Why do common warts occur?

The main causes of common warts include: 1. Infection factors: Common warts are primarily caused by infection of the skin and mucous membranes by human papillomavirus (HPV). When the skin or mucous membrane is damaged, HPV enters the epithelial cells through the wound and replicates within them, leading to abnormal differentiation and proliferation of epithelial cells, thus forming common warts. 2. Weakened immune system: Long-term irregular作息 (作息 should be translated as "作息" here, but since it's not translatable directly, consider replacing with "lifestyle habits"), excessive fatigue, or underlying medical conditions such as diabetes and chronic renal insufficiency may lead to a weakened immune system, reducing the body's ability to resist HPV infection and increasing the risk of developing common warts. 3. Skin injuries: When the skin sustains trauma, friction, or scratches, the damaged epidermal cells provide an entry point for HPV infection, making it easier to develop common warts. 4. Unhealthy lifestyle habits: Habits such as long-term sleep deprivation and irregular eating patterns may reduce the body's immunity, thereby increasing the risk of HPV infection. 5. Genetic factors: Some individuals may be naturally susceptible to HPV infection due to genetic predisposition, making them more prone to develop common warts.