Gastroenteritis, also commonly known as stomach flu, is caused when the lining of one’s intestine gets inflamed. This can happen due to two reasons: viral infection and bacterial infection. One can get this infection from another person who has the flu, surfaces that have been in contact with these viruses and bacteria, or foods that contain these germs. Moreover, the infection progresses through different stages and lasts about two weeks.

Causes of stomach flu
The chances of having stomach flu are high when one accidentally consumes contaminated foods or beverages, especially water. Further, one may be infected if one has touched or shared food, towels, or cutlery with another person who has one of the viruses or bacteria that cause gastroenteritis.

These are some of the viruses and bacteria that can cause stomach flu.

• Noroviruses
  This virus is one of the most common causes of foodborne health disorders. It affects children as well as adults. Also, it is highly contagious since it is known to affect every member of a family if any one among them is infected.
• Rotavirus
  This virus generally spreads among small children, it may also affect infants. The symptoms can be quite severe and last a few days. Some adults may also get stomach flu from rotavirus. But the symptoms do not usually show up.
• Adenovirus
  Children under two years old usually get stomach flu from this virus. The symptoms can last from 5 to 12 days.
• Astrovirus
  This virus too generally infects infants and young children to cause stomach flu. It usually spreads through contaminated water and food.
• Bacteria
  Salmonella, campylobacter, shigella, Escherichia coli (E. coli), and Clostridium difficile (C. difficile) are some of the common bacteria that cause stomach flu. The infection spreads through food and water that contains these bacteria.
• Parasites
  Giardia and cryptosporidium are two parasites that thrive in water. Drinking such contaminated water or swimming in it may cause parasitic infection, leading to stomach flu.

Risk factors
Gastroenteritis or stomach flu is generally observed among the following age groups:

• Young children who are in child care centers or elementary schools
• Older adults, especially those in nursing homes

Other groups that are at the risk of stomach flu include:

• People who live in close quarters such as dormitories
• Those with weak immune systems due to any health disorder

Signs and symptoms
Stomach flu directly affects the intestines. The symptoms start to appear one to three days after exposure to the virus, bacteria, or parasite. In most cases, these signs of stomach flu can last a couple of days; however, severe infection may last about 14 days.

• Watery and non-bloody diarrhea
• Nausea
• Vomiting
• Abdominal pain and cramps
• Headache
• Muscle ache
• Fever, which is usually low grade

The above symptoms usually go away on their own in a couple of days. However, it is important to consult a doctor as soon as possible if one starts experiencing any of the following symptoms.

• Inability to keep any liquids down for over 24 hours
• Diarrhea, nausea, or vomiting for more than a couple of days
• Vomiting blood
• Experiencing symptoms of dehydration such as dry mouth, excessive thirst, deep yellow urine, severe weakness and dizziness
• Noticing blood in stool
• Severe abdominal pain
• Fever that is above 104 F

Management options
In the case of mild symptoms, there are generally no treatments that are prescribed. It usually involves taking the following measures until the symptoms go away:

• Stay hydrated
  Diarrhea and vomiting cause a lot of fluid loss, leading to severe dehydration that can worsen the stomach flu symptoms. It can also cause other health complications. So, it is important to stay hydrated. Oral rehydration solutions, electrolyte solutions, fresh coconut water, soups, and so on can help one stay hydrated. However, these should be had in small amounts frequently throughout the day.
• Eat bland and semi-liquid or liquid foods
  Since stomach flu happens in the intestine, it affects the digestive system. Therefore, one must avoid having foods that are difficult to digest. These include raw fruits and vegetables, spicy foods, solid foods, any type of meat, dairy products, or packaged snacks. Bland foods that have been blended, pureed, or made into soups are safe to have during a stomach flu.
• Avoid caffeine
  Coffee, tea, and other beverages that have high amounts of caffeine affect the digestive system. These can worsen diarrhea and stomach cramps. Whether it is cold coffee, milk tea, energy drinks, or black coffee, these need to be avoided until the stomach flu signs go away.
• Have ginger and peppermint
  Instead of caffeinated beverages, have tea made with ginger and peppermint. These ingredients soothe the digestive system. Furthermore, these help to manage inflammation, giving relief from vomiting and nausea. In addition, the tea can help in dealing with dehydration.

In case the signs of stomach flu remain for more than two days, it is recommended to consult a doctor immediately and seek prescribed treatment options.