Diarrhea is loose, watery stools that typically occur several times a day. Prolonged, or chronic, diarrhea can be dangerous as it can lead to dehydration, or a lack of fluid within the body. Diarrhea is a common occurrence and the National Digestive Diseases Information Clearinghouse reports that the average adult will experience at least four cases of acute (meaning sudden onset) diarrhea a year. There are many different organisms, conditions and diseases that can cause diarrhea.
Viral Infections
Viral gastroenteritis is the swelling and irritation of the stomach and intestines caused by a virus. The resulting diarrhea and vomiting is often referred to as the "stomach flu," although it is not caused by an influenza virus. Viruses that commonly cause diarrhea include the rotavirus, norovirus and some strains of adenovirus. There is no specific treatment for viral gastroenteritis except to be sure the patient drinks enough fluids to replace what is lost.
Bacterial Infections
Irritation of the gastrointestinal system can also be caused by bacteria. Bacterial infections, including campylobacter, salmonella, shigella and escherichia coli (E. coli), are often passed through contaminated food or water. These types of infections, often referred to as food poisoning, can cause abdominal cramping or pain, bloody stools, nausea and loss of appetite in addition to the diarrhea. Treatment is usually not necessary as the infection will subside within a few days, according to the National Institutes of Health.
Parasites
Parasites, often ingested in contaminated water, can cause diarrhea. There are two types of intestinal parasites, according to the University of Maryland Medical Center: small multi-cellular worms and one-celled protozoa. The most common parasitic infections are caused by the protozoa Giardia lamblia and Cyptosporidium. To remove the parasites from the digestive tract, treatment with medications such as metronidazole or nitazoxanide is necessary.
Food Intolerance
The inability to digest components in certain foods, known as food intolerance, can also result in diarrhea. The most common food intolerance is to lactose, the sugar component of milk. Food intolerance is different from a food allergy, as it does not trigger an immune response in the body. Other common triggers of food intolerance include sulfites, monosodium glutamate (a flavor enhancer) and gluten (the protein found in wheat).
Intestinal Diseases
There are many diseases that affect the intestines causing chronic or persistent diarrhea. The most common intestinal diseases are inflammatory bowel disease, Crohn's disease and celiac disease. These diseases cause inflammation of the intestines,which triggers them to empty, frequently resulting in diarrhea.
Functional Bowel Disorder
Irritable bowel syndrome (IBS) is a functional bowel disorder that causes diarrhea, abdominal pain, bloating and constipation. Some people who suffer with IBS will alternate between experiencing constipation and diarrhea. Symptoms of IBS can often be controlled with diet and stress management, but there are also medications that can help.
