What is Viral Gastroenteritis (also known as "gastric flu")?

Gastroenteritis means inflammation of the stomach and intestines. It can be caused by:

• infection by certain bacteria, viruses or parasites, or;
• certain medications or medical conditions

Viral gastroenteritis can be caused by many different viruses. It is sometimes called “gastric flu” although it is not related to influenza. Some of the viruses that can cause gastroenteritis include rotaviruses, noroviruses, adenoviruses, sapoviruses and astroviruses.

Symptoms

May include:

• diarrhoea
• vomiting (throwing up)
• nausea
• stomach pain/cramps
• fever
• headache
• body aches

A person usually develops symptoms 12 to 48 hours after exposure to the virus. Most people get better within 1 to 3 days. In general, children experience more vomiting than adults. Low-grade fever may be present. 
If you have gastric flu, you can feel extremely ill and vomit or have diarrhoea many times a day, which can lead to dehydration, especially in young children, older adults, and people with other illnesses.

Symptoms of dehydration:

• decrease in urination
• dry mouth and throat
• lethargy
• feeling dizzy when standing up
• constipation

Children who are dehydrated may cry with few or no tears or be unusually sleepy or irritable.


How Gastric Flu Spreads

The viruses that cause gastroenteritis are spread in several ways, including:

• Eating or drinking contaminated foods or liquids.
• Touching contaminated surfaces or objects, then placing the hand in the mouth.
• Direct contact with another person who is infected and showing symptoms (e.g, caring for someone with the illness, or sharing foods or eating utensils with someone who is ill).

Viruses that cause gastroenteritis, such as norovirus, can spread quickly in closed places like childcare and daycare centers, nursing homes, schools, and cruise ships. They are often highly contagious. Anyone can get infected and become sick. You can also get gastric flu many times in your life. One reason for this is that there are many different types of viruses. Being infected with one type of virus may not protect you against other types. Viruses may be found in your stool (faeces) even before you start feeling unwell. They can stay in your stool for 2 weeks or more after you feel better.
You are most contagious:

• when you are sick with a gastric flu illness, and;
• during the first few days after recovery 

You should not prepare food for others or provide healthcare whilst you are sick and for at least 2 days after symptoms stop. This also applies to sick workers in places such as schools and daycares where they may expose other people to the virus.
Food workers and preparers with viral gastroenteritis should also not work until at least 48 hours after symptoms stop. If you were recently sick, you can be given different duties that do not involve food handling.


Treatment

There is no specific medicine to treat people with viral gastroenteritis. It cannot be treated with antibiotics because it is a viral (not a bacterial) infection and antibiotics do not help viral infections.
Gastroenteritis is usually brief in healthy persons - the most serious health effect is dehydration. If you have norovirus illness, you should drink plenty of liquids to replace fluid lost from vomiting and diarrhoea. This will help prevent dehydration.

Sports drinks and other drinks without caffeine or alcohol can help mild dehydration. However, these drinks may not replace important nutrients and minerals. Oral rehydration fluids that you can get over the counter are most helpful. Severe dehydration may require hospitalisation for treatment with fluids given through your vein (intravenous or IV fluids). This is more common in the very young, the elderly, and persons with weakened immune systems. If you think you or someone you are caring for is severely dehydrated, seek medical attention straight away.

Precautions You Can Take

You can reduce your chance of contracting viral gastroenteritis by following these preventive steps:

• Wash your hands frequently, especially after toilet visits and changing nappies and before eating or preparing food. Alcohol-based hand sanitizers can be used in addition to hand washing. But, they should not be used as a substitute for washing with soap and water.
• Wash fruits and vegetables thoroughly before eating.
• Ensure food (especially shellfish) is thoroughly cooked before consumption.
• Clean and disinfect contaminated surfaces thoroughly immediately after an episode of illness by using a solution of 1 part bleach to 9 parts water.
• Immediately remove and wash clothing or linens that may be contaminated with virus after an episode of illness (use hot water and soap).
• Flush or discard any vomit and/or stool in the toilet and make sure that the surrounding area is kept clean.