Human papillomaviruses cause warts on fingers through an infection in the top layer of the skin that leads to a rapid growth of cells, as WebMD explains. The infection usually invades the skin through a small scratch or scrape or through an opening created by nail biting.
People who have warts on their fingers came into contact with an individual, either directly or indirectly, who has warts, according to WebMD. Contact occurs through activities such as handshaking or using a towel that was used previously by someone with warts. While doctors are not sure why some people are more susceptible to warts than others as of 2015, they believe the cause is related to the effectiveness of their immune systems.
People who have contracted warts in the past can help prevent future outbreaks by washing their hands regularly, cleaning shared gym equipment and by wearing shoes when in common shower areas, as WebMD advises. People should also avoid biting their fingernails or tugging on hangnails if they are susceptible to developing warts on their fingers. People should treat warts immediately with over-the-counter medications or with home remedies such as putting clear nail polish or tape over warts to prevent them from spreading. Doctors remove warts by freezing or burning them off, and they may prescribe medications that boost the immune system.