Gastric Flu (Gastroenteritis) – Symptoms, Causes, Treatment

Gastroenteritis is the  inflammation of the stomach and intestines (small and large) as a result of an infection. It is often referred to as the gastric flu or stomach flu but it is not related to influenza. Sometimes loose stool and a bit of nausea may be noticed in influenza but the gastric flu is much more pronounced. Gastroenteritis is a common infection that accounts for millions of deaths globally but with proper management, it can pass in a few days without requiring treatment.

Causes of the Gastric Flu

Gastroenteritis may be caused by many microogranisms – bacteria, viruses and protozoa. Even food poisoning is a case of gastroenteritis but the term gastric flu usually indicates an outbreak of a viral infection. Most of these viruses are transmitted by direct contact but a few can be transmitted through the air accounting for an outbreak at work or in school.

There are different types of viruses that cause gastroenteritis but the gastric flu is usually caused by the norovirus which was previously known as the Norwalk-like virus. It has an incubation period of 24 to 48 hours and the duration of the infection is from 12 to 72 hours. This can continue for longer if a person is immunocompromised (HIV/AIDS, cancer, uncontrolled diabetes).

The gastric flu is contagious and a person may spread the infection even 48 hours after their symptoms resolve. Airborne gastroenteritis is spread by droplets from coughing and sneezing, while other types of gastroenteritis may be spread by contaminated water, food or fomites (inanimate objects).

Signs and Symptoms of the Gastric Flu

  • Contact nausea
  • Vomiting and retching – sometimes blood may be present in the vomit.
  • Watery diarrhoea – sometimes blood in the stool.
  • Fever ranging from 38 to 40 degrees Celsius
  • Abdominal pain and cramps
  • Bloated abdomen

If there is inadequate rehydration, the vomiting and diarrhea can lead to dehydration. This presents as a drop in blood pressure, increased heart rate, sunken eyes, changes in skin elasticity and dizziness. Over time, heart failure and kidney failure can lead to death.

Treating the Gastric Flu

The key factor in managing a case of gastroenteritis is proper rehydration, bed rest and good nutrition. In most cases no other treatment is necessary. Antibiotics are only used in some cases of bacterial gastroenteritis and will not work for a case due to a viral cause. Medication to stop diarrhea can complicate gastroenteritis and should not be used immediately or excessively.

Gastric flu should always be taken seriously in children, particularly babies. They can quickly dehydrate and the gastric flu is one of the leading causes of death in infants throughout the world. Breastfeeding babies should not stop breast milk and it is important to boil water for bottle fed infants.

Oral rehydrating solutions (ORS) are available from pharmacies and supermarkets in sachet form. These granules can be mixed with clean water and will provide sufficient electrolytes –  sodium, potassium and chloride – to prevent dehydration and allow for a quick recovery. Home made solutions, sports drinks and carbonated soft drinks are not adequate as a rehydrating solution but may be used if there are no other options available.

Once vomiting stops, a person should attempt to eat solid foods. The BRAT diet is usually recommended initially as these foods are better tolerated. Refer to the Diarrhea Diet for more information on the BRAT diet. If normal foods can be consumed, it should be bland yet balanced, containing a healthy mix of vegetables, meat and starch to ensure sufficient protein, fat and fibre intake.

Most cases of the gastric flu will pass within 3 days and some may pass within a day. However if your gastric flu is persisting for more than 5 days, you should see a doctor immediately.