Anal ulcers may be caused by local skin ulceration due to lack of attention to anal hygiene, such as not wiping clean feces after a bowel movement, resulting in bacterial infection of the skin. It is recommended to pay more attention when having sex because the virus is caused by impure sex and indirect infection. It may also be caused by anal fissures, because the fissured part of the anus does not heal for a long time, and the feces will stimulate the wound when defecating causing it to become infected or form chronic ulcers, and may also be accompanied by chronic eczema.