The severe tissue destruction caused by Shigella spp. results in an impaired adsorption of water, nutrients, and solutes, which might cause the watery diarrhea as well as the blood and mucus in stools characteristic of shigellosis. A disturbance of electrolyte homeostasis and changes in membrane transport processes, such as uncontrolled ion and fluid secretion, are typical of diarrheal diseases (147). However, the exact mechanism underlying the onset of diarrhea during shigellosis is still poorly defined. Notably, Shigella enterotoxin 1 (ShET1) and ShET2, which are produced by several Shigella strains, were found to induce fluid secretion into the intestine, thus accounting for the watery phase of diarrhea (70, 183). Moreover, Shiga toxin, which is produced only by Shigella dysenteriae serotype 1, is cytotoxic for a variety of cell types and is responsible for the development of vascular lesions in the colon, the kidney, and the central nervous system (37). Due to the high toxicity of Shiga toxin, infections with S. dysenteriae serotype 1 are frequently associated with life-threatening complications (37, 199).