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Gastroenteritis (Stomach Flu)


Gastroenteritis, commonly known as Stomach Flu or Stomach bug, is inflammation of the stomach and intestines. It is characterized by diarrhea and vomiting. Causative organisms may be viruses, bacteria, or parasites. It spreads through contaminated food, water, and shared items. The disease usually lasts for a week or two and resolves on its own depending on the causative organism. Treatment involves the symptomatic treatment, but antibiotics may be required in bacterial gastroenteritis.


The cause of gastroenteritis depends on infectious agents, such as bacteria, viruses, parasites, fungi. The most common organisms are:
▪ E. Coli
▪ Salmonella
▪ Campylobacter

Some parasites can cause gastroenteritis, of which Giardia lamblia is most common, followed by Entamoeba histolytica and Cryptosporidium spp.


It can be classified into viral and bacterial gastroenteritis.

Viral Gastroenteritis: Globally, It is the most common form of gastroenteritis affecting people of all ages, colors, and races. Rotavirus, Norovirus, and Adenovirus are the most common viruses that cause gastroenteritis. It usually spreads through the Oro-fecal route, meaning if the infected person does not wash their hands properly after using the toilet and serves you food or if you use his towel, you can get sick. Viral gastroenteritis is more of concern in children and older adults because of their weak immune systems.

Bacterial Gastroenteritis: When a bacterium causes stomach flu (gastroenteritis), it is called bacterial gastroenteritis. It is less common than viral gastroenteritis but still poses a great health risk because of dehydration.

Signs And Symptoms

Viral Gastroenteritis

1. Watery diarrhea
2. Nausea
3. Vomiting
4. Abdominal cramps (stomach pain, belly cramps)
5. Low-grade Fever
6. Lethargy, weakness
7. Dehydration, look for signs of dehydration which include dry and sunken eyes, dry tongue, dry
skin, dark urine)
8. Drowsiness, mentally confused

Bacterial Gastroenteritis

1. Diarrhea, which can be bloody
2. Nausea
3. Vomiting
4. High-grade fever
5. Abdominal cramps
6. Dehydration
7. Lethargy
8. Drowsiness


Your healthcare provider will diagnose your illness by taking a careful history. No lab tests are required to diagnose viral gastroenteritis. Bacterial gastroenteritis is diagnosed by careful history and some laboratory tests to confirm the diagnosis. These include blood tests to see the severity of the disease and stool tests to confirm the causative microorganism.


Treatment usually involves supportive and symptomatic care. The mainstay of treatment in all types of gastroenteritis is to prevent dehydration. Symptomatic treatment is given for fever and or if the pain is unbearable. Depending on the severity of the disease, IV fluids are also advised if the patient cannot take anything by mouth.
Avoiding dehydration is very important. Try drinking as much liquid as you can. Drink in small sips if you are not able to keep fluids down. You can take any fluids you like. It can be an oral rehydration solution or green tea or juice but avoid sugary juices that worsen diarrhea. 
Solids should be introduced slowly and gradually. Initially, soft food should be given. The BRAT diet is commonly prescribed. It includes banana, rice, applesauce, and toast.

In bacterial gastroenteritis, antibiotics are given to combat the causative organism. Gastroenteritis in Infants and elderly: Though stomach flu is bothersome for people of all ages, it is particularly dangerous in infants and older adults. In infants, their immune system is not mature enough and in seniors’ immune system is weak, making them an easy and vulnerable target for microorganisms.
A close eye should be kept on signs of dehydration in both populations when they get sick. In infants, signs of dehydration include; Less number of wet diapers than normal Spitting up should not be confused with throwing up
Highly irritable and crying In pain and discomfort Crying without tears Look for the soft spot on child’s head (fontanelle) if it feels sunken it is an alarming sign Abdominal breathing Dry skin and tongue Is sleepy or unresponsive
Similarly, dehydration is the major risk factor in elderly patients. It should be addressed promptly to avoid any further complications. Patients can go in shock, and death can occur if dehydration is not treated promptly. Adults' dehydration may look like:

  • Unstable mental status
  • Little or no urination
  • Dark urine, which may appear bloody
  • Skin looks dry and crackly
  • Dry tongue
  • Sunken eyes
  • Transmission

Gastroenteritis is a highly transmissible disease. Viral gastroenteritis usually spreads through the orofecal route (the germs spread through infected person’s feces, dirty hands, utensils, and towels), while bacteria gastroenteritis is caused by undercooked food.

Differential Diagnosis

Some conditions can cause signs and symptoms similar to gastroenteritis like;


Despite its high transmissibility, it can be easily prevented by following simple hygiene rules:

  • Frequent hand washing
  • Avoid contact with an infected person
  • Don’t share utensils and towels
  • Disinfect hard surfaces, doorknobs, faucets, switch lights.
  • Vaccinate your child
  • Don’t send the child to school if they are sick.

Vaccine:  Vaccine against rotavirus is available in many countries. It is given in the first year of life to protect the child against severe complications of gastroenteritis.
Traveler’s Diarrhea: It is very common for people to travel from developed countries to developing countries. It is similar to gastroenteritis described above and can easily be prevented by avoiding eating uncooked, raw food like salads, fruits, unhygienic street foods, drinking tap water, or juices from stalls.

Our clinical experts continually monitor the health and medical content posted on CURA4U, and we update our blogs and articles when new information becomes available. Last reviewed by Dr.Saad Zia on May 06, 2023.




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