What is a wart?
A wart is a benign growth that protrudes from a surface. It can be classified as being genital or non-genital. Skin warts are non-genital warts that protrude from the surface of the skin. It is also known as common warts and it is caused by the human papilloma virus (HPV) that is often transmitted by touch. However, skin warts are not associated with sexual contact as is the case with genital warts.
The exact prevalence of warts is unknown but it is estimated to affect as much as 12% of the global population, with a higher incidence of as much as 20% among children. People with weakened immune systems also tend to develop warts more frequently. Men and women are affected equally by non-genital warts and is unusual in early childhood but the incidence peaks between the ages of 12 and 16 years.
Causes of Warts
Skin warts are caused by a virus known as human papilloma virus (HPV). There are over 100 sub-types of this virus but only a few infect humans to cause warts on the skin. The virus enters the skin cells and replicated like all viruses do but does not extend beyond the skin. It cannot enter the body and disseminate through the bloodstream or lymphatic system. The type of HPV that causes skin warts are largely harmless unlike the type that can cause cancer of the cervix (cervical cancer) in women.
How are warts spread?
Unlike the countless myths that surround the spread of warts, the virus is transmitted from direct contact with the virus. It can be spread from making direct (skin-to-skin) contact with a person who has warts but can also be spread indirectly through objects they have touched (fomites). If the virus is present on these objects and another person then touches it, the virus can then be passed on.
Due to the ease by which virus travels, warts may be developed after making contact with a host of different objects especially in public places like on fitness equipment at a gym. However, in order for the virus to cause warts there has to be a break in the skin but even the tiniest tear of the skin may be sufficient for the virus to enter and replicate. Autoinnoculation is where a person spread the virus from a wart in one area of the body to another, usually due to scratching.
Signs and Symptoms
Warts are at times mistaken for other skin lesions like skin tag (acrochordon) and moles. A wart is not a big black protrusion from the skin surface as is sometimes thought. It is relatively small protrusions from the skin surface that are often skin-colored or may appear white, pink or a light brown color. It may have black spots at the tip which is due to a thrombosed (clotted) blood vessel but this is not always present. Warts can also be felt as roughness of the skin or little bumps.
Types and Pictures
There are different types of warts categorized by their location and appearance.
- Common warts are usually found on the limbs, especially around joints, like the fingers, toes and knees.
- Periungual warts are found around the nails can can affect normal nail growth.
- Filiform warts are on a long stalk and protrude significantly above the surface compared to flat warts.
- Plane warts usually occur in large numbers and often on areas of the skin that are shaved.
- Plantar warts are found on the sole of the foot an occur as a solitary wart or a few may be present at the same time. These warts are also known as verrucas and grow inward.
- Mosaic warts are also found on the sole of the foot but tend to occur in clusters within a small area of the skin.
Picture of common warts
Picture of filiform wart
Picture of plantar wart
Treatment of Warts
Up to 65% of warts are regress on their own within 2 years. Therefore treatment may not always be necessary but it is advisable to prevent autoinnoculation at other sites by treating existing warts.
More often than not the choice of treatment depends on the individual as warts are more often than not a cosmetic issue. However, there are instances where warts can pose a problem beyond the aesthetic aspect. Plantar warts for example can be painful and impede walking. There are several treatment options and the least invasive and least expensive options should first be considered.
- Salicylic acid is a very effective first line of treatment which gradually removes layers of dead skin cells. It may be combined with cryotherapy.
- Chloroacetic acids are stronger acids that may be used if salicylic acid fails to yield the desire results. The outer layer of skin may need to be removed before these acids are applied.
- Cryotherapy (freezing) is also effective to either stimulate the immune system to act in the area or to destroy the infected skin.
- Laser treatment may be used to burn the wart, damaging its blood vessels and leading to death of the tissue which can then fall off in time.
- Curettage and cautery is where the wart is cut away and the area is sealed with heat. It causes scarring in the area and there is a risk of recurrence.
Prevention of Warts
It is difficult to avoid the human papilloma virus that causes warts altogether. In the course of modern life, most people touch objects that others come into contact with and the virus may be on any of these objects. Furthermore social gestures like shaking hands makes it difficult to avoid skin-to-skin contact altogether. However, simply ensuring that all open wounds on the skin is properly treated and covered can reduce the chance of HPV infecting the skin.
Never interfere with warts, pick at it or try to rub it down with pumice boards or any other abrasive. This increases the chance of spreading the virus elsewhere and causing more warts at other locations. It is not always possible to avoid contact with warts entirely but it is important to wash the hands thoroughly with an antiseptic soap or handwash after touching the warts.