this illness is sometimes called the intestinal flu.

Extremely widespread, especially in children, gastroenteritis is also highly contagious.

Bacterial gastroenteritis is also called “food poisoning”; it results from improper food preparation or preservation.

Causes of gastroenteritis

The leading causes of gastroenteritis are infections caused by a virus, bacteria, or parasite.


Less often, you can get gastroenteritis as a side effect of some medications or from ingesting toxins.

For viruses

Viruses are the most common cause of gastroenteritis, particularly in children. These include:

  • Rotavirus – This is the most common cause of gastroenteritis in babies. Rotavirus mainly affects young children between the ages of 3 and 15 months.
  • Norovirus – This is a very contagious virus, but the infection usually passes within a couple of days. Norovirus is responsible for the typical gastroenteritis seen in adults and older children. The oro-fecal route transmits it, but it can also be transferred from one person to another.
  • Adenovirus – This is another common cause of gastroenteritis in young children. It is the second most common cause of gastroenteritis in children under two years of age. It can infect at any time during a given year.
  • Astrovirus: It can infect people of all ages, mainly affecting babies and young children. It is more common in winter, although it is found all year round.

Viral infections can be seasonal, which means that they occur more frequently.

For example, more people get norovirus infections during the winter and spring. In babies, diapers are a significant source of infection.

Germs from feces can contaminate the child’s hands and parents’ hands.

Viruses cause disease by infecting or irritating the cells of the inner lining of the small intestine, causing fluids, salts, and minerals to be expelled through the intestines in the form of diarrhea.


Food poisoning occurs when a person consumes food contaminated with bacteria that can cause gastroenteritis.

The symptoms associated with food poisoning are caused by the bacteria themselves or by the derived substances (toxins) that they produce.

Food poisoning symptoms can appear within hours or days of eating contaminated food, depending on whether bacteria or a toxin causes the problem.

Bacteria that can cause gastroenteritis are usually caught by eating contaminated food.

The bacteria that cause food poisoning include Salmonella, Shigella, Clostridium difficile, Campylobacter, and Escherichia coli.

Contamination is usually caused by eating raw or undercooked foods, such as raw meat or unpasteurized milk.

Bacteria can cause gastroenteritis and directly infect the stomach and intestine lining.

  • Salmonella contamination is caused by ingestion of bacteria in food and by handling contaminated birds or reptiles.
  • Campylobacter contamination is caused by eating raw or undercooked poultry or cross-contamination with other foods.
  • Shigella bacteria are present in the diarrheal feces of infected individuals when they are sick or by eating contaminated food or contaminated drinking water, among others.
  • Clostridium difficile: is a bacteria that can grow in the large intestine after a person has been on antibiotics for an infection and cause gastroenteritis. The main risk factors for Clostridium difficile infection are hospitalized patients and being 65 years of age or older.


Parasites rarely cause gastroenteritis.

These tiny organisms are less responsible for intestinal irritation and gastroenteritis. For example, a person can be infected with one of these parasites by drinking contaminated water.

Swimming pools are considered standard places of contamination by these types of pests.

You can get an infection in different ways. These include:

  • I eat raw, undercooked, or contaminated foods, such as meat, seafood, or unpasteurized milk.
  • We are getting contaminated by other people by infected particles in the air or by touching infected surfaces.
  • They are drinking contaminated water, particularly in countries that lack potable water.
  • You are touching an infected animal.

If you take antibiotics, you are also more likely to have diarrhea.

This is because antibiotics can upset the natural balance of bacteria in the gut, allowing infection to break out.

Antibiotics can also sometimes directly cause diarrhea.

People at risk

Some people are more likely to get gastroenteritis than others:

  • Young children: because their immune system is not yet fully formed, they put all objects in their mouths.
  • People who travel to Africa, Latin America, and Asia.
  • Older people because their immune system is weakened.
  • People work in closed and crowded places like hospitals, summer camps, and daycare centers.

Symptoms and complications

Most people infected with these viruses have no symptoms, as almost half of them are already immunized against them.

The actual rate of infection with these viruses is much higher than indicated by the number of cases of gastroenteritis.

Every once in a while, an adult will get an infection severe enough to be a nuisance.

Young children are much more likely to be affected by these symptoms.

In adults, norovirus, when accompanied by symptoms, causes the “24-hour gastrointestinal” disease that affects adults.

Vomiting and diarrhea are two of the symptoms associated with this condition.

Stools are often soft and watery, but they usually do not contain blood or mucus.

Other symptoms may also be present, such as fever, abdominal cramps, muscle aches, and headache.

Rotavirus and norovirus tend to produce their first symptoms 1 to 3 days after infection.

Most people recover in 2-3 days without long-term severe health consequences.

Young children infected with rotavirus may experience severe watery diarrhea for a week; this is likely to cause dehydration.

Rotavirus can also cause vomiting and a high fever. In young children, adenoviruses can cause diarrhea for up to 2 weeks.

In some cases, it is accompanied by mild vomiting and a low fever. Symptoms can occur only a week after the time of infection.

Astroviruses can cause rotavirus-like symptoms with mild infection.

Symptoms associated with food poisoning often include nausea, general weakness or exhaustion, headache, cramps, or other abdominal pain that causes sudden vomiting and diarrhea.

If symptoms last more than 48 hours, the doctor may want to do a blood or stool test and determine what foods are involved.

In young children, the appearance of fever accompanied by diarrhea or vomiting warrants a medical consultation.

Adults don’t have to visit the doctor unless the severity of vomiting or diarrhea warrants it or other significant illnesses present.

Because the symptoms usually go away on their own. On the other hand, if severe diarrhea or vomiting persists for more than two days, consult your doctor.

Your doctor should also be consulted if the following symptoms occur:

  • The presence of blood in vomit or stool.
  • The stiff, swollen, and painful abdomen.
  • High fever.
  • Shaking chills.
  • Excessive thirst, dry mouth.
  • Excessive lethargy
  • Dizziness or lightheadedness when changing positions (for example, getting up from a sitting place).


In adults and older children, symptoms are highly suggestive of viral gastroenteritis.

Stool tests are sometimes done under certain circumstances where the doctor suspects another cause, such as food poisoning.

In the case of food poisoning, it is essential to identify the source of contamination with certainty to prevent other people from getting sick from the water or food involved.

Children under one year of age should be monitored and treated by a doctor.

Patients who vomit for several hours and have a fever should also be subject to medical treatment.

The diagnostic methods are:

  • History taking into account the patient’s symptoms.
  • Eventually, a fecal examination must be done to identify the pathogen.
  • Blood and urine tests are done to determine the degree of dehydration.


The essential point is to replace the lost fluids.

To avoid dehydration, it is necessary to drink 2 to 3 liters per day. Recommended drinks are water, tea, fruit juices, highly diluted soup, and boiled rice.

Soft drinks should be avoided, except for cola, which can be consumed moderately from time to time.

Babies, the elderly, or patients who do not keep the fluid should receive medical treatment.

Antibiotics are generally not prescribed until a bacterium or parasite has been identified as the cause of the infection.

Antibiotics may be recommended if the infection is due to certain bacteria, especially Campylobacter and Shigella, if laboratory tests have adequately identified them.

Otherwise, an antibiotic can aggravate certain infections or make them last longer. Some diseases, such as salmonella, are not treated with antibiotics.

For adults, the doctor may prescribe medicine to stop vomiting. Sometimes these drugs are defined as a suppository.

Doctors do not usually prescribe antiemetics for children, but older children may be prescribed an antiemetic (anti-nausea) at a low dose, depending on the situation.

Finally, anti-diarrhea medications are generally not recommended if the infection is associated with a toxin that causes diarrhea.


Washing your hands frequently is the best way to protect yourself from the virus, as exposure to the virus, even in low concentrations, is enough to cause illness.

In addition, the virus can survive for a long time on objects and surfaces (such as sinks, toilets, and doorknobs) and food, sometimes up to 12 days.

Wash hands before and after contact with food or utensils, after caring for a sick person, changing diapers, handling garbage, using the telephone, shaking hands, playing with pets, or going to the bathroom.

If you are infected with norovirus, you should avoid going to work or school, as it is easy to spread the virus to people you are in direct contact with.

Gastroenteritis cannot be cured, but symptoms usually go away within two days.

Dehydration should be prevented because diarrhea makes you lose fluids.

Adults can take oral rehydration solutions or broth.

For children under the age of 5, doctors generally recommend using oral rehydration solutions sold in pharmacies.

It is better not to eat anything during the first day of the illness because any food can be vomited.

Drink water or clear liquids or, if they cannot be tolerated, suck on ice cubes. You can also consume a clear soup, bananas, soup, crackers, rice, and oatmeal.

Follow a mild, non-irritating diet until you return to normal.

Probiotics and gastroenteritis

Probiotics are “good” bacteria found in certain foods (such as live yogurts) and food supplements.

Some probiotics can aid in recovery from diarrhea, but more research is needed before we can be sure.

All bacteria are often considered harmful and cause disease, but many beneficial bacteria can help keep your gut healthy.

Some bacteria in the gut help prevent harmful organisms from growing.

Gastroenteritis is usually caused by harmful bacteria, viruses, or parasites.

Probiotic bacteria like Lactobacillus may help correct the balance of bacteria in the gut.

These bacteria can relieve symptoms of diarrhea and speed recovery.

They may also help prevent gastroenteritis, such as traveler’s diarrhea.