Acute gastroenteritis

Overview

Acute gastroenteritis is inflammation of the stomach and intestines, usually from an infection. It causes diarrhea, vomiting, nausea and abdominal cramps, sometimes with fever. Most cases pass on their own within 1–3 days.

The popular name “stomach flu” is inaccurate: the illness is not caused by the influenza virus.

Causes and how it spreads

• Viruses — norovirus is the most common cause in adults; rotavirus in young children, especially the unvaccinated.
• Bacteria — Salmonella, Campylobacter, some types of E. coli, often from contaminated food.
• Parasites — e.g. Giardia, with longer-lasting symptoms.

The infection spreads through contaminated food or water, from surfaces, or by direct contact with the sick person. Washing hands with soap and water is the most effective measure (alcohol gel does not eliminate norovirus well).

Diagnosis

Most cases are diagnosed by the doctor without tests. Tests (stool culture, tests for viruses or parasites, electrolytes and kidney function) are ordered when there is blood in the stool, severe illness, prolonged symptoms or risk factors.

Treatment

Fluids are the main treatment.

• Use an oral rehydration solution (ORS) in small, frequent sips, even if you are vomiting.
• Limit very sweet and fizzy drinks — they can make diarrhea worse.
• Go back to your usual food as soon as you have an appetite. The restrictive “BRAT” diet (bananas, rice, applesauce, toast) is no longer recommended as standard treatment.
• Infants continue breastfeeding or their usual formula.

Antibiotics are not used routinely. Even when a bacterium is found in a stool culture, this does not automatically mean an antibiotic is needed; in some infections antibiotics can be harmful. Anti-diarrheal medicines are used only when they are appropriate for the age and situation.

When to seek help

Seek medical assessment if symptoms last more than a few days or get worse. Infants, pregnant women, the elderly and people with weakened immunity should be seen sooner.