Warts are transmitted by touch, but do not appear immediately after contact with an infected person, but two to six months after the skin has been exposed to the virus. They are harmless and, in some cases, may disappear on their own. When they don't, they multiply and become extremely unsightly, and when they are located on the nails, for example, they can deform them.
Most papillomas are also caused by a virus (from the HPV family, more precisely the human papilloma virus), which is transmitted through human contact (touch). They often appear in adulthood and in very old people. Skin damage plays an important role, but so do a number of conditions such as diabetes, acromegaly, obesity and some thyroid conditions. There are also genetic papillomas (inherited from parents). Papillomas can sometimes be easily confused with other lesions such as various types of moles or a neurofibroma, which is why doctors do not recommend home treatments.