Types and Causes of Warts

A wart (also known as verruca) is generally a small, rough tumor, typically on hands and feet but often other locations, that can resemble a cauliflower or a solid blister. Warts are common, and are caused by a viral infection, specifically by the human papillomavirus (HPV) and are contagious when in contact with the skin of an infected person. It is also possible to get warts from using towels or other objects used by an infected person. They typically disappear after a few months but can last for years and can recur.

Warts are caused by a virus called human papilloma virus or HPV. There are approximately 100 strains of human papilloma viruses. Type 1, 2, and 3 causes most of the common warts. Type 1 is associated with deep plantar (sole of the feet) and palmar warts (palm of the hand). Type 2 causes common warts, filiform warts, plantar warts, mosaic plantar warts. Type 3 causes plane warts, or commonly known as flat warts. Anogenital warts are caused by types 6, 11, 16, 18, 30, 31, 33, 34, 35, 39, 40 and others. HPV types 6 and 11 cause about 90% of genital warts cases. HPV types 16 and 18 currently cause about 70% of cervical cancer cases, and also cause some vulvar, vaginal, penile and anal cancers. Gardasil, a vaccine for HPV is designed to prevent infection with HPV types 16, 18, 6, and 11; it is claimed to prevent infections to other strains of anogenital warts through cross protection against other types of HPVs. HPV is associated with oral cancer, laryngeal cancers, tracheal and lung cancers.

Types of wart

A range of different types of wart has been identified, varying in shape and site affected, as well as the type of human papillomavirus involved. These include

• Common wart (Verruca vulgaris), a raised wart with roughened surface, most common on hands and knees;
• Flat wart (Verruca plana), a small, smooth flattened wart, flesh coloured, which can occur in large numbers; most common on the face, neck, hands, wrists and knees;
• Filiform or digitate wart, a thread- or finger-like wart, most common on the face, especially near the eyelids and lips;
• Plantar wart (verruca, Verruca pedis), a hard sometimes painful lump, often with multiple black specks in the center; usually only found on pressure points on the soles of the feet;
• Mosaic wart, a group of tightly clustered plantar-type warts, commonly on the hands or soles of the feet;
• Genital wart (venereal wart, Condyloma acuminatum, Verruca acuminata), a wart that occurs on the genitalia.