Diarrhea (cont.)

The symptoms that are associated with diarrhea depend on the cause and type of diarrhea.

• If there is a large secretory component to the diarrhea the bowel movements are frequent and watery. Pain is not common, and there are no signs of inflammation.
• Similarly, an osmotic diarrhea is watery, but it's main characteristic is that once ingestion of food stops (which would include the offending dietary food or substance that is not digested or absorbed) the diarrhea stops.
• Motility related diarrhea is more likely to be associated with cramping abdominal pain.
• Inflammatory diarrhea often is associated with crampy abdominal pain as well as signs of inflammation, for example, fever and abdominal tenderness. It also may be associated with intestinal bleeding, either with visible blood in the stool or invisible blood that only is detected by testing the stool for blood.
• Although one might expect the diarrhea of collagenous colitis to be painless (since diarrhea is believed to be due to poor absorption of fluid and electrolytes), in fact, it is frequently associated with abdominal pain, suggesting that there is more to collagenous colitis than a failure to absorb fluid and electrolytes.

The most common cause of acute diarrhea is infection--viral, bacterial, and parasitic. Bacteria also can cause acute food poisoning. A third important cause of acute diarrhea is starting a new medication.

Viral gastroenteritis (viral infection of the stomach and the small intestine) is the most common cause of acute diarrhea worldwide. Symptoms of viral gastroenteritis (nausea, vomiting, abdominal cramps, and diarrhea) typically last only 48-72 hrs. Unlike bacterial enterocolitis (bacterial infection of the small intestine and colon), patients with viral gastroenteritis usually do not have blood or pus in their stools and have little if any fever.

Viral gastroenteritis can occur in a sporadic form (in a single individual) or in an epidemic form (among groups of individuals). Sporadic diarrhea probably is caused by several different viruses and is believed to be spread by person-to-person contact. The most common cause of epidemic diarrhea (for example, on cruise ships) is infection with a family of viruses known as caliciviruses of which the genus norovirus is the most common (for example, "Norwalk agent"). The caliciviruses are transmitted by food that is contaminated by sick food-handlers or by person-to-person contact.

Source: MedicineNet.com
http://www.medicinenet.com/diarrhea/article.htm