Figure 8.

Shortening of villi associated with viral infections. Viral infections including astrovirus and norovirus cause villus blunting or shortening of the villi. There is a decrease in the number of cells making up the villi, reducing the overall absorptive surface. Intestinal epithelial cells are generated from stem cells within the crypts and move toward the villus tip, where they are ultimately shed. Blunting can be caused by reduced cell proliferation, although in the case of norovirus it is associated with an apical villus infection, resulting in increased cell death. Villus blunting is also the cause of diarrhea associated with Celiac disease, which is autoimmune rather than pathogen caused.