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Overview of gastroenteritis 

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Did last night’s meal at the neighborhood eatery herald a bad case of diarrhea with vomiting this morning? It’s quite likely that you have gastroenteritis.

Gastroenteritis, characterized by sudden onset of diarrhea and vomiting, is an inflammation of the lining of the stomach and the intestines (gastrointestinal tract).1 While viruses, bacteria and parasites are believed to be the cause in a majority of cases, certain food items and medications can also cause gastroenteritis.

Every year, worldwide 5–10 million people succumb to gastroenteritis,.2 It is a leading cause of death among infants and children under 5 years of age.3 Viral gastroenteritis, commonly referred to as ‘Stomach Flu’, is the second most common illness in USA, 1 causing millions of cases of diarrhea each year.

Although the statistics are disturbing, one has no cause for alarm if he or she is healthy. An otherwise healthy adult will recover from the illness by drinking fluids and easing up on the diet for a few days. But for infants, the elderly, and in people with low levels of immunity, gastroenteritis can be a life-threatening illness. 


Signs and Symptoms of gastroenteritis 

Symptoms of gastroenteritis depend upon the type of organism causing the infection.

The severity of the symptoms depends on the body’s resistance.

Some of the common symptoms of gastroenteritis are:

  • Nausea with or without vomiting
Usually, the symptoms begin suddenly; occur 1–3 days after a person acquires the infection, and last 1–2 days. Occasionally, the symptoms may persist for longer.

Viral gastroenteritis is characterized by watery diarrhea. If one notices blood in the stools, then he or she probably have bacterial diarrhea. In children, vomiting is more prominent than diarrhea. In adults, diarrhea predominates.


Causes of gastroentiritis

Most often, a person will develop gastroenteritis after contact with an infected person or due to ingestion of contaminated food (such as shellfish harvested from contaminated sources) or water. Unhygienic practices, like inadequate washing of hands after using the restroom, also aid the spread of the disease.

Gastroenteritis is caused by viruses and bacteria, and less often by parasites and protozoa. Sometimes, one may develop gastroenteritis if he or she consumes food items, which irritate the intestines.

Viral gastroenteritis

Viral gastroenteritis1is caused by four major categories of viruses:

  1. Rotavirus
  2. Norovirus
  3. Adenovirus
  4. Astrovirus

Rotavirus: This is the most common cause of severe debilitating diarrhea in young children, sometimes requiring hospitalization. Infected adults are usually unaffected, but can spread the illness.

Norovirus: Older children and adults are usually affected by noroviruses. This virus is responsible for epidemics and seasonal outbreaks of gastroenteritis.2 If a person experienced muscle ache, fatigue, and headache in addition to the usual symptoms of diarrhea and vomiting, it is more likely that he or she has norovirus gastroenteritis.

Adenovirus: This virus affects children under the age of 2 years. Symptoms of infection with adenoviruses take a longer time to appear.

Astrovirus: Infections with astroviruses are more common in the winter months and in young children.

Bacterial gastroenteritis

Bacterial gastroenteritis3is less common than viral gastroenteritis. Common bacteria that cause gastroenteritis are:

  1. Campylobacter and Salmonella spp
  2. Shigella spp
  3. Escherichia coli

Campylobacter and Salmonella spp.: These are the most common causes of bacterial diarrhea. The infection is generally acquired from undercooked eggs and dairy products. Also, if the pet dogs or cats have campylobacter infection, then a person acquire the infection from them.

Shigella spp: Infection with Shigella spp. tends to be more severe in children and the elderly.

Escherichia coli: Several variants of this bacteria cause gastroenteritis. The most common type of infection with E. coli occurs when a person consumes undercooked ground beef, unpasteurized milk and juice, and contaminated water.7 Person-to-person contact also occurs in settings such as daycare centers and nurseries. A variant of E. coli causes a watery diarrhea, commonly referred to as ‘travelers’ diarrhea’.5

Other bacteria such as Clostridium perfringens, Staphylococcus aureus and Bacillus cereus produce symptoms by releasing toxins into contaminated food.

Parasites and protozoa

Parasites and protozoa are less frequently responsible for gastroenteritis. One of these microorganisms can be picked up from the swimming pool or by drinking contaminated water. Some common parasites, which cause gastroenteritis are as follows:3

Giardia: Infection resulting from Giardia is more common in colder climates and spreads from person-to-person or through contaminated drinking water.

Cryptosporidium spp.: Infection with this parasite can be lethal in people with a weakened immune system.

Entamoeba spp.: Infection with Entamoeba histolytica, which is less common in USA, results in a bloody diarrhea.

Other causes of gastroenteritis include the following:
  • Consumption of drinking water contaminated with heavy metals such as arsenic, lead, and mercury.
  • Inability to tolerate the lactose in milk products (lactose intolerance).6
  • Side-effects of medications such as antacids, antibiotics, chemotherapy drugs and laxatives. 

Diagnosis and Tests of gastroenteritis

Gastroenteritis is generally diagnosed based on the symptoms, which are highly characteristic. A history of similar symptoms in the family and neighborhood aids in the diagnosis.

Some of the questions that a medical professional may ask the patient to determine the cause of the infection those are following: 

  • How long have you had the symptoms? Long lasting symptoms may be indicators of immune disorders or a chronic inflammation, rather than gastroenteritis.
  • Have you recently undertaken any travel?
  • Have you consumed stale food?
  • Have you introduced something new in your diet?
  • Have you been taking any medication?

A stool test may be required to diagnosis the specific bacteria or parasite causing the infection. A rapid stool test can also identify rotavirus infection. Currently, there are no other tests to identify infections caused by other viruses. In cases of severe dehydration, blood electrolytes levels may be monitored to restore hydration levels.

Complication of Gastroenteritis: Dehydration 

Dehydration (low water in the body) is the most serious and life-threatening complication of gastroenteritis. Prolonged vomiting and diarrhea result in the loss of fluids as well as electrolytes from the body, causing dehydration.1

If one is otherwise healthy, and are drinking enough fluids to replace the loss, then, he or she need not worry about dehydration. However, infants, older adults, and people with low immunity become dehydrated quickly. Monitor them carefully to catch the signs of dehydration early. Extreme dehydration can be fatal.

Signs of dehydration in adults:
  • Excessive thirst
  • Little or no urine
A child maybe dehydrated if he or she shows any of the following signs:
  • Does not wet a diaper in 6 h
  • Passes blood in stools
  • Has a sunken fontanel (soft area on the top of the baby’s head)
  • Is drowsy or unresponsive
  • Cries without tears

Severely dehydrated children and adults will require hospitalization, where fluids and electrolytes will be replaced intravenously (through a vein).   


Treatment of Gastroenteritis

Most cases of gastroenteritis are self-limiting, requiring no medication. Self-care at home may help relieve the symptoms and prevent dehydration.

Follow these steps at home to recover from a bout of gastroenteritis.

  • Drink plenty of fluids. Even if you are vomiting, drink as much water as you can tolerate, in small sips.
  • Get plenty of rest. The loss of fluids would have left the person weak and tired. Exertion will only contribute to the dehydration.
  • Go easy on food. Avoid dairy products, coffee and tea, alcohol, and oily food. When the person is able to keep things down, restrict him- or herself to easy-to-digest foods, like bananas, toast, crackers, and rice.
  • Avoid medications, unless prescribed by a medical professional. They may add to the stomach irritation, making the condition worse.
  • Use oral rehydration solutions (ORS) to keep the child hydrated.1 Water may not be absorbed well, and carbonated drinks, apple juice, and sports drinks are not suitable for children.
  • Continue breastfeeding your child even when he or she has a bout of gastroenteritis. It is very rare for a baby to have to stop breastfeeding.

Medication may be of help in certain situations. Gastroenteritis arising from parasitic infection is treated with antiparasitic drugs such as metronidazole and nitazoxanide. The patient may be advised to take antibiotics if he or she has bacterial infection. Probiotics (good bacteria) have recently gained popularity and have been known to reduce the severity of rotavirus diarrhea.2


Who is at Risk?

Gastroenteritis is a great equalizer; no one is immune from the disease. However, certain categories of people are at a greater risk of contracting the illness than others.

  • Children and workers in daycare centers and nurseries
  • Students living in dormitories
  • Military employees
  • Travelers

Prevention of gastroenteritis

Gastroenteritis is contagious and the best way to prevent infections from spreading is to maintain hygiene. Some steps you can take to avoid getting the infection are:

  • Wash the hands thoroughly, especially after a visit to the bathroom. Teach the children to wash their hands with soap and water.
  • Avoid sharing plates, glasses and towels.
  • If somebody, who has gastroenteritis enters other’s vicinity, try to maintain a distance.
  • Make sure that the day-care center you choose for your child maintains cleanliness. It should have a safe and sanitary diaper disposal mechanism.
  • While traveling, drink bottled water and avoid eating raw food and undercooked meat.
  • Get your child immunized with the vaccine against rotavirus. An FDA approved vaccine is available to protect infants against rotavirus gastroenteritis.1

Gastroenteritis is a manageable illness, requiring nothing more than self-care at home, in most cases. At the same time, it is also easily preventable. Following the basic principles of cleanliness and hygiene prevents the spread of the illness.


When to Seek Medical Care for gastroenteritis 

Generally, the symptoms arising from gastroenteritis range from mild–to-moderate. If the symptoms are severe and not improving with homecare, then the patient may require medical intervention. If the patient is an adult with any of the following condition, then, he or she has to visit a medical professional

  • Vomiting for more than 48 h.
  • Blood in the vomit
  • High fever
  • Abdomen starts swelling
  • Dehydration
Gastroenteritis can be a serious illness in children. Small children and infants can get dehydrated quickly. 
Consultation with a pediatrician is must if the child:
  • Has a high temperature
  • Is lethargic or irritable
  • Seems to be in pain
  • Seems dehydrated

Written by: Healthplus24 team
Date last updated: September 30, 2012

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