Warts are caused by different strains of the human papilloma virus (HPV). The virus is present in the skin cells of a wart.
Over 100 different types (strains) of HPV have been identified. Different strains of HPV are responsible for causing different types of warts.
Spreading the virus
HPV is passed on through close skin-to-skin contact. It can also be passed on by indirect contact, for example, from contaminated objects, such as towels and shoes. Warts are thought to be contagious for as long as they are present on your body.
HPV is more likely to spread if the skin is wet, soft or has been in contact with a rough surface.
Warts can also be spread to other parts of your own body. For example, you can spread the virus if you:
- scratch, knock or bite a wart
- bite your nails or suck your fingers (if they have warts on them)
- shave your face or legs
This can cause the wart to break up and bleed, making it easier for the virus to spread. People with scratches or cuts on the soles of their feet are particularly vulnerable.
Warts can also be spread through contact with contaminated surfaces. Examples of possible contaminated surfaces include:
- the areas surrounding swimming pools
- communal washing areas
