|Demodex is a genus of tiny parasitic mites that live in or near hair follicles of mammals. About 65 species of Demodex are known; they are among the smallest of arthropods.|
Gross, yes, but even grosser for people with rosacea: They can have up to 10 times the number of mites in their skin. Because Demodex mites don't have anuses, they don't poop, and their feces just builds up in their bodies until they die, usually inside our pores. For people with rosacea, when all those critters die, it releases a lot of fecal bacteria all at once, causing an immune reaction and inflammation. You can read an abstract of the original article at the Journal of Medical Microbiology.