A gastrointestinal infection or gastroenteritis is an infection of the stomach and / or intestines. Symptoms include nausea, vomiting, abdominal pain and watery diarrhoea. Fever may also occur. Symptoms can range from mild to severe. Dehydration is the most serious but rare complication.
Gastrointestinal infection usually has a viral cause, with norovirus being the most common pathogen. Other viral causatives are rotavirus and enteric adenovirus. Bacteria (S. aureus, C. jejuni, Shigella spp., Salmonella spp.), parasites (Giardia, Cryptosporidium) or bacterial toxins may also cause gastroenteritis.
The infection can be caught by eating contaminated food, drinking contaminated water or by close contact with an infected person (norovirus).
In uncomplicated cases, treatment is conservative. Faeces investigation to determine the causative agent is only advised in seriously ill patients (e.g. persistent fever), in immunocompromised patients, or when the risk of infecting others is increased (e.g. employees in the food industry or in healthcare).
Treatment involves getting enough fluids. For mild or moderate cases, this can be achieved by drinking fluids slowly, frequently and in small amounts, because drinking too much too fast can cause vomiting. Oral rehydration solution (ORS), a combination of water, salt and sugar, is used to treat moderate dehydration. It is also worth considering an interruption of diuretics and renin-angiotensin system blockers and to be attentive to hypoglycaemia in patients using blood glucose lowering medication. Dehydration may also cause increased serum levels of medication (lithium). Consider that medication absorption may be reduced. Extra attention for hygiene is recommended.
Anti-diarrhoeal medication may be helpful to relieve symptoms.
Antibiotics should only be considered in case of serious illness (e.g. persistent or high fever, rectal bleeding) or in immunocompromised patients, in addition to ORS. In these cases, antibiotics are preferably prescribed based on the culture result or possibly after consultation with a microbiologist / infectiologist. Referral is needed in patients with serious general illness, severe dehydration (confusion, increased breathing effort, severe hypotension), increased risk of a severe course or in unsuccessful attempts for rehydration. Babies younger than three months with (suspected) dehydration should be referred.