Gastroenteritis

Gastroenteritis is a short-term illness caused by infection and inflammation of the digestive system. Typical symptoms include abdominal cramps, diarrhea, and vomiting. In many cases the condition clears up on its own within a few days.

The main complication of gastroenteritis is dehydration, but this can be prevented by replacing the fluid lost through vomiting and diarrhea. A person with severe gastroenteritis may need fluids given intravenously (directly into the bloodstream through a vein, using a setup often called a “drip”).

Symptoms#

Symptoms of gastroenteritis can include:

• loss of appetite
• bloating
• nausea
• vomiting
• abdominal cramps and abdominal pain
• diarrhea
• generally feeling unwell, including lethargy and body aches
• in some cases, blood or pus in the stools

Causes#

There are many things that can cause gastroenteritis, including viruses, bacteria, bacterial toxins, parasites, certain chemicals, and some medicines. The main causes include:

• viruses – such as norovirus, calicivirus, rotavirus, astrovirus, and adenovirus
• bacteria – such as Campylobacter
• bacterial toxins – in some cases the bacteria themselves do not cause illness, but their poisonous by-products can contaminate food. Some strains of staphylococcal bacteria, for example, produce toxins that can cause gastroenteritis
• parasites – such as Entamoeba histolytica, Giardia lamblia, and Cryptosporidium
• chemicals – lead poisoning, for example, can trigger gastroenteritis
• medication – certain medicines, such as some antibiotics, can cause gastroenteritis in susceptible people

Infectious gastroenteritis#

Infectious gastroenteritis is caused by viruses, bacteria, or parasites. In each case, infection occurs when the agent is swallowed, usually through eating or drinking. Common types include:

• Escherichia coli infection – these bacteria are found in animal feces. Infection can occur from eating contaminated food or undercooked meat (especially poultry), or from not washing your hands after handling infected animals
• Campylobacter infection – these bacteria are found in animal feces. Infection can occur from eating contaminated food or handling infected animals. An infected person may spread the bacteria to others or to surfaces by not washing their hands properly
• Cryptosporidium infection – these parasites are found in the bowels of humans and animals. Infection can occur from swimming in a contaminated pool and accidentally swallowing water, or through contact with infected animals
• Giardiasis – a parasite infection of the bowel. Infection can occur from drinking contaminated water, handling infected animals, or changing the diaper of an infected baby and not washing your hands afterwards
• Salmonellosis – these bacteria are found in animal feces. Infection can occur from eating contaminated food or handling infected animals
• Shigellosis – these bacteria are found in human feces. An infected person may spread the bacteria to food or surfaces if they do not wash their hands after going to the toilet
• Viral gastroenteritis – infection is spread by person-to-person contact, such as touching contaminated hands, feces, or vomit, or by consuming contaminated water or food

An infected person can spread germs to food or surfaces if they do not wash their hands after going to the toilet.

Diagnosis#

It is important to establish the cause, because different types of gastroenteritis respond to different treatments. Diagnosis may involve:

• medical history
• physical examination
• blood tests
• stool tests

Treatment#

Treatment depends on the cause, but may include:

• plenty of fluids
• oral rehydration drinks, available from your pharmacist
• admission to hospital and intravenous fluid replacement, in severe cases
• antibiotics, if bacteria are the cause
• medicines to kill the parasites, if parasites are the cause

Avoid anti-vomiting and anti-diarrhea drugs unless they are prescribed or recommended by your doctor, because these medicines can keep the infection inside your body.

Prevention#

Gastroenteritis is highly contagious. Good handwashing with soap and water remains the best defense against spreading the bug. General suggestions to reduce the risk of infection include the following.

• Stay home while sick, and ideally until 48 hours after symptoms have stopped. If symptoms persist, visit your doctor.
• Wash your hands thoroughly with soap and water after going to the toilet or changing diapers, after smoking, after using a tissue or handkerchief, and after handling animals.
• Wash your hands thoroughly with soap and water before preparing food or eating.
• Use disposable paper towels to dry your hands rather than cloth towels, because germs can survive for some time on objects.
• Do not handle raw and cooked foods with the same implements (tongs, knives, cutting boards) unless they have been thoroughly washed between uses.
• Keep all kitchen surfaces and equipment clean.
• Keep cold food cold (below 5°C / 41°F) and hot food hot (above 60°C / 140°F) to discourage the growth of bacteria.
• Make sure foods are thoroughly cooked.
• Clean kitchen tops, toys, toilet seats, diaper change tables, and taps regularly so you do not spread the infection to others at home.
• Clean the toilet and bathroom regularly, especially the toilet seat, door handles, and taps.

When traveling to places where sanitation may be unreliable, drink only bottled water, and use bottled water to brush your teeth. Avoid food buffets, uncooked foods, peeled fruits and vegetables, and ice in drinks.

Note: washing your hands with soap and water is the best way to prevent infection. Alcohol-based hand sanitizers, while effective against some viruses, are not effective against the germs that commonly cause gastroenteritis.

Key points#

• Typical symptoms include abdominal cramps, diarrhea, and vomiting.
• Symptoms can also include generally feeling unwell, with lethargy and body aches.
• Infectious gastroenteritis is caused by viruses, bacteria, or parasites.
• Infection often spreads through contaminated food or water, or through contact with infected animals or people.
• The main risk is dehydration, which can be prevented by replacing lost fluids.

Where to get help and trusted information#

For evidence-based global health guidance, see Source: World Health Organization (WHO).