Campylobacter is the leading cause of bacterial diarrhea worldwide, responsible for more cases (2 million or more) of bacterial diarrhea in the United States than Shigella and Salmonella combined.
Shigella accounts for 10 to 20 percent of all cases of diarrhea worldwide, and in any given year infects over 140 million persons and kills 600,000, mostly children and the elderly.
Shigella are very resistant to the acid produced by the stomach, and this allows them to easily pass through the gastrointestinal tract and infect the colon (large intestine).
A variety of bacteria cause food poisoning, including Salmonella, Staphylococcus aureus, Campylobacter jejuni, Escherichia coli, Shigella, and Clostridium botulinum.
The symptoms of food poisoning by Shigella organisms may resemble meningitis and a differential diagnosis must be made by isolating the causative bacteria.
Cholera and Shigella remain two diseases of great concern in developing countries, and research to develop long-term vaccines against them is underway.
Four different groups of Shigella can affect humans; of these, S. dysenteriae generally produces the most severe attacks, and S. sonnei the mildest.
Shigella is only one of several organisms that can cause dysentery, but the term bacillary dysentery is usually another name for shigellosis.
Bloody diarrhea, sometimes called dysentery, is produced by EHEC, EIEC, some types of Salmonella, some types of Shigella, and Yersinia.
Shigella also produce a number of toxins (Shiga toxin and others) that increase the amount of fluid secretion by the intestinal tract.