Warts are caused by viruses and can cause infections. There are several different types of wart viruses. Warts thrive in warm, damp environments. The virus are easily spread in places like swimming pools, gyms and through direct contact. Some people only get one wart, while others may have several. It is not unusual to have up to 10–20 warts. It is often easier to get rid of new warts than those that have been there for many years.