Gastroenteritis refers to vomiting and diarrhoea. The cause is usually viral and it represents one of the most common reasons for seeing a doctor. The treatment involves oral rehydration therapy to avoid dehydration.


What causes gastroenteritis?shutterstock_113785489

In most instances viruses caught from other children or adults will cause vomiting and diarrhoea. Bacteria can also be responsible such as salmonella, campylobacter, and E.Coli. Generally bacterial infections are caught from contaminated food which has not been refigerated or prepared properly.  Parasites such as giardia are also common and are generally the only organism that requires specific treatment. This parasite can be caught in daycares, but is also found in contaminated water such as water tanks, streams, (camping holidays) and lakes.

What are the symptoms?

Usually the illness will commence with vomiting, fever, and abdominal pains, followed by diarrhoea. The vomiting will last 24 – 72 hours, and this is the most dangerous period for dehydration. Diarrhoea will be present for 3-7 days but the bowel action may take several weeks to recover. Intermittent abdominal pains prior to the diarrhoea are also common. In viral infections there maybe a runny nose, slight cough at the same time.
In bacterial infections the symptoms are generally more severe. The fever, abdominal pains are can be quite distressing and sometimes there is blood and mucus in the bowel actions.
Giardia tends to be a milder illness, with abdominal pains and loose bowel actions and loss of appetite the primary symptoms.

All causes are contagious, and can spread through families, daycare centres and even hospital waiting rooms!

What is the treatment? shutterstock_219725935

The mainstay of treatment is to avoid dehydration by ensuring oral rehydration therapy as outlined below. In some instances a medication called ondansetron (zofran) is given as a wafer. This has been shown to lessen vomiting, and is safe in infants and children, though should be used strictly as directed.

Antibiotics should not be used unless giardia or another parasite is detected in stool samples. In this instance metronidazole 30mg/kg given once daily for three days should be used. For bacterial infections such as salmonella there is no place for using antibiotics unless serious infection is suspected. Antibiotics have been shown to worsen diarrhoea.

How can you tell if your child is dehydrated? 

The signs of dehydration in the infant and toddler can be difficult. With profuse vomiting an infant can quickly become dehydrated. In the early stages dehydration is recognised by thirst, less activity and less urination.  It is at this point that fluids need to be frequently offered. If dehydration progresses there will be lethargy, dryness of mouth, coolness of hands and feet, sunken eyes and the skin will appear ‘loose’.  By this stage hospitalisation is recommended.

How to treat Dehydration

Oral rehydration therapy involves giving frequent small amounts of appropriate water, electrolytes, and sugar. Examples include hydrolyte and gastrolyte. If unable to obtain these mix one litre of water with half teaspoon of sugar, four teaspoons of salt and if possible half a cup of orange juice or some mashed banana to improve the taste.

Water is a reasonable first option but will not replenish lost electrolytes and this can sometimes cause low sodium which is potentially serious. Flat lemonade, milk, lucozade, other soft drinks are not recommended.

Infants with mild dehydration

shutterstock_165430145Continue to breast feed and if there is vomiting offer oral rehydration therapy (ORT). With formula fed infants just use ORT. Do not use solids while there is vomiting. The mainstay of therapy in the vomiting infant is to administer small amounts of fluid frequently. Therapy should be initiated with 5ml lots given every 1 to 2 minutes.  Aim for about 100-150 mls per hour.  (10-20mls/kg/hr). A syringe is useful. Although this technique is labor intensive it can be done by a parent and will deliver 150 to 300 ml/hour. As the vomiting lessens, larger amounts of ORT can be given after longer intervals. Once rehydration is accomplished, other fluids including milk and age appropriate foods can be introduced. If the vomiting continues despite efforts to administer fluids hospital is required.

Toddlers and Children with mild dehydration

Use the ORT as described. Many children will not like the taste. If this is a problem, use dilute apple juice as an alternative. Aim for 150-250mls per hour depending on age and size. (10-20mls/kg/hr). Give this in small amounts frequently.  As the vomiting eases then start age appropriate foods including complex carbohydrates (rice, potatoes, bread and cereals), lean meats, yogurt, fruits and vegetables. Foods to be avoided include fatty foods or foods high in simple sugars (juices and soft drinks).

How should children be managed who have diarrhoea but are not dehydrated?

These children should continue to be fed age appropriate diets. Several studies have now demonstrated that unrestricted diets shorten the time a child has diarrhoea. There is no need for ORT if the child is not dehydrated. There has been some recent information that lactobacillus and acidophilus shorten the duration. These are called probiotics and are found in health food stores.

What about Lactose intolerance ?

Some infants will develop ongoing diarrhoea, which can be frothy, explosive and persist far longer than expected. Often there is an associated nappy rash. This can sometimes be due to a temporary intolerance to lactose. The intestine is slightly damaged by infectious diarrhoea and cannot breakdown lactose. It will then be fermented in the large intestine resulting in explosive diarrhoea. limiting lactose by temporarily moving to a lactose free formula such as a soy based formula will quickly fix this.

What happens in hospital ?

Once the diagnosis is confirmed on history and examination treatment is one of three options. Continue oral re-hydration, place a tube onto the stomach through the nose (nasogastric) or replace fluids with an iv. (rare).  Generally fluid replacement is 50-100mls per kg given over 3 -4 hours.

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