Diarrhoea

Diarrhea is a common symptom that can range in severity from an acute, self-limited annoyance to a severe, life-threatening illness. The frequency and consistency of bowel move-ments vary within and between individuals. Some individuals may normally defecate as many as three times a day, while others only two to three times per week. Diarrhea is defined as increased volume, fluidity, or frequency of fecal discharges compared with the patient’s normal stools. Clinical features vary greatly depending on the cause, duration, and severity of the diarrhea, on the area of bowel affected, and on the patient’s general health.
While there are many causes of diarrhea, it is most often due to an enteritis (inflammation of the small intestine) of infectious or noninfectious etiology. In the U.S., most cases of infectious diarrhea are of viral and bacterial origin. Most infectious diarrheas are acquired by fecal-oral transmission via contaminated food or water. Improperly cooked meats may also be the source of infection.
Diarrhea results from an imbalance in the absorption and secretion properties of the intestinal tract; if absorption decreases or secretion increases beyond normal, diarrhea results.
Diarrhea may be acute or chronic. Acute diarrhea is the abrupt onset of frequent, watery, loose stools. It may be accompanied by flatulence, malaise and abdominal pain. Some clinicians consider acute diarrhea to be the passage of three or more loose stools in a 24-hour period, continuing for less than two weeks. Usually, acute diarrheal episodes subside within 72 hours of onset. In the U.S., common diarrhea-producing pathogens are Shigella, Salmonella, Campylobacter, Staphylococcus, Bacillus cereus, Norwalk viruses and rotaviruses.
Toxigenic Escherichia coli and S. aureus cause diarrhea through an enterotoxin, while Shigella, Salmonella, Campylobacter and invasive E. coli directly invade the mucosal epithelial cells. Toxin-producing pathogens usually cause a watery,...