turgor, skin color discoloration, sunken fontanelles, sunken eyeballs, darkened eye circles, glassy eyes, poor perfusion and ultimately shock.

Symptoms occur for up to 6 days on average. Given appropriate treatment, bowel movements will return to normal within a week after that.

Laboratory tests

Examination of stool for toxins, (e.g. Clostridium difficile toxin)

Stool cultures for the organisms that causes the disease, (e.g. Salmonella, Shigella, Campylobacter and enterotoxic Escherichia coli)

Microscopy for parasites and their ova and cysts

ELISA for viruses

Infectious

Infectious gastroenteritis is caused by a wide variety of bacteria and viruses.

Bacterial

For a list of bacteria causing gastroenteritis, see above. Pseudomembranous colitis is an important cause of diarrhea in patients often recently treated with antibiotics. Viruses causing gastroenteritis include rotavirus, norovirus, adenovirus and astrovirus.

If gastroenteritis in a child is severe enough to require admission to a hospital, then it is important to distinguish between bacterial and viral infections. Bacteria, Shigella and Campylobacter, for example, and parasites like Giardia can be treated with antibiotics.

Viral

Viruses do not respond to antibiotics and infected children usually make a full recovery after a few days.[Children admitted to hospital with gastroenteritis routinely are tested for rotavirus A to gather surveillance data relevant to the epidemiological effects of rotavirus vaccination programs.]These children are routinely tested also for norovirus, which is extraordinarily infectious and requires special isolation procedures to avoid transmission to other patients. Other methods, electron microscopy and polyacrylamide gel electrophoresis, are used in research laboratories.

Management

The objective of treatment is to replace lost fluids and electrolytes. Oral rehydration is the preferred treatment of fluid and electrolyte losses caused by diarrhea in children with mild to moderate dehydration.

Rehydration

The principal treatment of gastroenteritis in both children and adults is rehydration, i.e., replenishment of water lost in the stools. Depending on the degree of dehydration, this can be done by giving the person oral rehydration therapy (ORT) or through intravenous delivery.

People taking diuretics ("water pills") need to be cautious with diarrhea and may need to stop taking the medication during an acute episode, as directed by the health care provider.

Dietary therapy

Centers for Disease Control and Prevention recommendations for infants and children include:

Breastfed infants should continue to be nursed on demand.

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