Gastroenteritis

Gastroenteritis can be infectious and spread in many ways, including contact with an infected person or animal, contaminated food, water, or objects, and not washing your hands after going to the toilet or changing a nappy. Gastroenteritis can be caused by viruses, bacteria, bacterial toxins and parasites.

Some of the bacteria that cause gastroenteritis are found in human or animal faeces and uncooked or undercooked meat, especially chicken and seafood.

Causes of infectious gastroenteritis can include

• Bacteria such as Staphylococcus, Salmonella, Campylobacter, Shigella, and E. coli
• Viruses such as norovirus, rotavirus and adenovirus
• Toxins produced by bacteria, such as some strains of staphylococcal bacteria
• Parasites such as Cryptosporidium, Entamoeba and Giardia.

Gastroenteritis may also be non-infectious and caused by

• Medication, such as antibiotics, which may upset the balance of the microbiome in some people
• Chemicals, such as lead, and poisons found in some mushrooms.

Gastroenteritis is common globally, particularly in developing countries where people may not have access to clean water.

Food premises with inadequate hygiene practices can also put their patrons at risk which can lead to outbreaks in large institutions such as hospitals, nursing homes and schools.

People who may be more susceptible to severe gastroenteritis include

• Infants and young children with immature immune systems
• Older adults, particularly those in aged care facilities
• People with compromised immune systems
• School children, boarders and other groups who share close quarters.

Some of the most common types of infectious gastroenteritis caused by bacteria or viruses include

• Escherichia coli infection
  • E. coli bacteria usually live in the intestines of healthy people, but some strains can cause severe stomach, cramps, diarrhoea and vomiting, Some strains can cause an acute type of kidney failure known as the haemolytic uraemic syndrome (HUS).
• Salmonella infection (Salmonellosis)
  • A common food-related cause of gastroenteritis, referred to as ‘food poisoning’. The risk is higher in areas with poor sanitation.
• Campylobacter infection (campylobacteriosis)
  • One of the most common forms of bacterial gastroenteritis caused by ingesting raw or undercooked poultry, contaminated water, or unpasteurised milk.
• Shigella infection (Shigellosis or bacterial dysentery)
  • Shigella is very infectious, and only a small number of bacteria are needed to become ill. This is mostly spread by faecal contamination with young children and elderly most at risk.
• Viral gastroenteritis

• Highly infectious noroviruses are the most common cause of foodborne illness globally, and rotavirus is the most common cause of viral gastroenteritis in children.

People with gastroenteritis can develop a range of symptoms, that may take from one to three days to develop and may last up to 10 days in severe cases.

Symptoms are similar in viral and bacterial gastroenteritis, which can make them difficult to distinguish. The most common symptom is dehydration.

Other symptoms may include

• Diarrhoea
• Nausea
• Vomiting
• Fever
• Stomach cramping and pain
• Bloating
• Lethargy
• Headache
• Dizziness or light-headedness
• Body aches
• Loss of appetite
• Electrolyte imbalance
• Blood and/or pus in stools
• Sunken eyes
• Dry mouth or tongue
• Muscle cramps
• Reduced urine production
• Weakness
• Irritability.

Fluids can be rapidly lost due to vomiting and diarrhoea, requiring intravenous replacement in severe cases. Severe dehydration is a medical emergency and requires urgent treatment. Dangerous symptoms in adults can include

• Confusion
• Weakness
• Producing very little urine
• Rapid heart rate
• Coma.

All babies aged under six months should be checked by a medical practitioner for dehydration. Children and adults should see a doctor if symptoms are severe, or they have underlying health conditions.

Viral and bacterial gastroenteritis have similar symptoms. Mild cases may not require diagnosis, but if the illness is more severe or persistent, a stool (faecal) sample and/or blood test may be required to investigate the cause and to determine whether treatment is required and/or possible.

Standard treatments for gastroenteritis include

• Drinking fluids, including water and rehydration drinks found at pharmacies. Patients should sip regularly, even if they are vomiting, to avoid dehydration
• Rest at home from school or work particularly if infectious
• Paracetamol for any fever
• Antibiotics, if caused by bacteria
• Anti-parasitic drugs, if caused by parasites
• Hospital admission and an intravenous drip in severe cases.

While many people with gastroenteritis will not require medication, some types of gastroenteritis can be life-threatening for vulnerable members of the community. In addition, the evolution of new superbugs is leading to current treatments becoming ineffective. The development of new antibiotics is urgently needed to combat the rise in antimicrobial resistance.

New vaccines against gastrointestinal infections are especially needed in developing countries where gastroenteritis is a leading cause of illness and death, particularly for infants, children and the elderly.

To prevent gastroenteritis, it is important to

• Wash hands thoroughly with soap and water, especially before food preparation
• Always wash hands after going to the toilet, changing a nappy or touching animals,
• Stay home while sick to avoid infecting others
• Observe good food preparation hygiene
• Avoid raw food that may have been exposed to contaminated surfaces
• Avoid undercooked meat and fish
• Avoid sharing eating utensils
• Keep toys and kitchen and bathroom surfaces clean
• Drink bottled water and avoid ice cubes in countries without access to clean potable water.