Take the Tummy Trouble Quiz Digestive Disease Myths Slideshow Pictures Heartburn? Foods to Eat, Foods to Avoid Slideshow

Medical Author:

Benjamin Wedro, MD, FACEP, FAAEM

Benjamin Wedro, MD, FACEP, FAAEM

Dr. Ben Wedro practices emergency medicine at Gundersen Clinic, a regional trauma center in La Crosse, Wisconsin. His background includes undergraduate and medical studies at the University of Alberta, a Family Practice internship at Queen's University in Kingston, Ontario and residency training in Emergency Medicine at the University of Oklahoma Health Sciences Center.

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Medical Editor:

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, Chief Medical Editor

Melissa Conrad Stöppler, MD, is a U.S. board-certified Anatomic Pathologist with subspecialty training in the fields of Experimental and Molecular Pathology. Dr. Stöppler's educational background includes a BA with Highest Distinction from the University of Virginia and an MD from the University of North Carolina. She completed residency training in Anatomic Pathology at Georgetown University followed by subspecialty fellowship training in molecular diagnostics and experimental pathology.

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Gastroenteritis Causes

Gastroenteritis has many causes. Viruses and bacteria are the most common.

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. The infection can spread from person to person because of improper handwashing following a bowel movement or handling a soiled diaper.

Gastroenteritis caused by viruses may last one to two days. However, some bacterial cases can continue for a longer period of time.

Viruses

Norovirus - Fifty to seventy percent of cases of gastroenteritis in adults are caused by the noroviruses (genus Norovirus, family Caliciviridae. This virus is highly contagious and spreads rapidly. Norovirus is the most common cause of gastroenteritis in the United States.

• Noroviruses can be transmitted and infect individuals by
  • contaminated food and liquids,
    
    
  • touching objects contaminated with norovirus and then placing the hands or fingers in the mouth,
    
    
  • direct contact with an infected individual (for example, exposure to norovirus when caring or sharing foods, drinks, eating utensils with an affected individual, and
    
    
  • exposure to infected individuals and objects in daycare centers and nursing homes.
    
    
• Norovirus is often in the news when cruise ship passengers contract the virus, which causes gastroenteritis.

Rotavirus - According to the CDC, "Rotavirus was also the leading cause of severe diarrhea in U.S. infants and young children before rotavirus vaccine was introduced for U.S. infants in 2006. Prior to that, almost all children in the United States were infected with rotavirus before their 5th birthday. Each year in the United States in the pre-vaccine period, rotavirus was responsible for more than 400,000 doctor visits; more than 200,000 emergency room visits; 55,000 to 70,000 hospitalizations; and 20 to 60 deaths in children younger than 5 years of age."

Other viruses that cause gastrointestinal symptoms include:

• Adenoviruses - This virus most commonly causes respiratory illness; however, other illnesses may be caused by adenoviruses such as gastroenteritis, bladder infections, and rash illnesses.
  
  
• Parvoviruses - The human bocavirus (HBoV), which can cause gastroenteritis belongs to the family Parvoviridae.
  
  
• Astroviruses - Astrovirus infection is the third most frequent cause of gastroenteritis in infants.

Bacteria

Bacteria may cause gastroenteritis directly by infecting the lining of the stomach and intestine. Some bacteria such as Staphylococcus aureus produce a toxin that is the cause of the symptoms. Staph is a common type of food poisoning.

Escherichia coli infection can cause significant complications. E. coli O157:H7 (one type of the bacteria) can cause complications in approximately 10% of affected individuals (for example, kidney failure in children [hemolytic-uremic syndrome or HUS), bloody diarrhea, and thrombotic thrombocytopenic purpura (TTP) in the elderly.

Salmonella, Shigella and Campylobacter

Salmonella, Shigella and Campylobacter are also common causes of illness.

• Salmonella is contracted by ingesting the bacteria in contaminated food or water, and by handling poultry or reptiles such as turtles that carry the germs.
  
  
• Campylobacter occurs by the consumption of raw or undercooked poultry meat and cross-contamination of other foods. Infants may contract the infection by contact with poultry packages in shopping carts. Campylobacter is also associated with unpasteurized milk or contaminated water. The infection can be spread to humans by contact with infected stool of an ill pet (for example, cats or dogs). It is generally not passed from human to human.
  
  
• Shigella bacteria generally spreads from an infected person to another person. Shigella are in diarrheal stools of infected individuals while they are ill, and for up to one to two weeks after contracting the infection. Shigella infection also may be contracted from eating contaminated food, drinking contaminated water, or swimming or playing in contaminated water (for example, wading pools, shallow play fountains). Shigella can also be spread among men who have sex with men.

Clostridium difficile

Clostridium difficile (C difficile) bacteria may overgrow in the large intestine after a person has been on antibiotics for an infection. The most common antibiotics that pose a potential risk factor for C difficile include

• clindamycin (for example, Cleocin),
  
  
• fluoroquinolones (for example, levofloxacin [Levaquin'], ciprofloxacin [Cipro, Cirpo XR, Proquin XR]),
  
  
• penicillins, and
  
  
• cephalosporins.

Other risk factors for C difficile infection are hospitalization, individuals 65 years of age or greater, and existing chronic medical conditions.

Parasites and Protozoans

These tiny organisms are less frequently responsible for intestinal irritation. A person may become infected by one of these by drinking contaminated water. Swimming pools are common places to come in contact with these parasites. Common parasites include

• Giardia is the most frequent cause of waterborne diarrhea, causing giardiasis. Often, people become infected after swallowing water that has been contaminated by animal feces (poop). This may occur by drinking infected water from river or lakes but giardia may also be found in swimming pools, wells and cisterns.
  
  
• Cryptosporidium (Crypto) is a parasite that lives in the intestine of affected individuals or animals. The infected individual or animal sheds the Cryptosporidium parasite in the stool. Crypto may also be found in food, water, soil, or contaminated surfaces (swallowing contaminated recreational water, beverages, uncooked food, unwashed fruits and vegetables, touching contaminated surfaces such as bathroom fixtures, toys, diaper pails, changing tables, changing diapers, caring for an infected individual or handling an infected cow or calf). Those at risk for serious disease are individuals with weakened immune systems.

Other Common Causes of Gastroenteritis

Gastroenteritis that is not contagious to others can be caused by chemical toxins, most often found in seafood, food allergies, heavy metals, antibiotics, and other medications.