Gastroenteritis is a condition that causes irritation and inflammation of the stomach and intestines (the gastrointestinal tract). An infection may be caused by bacteria or parasites in spoiled food or unclean water. Some foods may irritate your stomach and cause gastroenteritis. Lactose intolerance to dairy products is one example.
Many people who experience the vomiting and diarrhea that develop from these types of infections or irritations think they have "food poisoning," which they may, or call it "stomach flu," although influenza has nothing to do with it.
Travelers to foreign countries may experience "traveler's diarrhea" from contaminated food and unclean water.
- The severity of infectious gastroenteritis depends on your immune system’s ability to resist the infection. Electrolytes (these include essential elements of sodium and potassium) may be lost as you vomit and experience diarrhea.
- Most people recover easily from a short bout with vomiting and diarrhea by drinking fluids and easing back into a normal diet. But for others, such as babies and the elderly, loss of bodily fluid with gastroenteritis can cause dehydration, which is a life-threatening illness unless the condition is treated and fluids restored.
Gastroenteritis has many causes. Viruses and bacteria are the most common.
The infectious agents can come from outside your body or internally from some abnormal condition. For example, both normal and disease-causing intestinal bacteria may grow when antacids or other medication alter the stomach acidity.
Viruses and bacteria are very contagious and can spread through contaminated food or water. In up to 50% of diarrheal outbreaks, no specific agent is found. Improper handwashing following a bowel movement or handling a diaper can spread the disease from person to person.
Gastroenteritis caused by viruses may last 1-2 days. On the other hand, bacterial cases can last a week or more.
Bacteria: These are the most common bacterial causes:
- Traveler’s diarrhea, food poisoning, dysentery, colitis, or uremic syndrome
- Typhoid fever; handling poultry or reptiles such as turtles that carry the germs
Campylobacter - Undercooked meat, unpasteurized milk
Shigella - Dysentery
Viruses: Viral outbreaks (30-40% of cases in children) can spread rapidly through close contact among children in day care and schools. Poor handwashing habits can spread viruses. Common viral causes include the following:
Norovirus (formerly called Norwalk-like virus or NLV) and Norwalk virus
- Norovirus was attributed to 9 out of the 21 outbreaks of acute gastroenteritis on cruise ships reported to the CDC’s Vessel Sanitation Program from January 1, 2002, to December 2, 2002.
- Noroviruses cause about 23 million cases of acute gastroenteritis each year and are the leading cause of outbreaks.
Parasites and protozoans: These tiny organisms are less frequently responsible for intestinal irritation. You may pick up one of these by drinking contaminated water. Swimming pools are common places to come in contact with these parasites. Common parasites include these:
- Giardia - The most frequent cause of waterborne diarrhea causing giardiasis
- Cryptosporidium - Affects mostly people with weakened immune systems, causes watery diarrhea
Other common causes: Chemical toxins most often found in seafood, food allergies, heavy metals, antibiotics, and other medications also may be responsible for bouts of gastroenteritis that are not infectious to others.
- Nonsteroidal anti-inflammatory medicines (such as Motrin or Advil)
- Steroids - Excessive use or a sudden change in frequency or dosage
- Inability to tolerate the sugar lactose in milk and milk products such as cheese and ice cream
- Exposure to heavy metals sometimes present in drinking water